Researcher Profile and Settings

Affiliation

• Faculty of Veterinary Medicine　Veterinary Medicine　Disease Control

Job Title

• Associate Professor

Research funding number

• 80615732

J-Global ID

• 201301073815171932

Research Areas

• Life sciences / Veterinary medicine

Educational Organization

•  Bachelor's degree program　School of Veterinary Medicine
•  Doctoral (PhD) degree program　Graduate School of Infectious Diseases

Research Activities

Published Papers

• Development of a dual immunochromatographic test strip to detect E2 and Erns antibodies against classical swine fever

  Loc Tan Huynh, Eun-Ju Sohn, Youngmin Park, Juhun Kim, Tomohiko Shimoda, Takahiro Hiono, Norikazu Isoda, Sung-Hee Hong, Ha-Na Lee, Yoshihiro Sakoda

  Frontiers in Microbiology 15 2024/04/11 

  Background It is essential to consider a practical antibody test to successfully implement marker vaccines and validate vaccination efficacy against classical swine fever virus (CSFV). The test should include a serological antibody assay, combined with a tool for differentiating infected from vaccinated animals (DIVA). The immunochromatographic test strip (ICS) has been exclusively designed for detecting CSFV E2 antibodies while lacking in detecting E^rns antibodies, which can be employed and satisfy DIVA strategy. This study developed a novel ICS for detecting CSFV E2/E^rns dual-antibody. The effectiveness of ICS in evaluating the DIVA capability of two novel chimeric pestivirus vaccine candidates was assessed. Methods Recombinant E2 or E^rns protein was transiently expressed in the plant benthamiana using Agrobacterium tumefaciens. ICS was subsequently assembled, and goat anti-rabbit IgG and recombinant CSFV E2 or E^rns protein were plated onto the nitrocellulose membrane as control and test lines, respectively. The sensitivity and specificity of ICS were evaluated using sera with different neutralizing antibody titers or positive for antibodies against CSFV and other pestiviruses. The coincidence rates for detecting E2 and E^rns antibodies between ICS and commercial enzyme-linked immunosorbent assay (ELISA) kits were also computed. ICS performance for DIVA capability was evaluated using sera from pigs vaccinated with conventional vaccine or chimeric vaccine candidates. Results E2 and E^rns proteins were successfully expressed in N. benthamiana-produced recombinant proteins. ICS demonstrated high sensitivity in identifying CSFV E2 and E^rns antibodies, even at the low neutralizing antibody titers. No cross-reactivity with antibodies from other pestiviruses was confirmed using ICS. There were high agreement rates of 93.0 and 96.5% between ICS and two commercial ELISA kits for E2 antibody testing. ICS also achieved strong coincidence rates of 92.9 and 89.3% with two ELISA kits for E^rns antibody detection. ICS confirmed the absence of CSFV E^rns-specific antibodies in sera from pigs vaccinated with chimeric vaccine candidates. Conclusion E2 and E^rns proteins derived from the plant showed great potential and can be used to engineer a CSFV E2/E^rns dual-antibody ICS. The ICS was also highly sensitive and specific for detecting CSFV E2 and E^rns antibodies. Significantly, ICS can fulfill the DIVA concept by incorporating chimeric vaccine candidates.
• Continuous Introduction of H5 High Pathogenicity Avian Influenza Viruses in Hokkaido, Japan: Characterization of Viruses Isolated in Winter 2022–2023 and Early Winter 2023–2024

  Lim Yik Hew, Norikazu Isoda, Fumihito Takaya, Kohei Ogasawara, Daiki Kobayashi, Loc Tan Huynh, Tatsuru Morita, Rio Harada, Nikolay Gennadievich Zinyakov, Dmitriy Borisovich Andreychuk, Ilya Alexandrovich Chvala, Viktor Nikolaevich Irza, Yukiko Watanabe, Hiroko Fujita, Keisuke Saito, Takahiro Hiono, Yoshihiro Sakoda

  Transboundary and Emerging Diseases 2024 1 - 18 1865-1674 2024/03/14 

  High pathogenicity avian influenza (HPAI) has impacted poultry and wild birds globally. The number of H5 HPAI virus (HPAIV) infection cases in wild birds in Hokkaido (Northern Japan) was high in the last two seasons, contributing to virus spillover to resident birds and poultry. Therefore, H5 HPAIVs in birds and mammals in Hokkaido in winter 2022–2023 and 2023–2024 were monitored and viruses were phylogenetically, antigenically, and pathogenetically characterized. Thirty HPAIV isolates were subtyped and pathotyped by sequencing the hemagglutinin (HA) gene of viruses. Phylogenetic analysis of the HA gene revealed that all isolated HPAIVs were categorized into clade 2.3.4.4b and divided into three groups (G2b, G2c, and G2d). Most isolates belonging to subgroup G2d clustered with isolates in winter 2021–2022 in Hokkaido. The other isolates were categorized into two subgroups, G2b and G2c, mainly composed of isolates in Honshu Island in winter 2021–2022 and 2022–2023, respectively. Two H5 HPAIVs isolated in Eastern Russia in spring and autumn 2022 were genetically close to most Hokkaido isolates (G2d), and a virus isolated in Hokkaido in November 2023 was also grouped in subgroup G2d. Further analysis of all eight gene segments identified six types of gene constellations. Cross-hemagglutination inhibition test indicated that the antigenicity of H5 HPAIVs isolated in the last several seasons was similar within them but slightly different from that in the 2010s. Three chicken breeds were intranasally challenged with four representative isolates to assess their pathogenicity. All chickens except one broiler chicken were dead until 5-day postchallenge with different pathogenicity of these viruses. The pathogenicity of one HPAIV strain was significantly lower in broiler chickens than in layer chickens. The mixture of multiple characteristics of HPAIVs in Hokkaido was confirmed by bird migration routes. Thus, many HPAIVs can be brought and scattered anywhere on Earth.
• Editorial: Epidemiology of the transboundary swine diseases in Asia & Pacific

  Satoshi Ito, Jaime Bosch, Norikazu Isoda, Lam Thanh Nguyen, Marta Martinez Aviles

  Frontiers in Veterinary Science 11 2024/02/20
• Establishment of a superinfection exclusion method for pestivirus titration using a recombinant reporter pestiviruses

  Yume MIMURA, Takahiro HIONO, Loc Tan HUYNH, Saho OGINO, Maya KOBAYASHI, Norikazu ISODA, Yoshihiro SAKODA

  Journal of Veterinary Medical Science 0916-7250 2024
• Exploring Appropriate Strategies for Vaccination against Classical Swine Fever under a Dynamic Change in Antibody Titer in Sows after Starting Vaccination in a Japanese Farm Setting

  Makoto Ukita, Keisuke Kuwata, Eiji Tanaka, Ryota Matsuyama, Norikazu Isoda, Yoshihiro Sakoda, Takehisa Yamamoto, Kohei Makita

  Transboundary and Emerging Diseases 2023 1 - 15 1865-1674 2023/11/30 

  After 26 years of absence in Japan, a classical swine fever (CSF) outbreak occurred at a domestic pig farm in 2018. Vaccination against the CSF virus with a live attenuated vaccine at pig farms was restarted in October 2019, which was 13 years after the 2006 ban on vaccination. An individual-based simulation model for CSF antibody dynamics was developed to determine an effective CSF vaccination strategy for pig populations. In creating a simulated pig herd, the optimal vaccination age of piglets and the effect of vaccinating piglets twice were evaluated. Additionally, the herd immunity was monitored every 6 months for 4 years after the start of vaccination, and the effects of intensive sow replacement policies were assessed. The simulation results indicated that the vaccination age should be delayed relative to the age used before the 2006 ban on vaccination and shifted earlier, from 8 weeks to 6 weeks, as time elapses. The simulations indicated a tradeoff in protection between the weaning period (i.e., maternally derived antibodies) and the fattening period (i.e., by vaccine-induced antibodies). Mixing sows with high and low antibody titers, particularly sows that received the first vaccination and those born after the start of vaccination, resulted in a high variation in antibody titer among pigs on the farm. This study also clarified the positive effect of intensive sow replacement strategies on shortening the period in which sows show diverse titers. Differences in sow replacement rates among farms and/or the time lag in starting vaccination in different prefectures result in heterogeneity in herd immunity in Japan; thus, herd immunity status should be examined at every farm using this simulation model.
• Detection of H5N1 High Pathogenicity Avian Influenza Viruses in Four Raptors and Two Geese in Japan in the Fall of 2022.

  Kei Nabeshima, Yoshihiro Takadate, Kosuke Soda, Takahiro Hiono, Norikazu Isoda, Yoshihiro Sakoda, Junki Mine, Kohtaro Miyazawa, Manabu Onuma, Yuko Uchida

  Viruses 15 (9) 2023/09/01 

  In the fall of 2022, high pathogenicity avian influenza viruses (HPAIVs) were detected from raptors and geese in Japan, a month earlier than in past years, indicating a shift in detection patterns. In this study, we conducted a phylogenetic analysis on H5N1 HPAIVs detected from six wild birds during the 2022/2023 season to determine their genetic origins. Our findings revealed that these HPAIVs belong to the G2 group within clade 2.3.4.4b, with all isolates classified into three subgroups: G2b, G2d, and G2c. The genetic background of the G2b virus (a peregrine falcon-derived strain) and G2d viruses (two raptors and two geese-derived strains) were the same as those detected in Japan in the 2021/2022 season. Since no HPAI cases were reported in Japan during the summer of 2022, it is probable that migratory birds reintroduced the G2b and G2d viruses. Conversely, the G2c virus (a raptor-derived strain) was first recognized in Japan in the fall of 2022. This strain might share a common ancestor with HPAIVs from Asia and West Siberia observed in the 2021/2022 season. The early migration of waterfowl to Japan in the fall of 2022 could have facilitated the early invasion of HPAIVs.
• Generation and Efficacy of Two Chimeric Viruses Derived from GPE− Vaccine Strain as Classical Swine Fever Vaccine Candidates

  Loc Tan Huynh, Norikazu Isoda, Lim Yik Hew, Saho Ogino, Yume Mimura, Maya Kobayashi, Taksoo Kim, Tatsuya Nishi, Katsuhiko Fukai, Takahiro Hiono, Yoshihiro Sakoda

  Viruses 15 (7) 1587 - 1587 2023/07/20 

  A previous study proved that vGPE− mainly maintains the properties of classical swine fever (CSF) virus, which is comparable to the GPE− vaccine seed and is a potentially valuable backbone for developing a CSF marker vaccine. Chimeric viruses were constructed based on an infectious cDNA clone derived from the live attenuated GPE− vaccine strain as novel CSF vaccine candidates that potentially meet the concept of differentiating infected from vaccinated animals (DIVA) by substituting the glycoprotein Erns of the GPE− vaccine strain with the corresponding region of non-CSF pestiviruses, either pronghorn antelope pestivirus (PAPeV) or Phocoena pestivirus (PhoPeV). High viral growth and genetic stability after serial passages of the chimeric viruses, namely vGPE−/PAPeV Erns and vGPE−/PhoPeV Erns, were confirmed in vitro. In vivo investigation revealed that two chimeric viruses had comparable immunogenicity and safety profiles to the vGPE− vaccine strain. Vaccination at a dose of 104.0 TCID50 with either vGPE−/PAPeV Erns or vGPE−/PhoPeV Erns conferred complete protection for pigs against the CSF virus challenge in the early stage of immunization. In conclusion, the characteristics of vGPE−/PAPeV Erns and vGPE−/PhoPeV Erns affirmed their properties, as the vGPE− vaccine strain, positioning them as ideal candidates for future development of a CSF marker vaccine.
• Genetic, Antigenic, and Pathobiological Characterization of H9 and H6 Low Pathogenicity Avian Influenza Viruses Isolated in Vietnam from 2014 to 2018.

  Kien Trung Le, Lam Thanh Nguyen, Loc Tan Huynh, Duc-Huy Chu, Long Van Nguyen, Tien Ngoc Nguyen, Tien Ngoc Tien, Keita Matsuno, Masatoshi Okamatsu, Takahiro Hiono, Norikazu Isoda, Yoshihiro Sakoda

  Microorganisms 11 (2) 2023/01/18 

  The H9 and H6 subtypes of low pathogenicity avian influenza viruses (LPAIVs) cause substantial economic losses in poultry worldwide, including Vietnam. Herein, we characterized Vietnamese H9 and H6 LPAIVs to facilitate the control of avian influenza. The space-time representative viruses of each subtype were selected based on active surveillance from 2014 to 2018 in Vietnam. Phylogenetic analysis using hemagglutinin genes revealed that 54 H9 and 48 H6 Vietnamese LPAIVs were classified into the sublineages Y280/BJ94 and Group II, respectively. Gene constellation analysis indicated that 6 and 19 genotypes of the H9 and H6 subtypes, respectively, belonged to the representative viruses. The Vietnamese viruses are genetically related to the previous isolates and those in neighboring countries, indicating their circulation in poultry after being introduced into Vietnam. The antigenicity of these subtypes was different from that of viruses isolated from wild birds. Antigenicity was more conserved in the H9 viruses than in the H6 viruses. Furthermore, a representative H9 LPAIV exhibited systemic replication in chickens, which was enhanced by coinfection with avian pathogenic Escherichia coli O2. Although H9 and H6 were classified as LPAIVs, their characterization indicated that their silent spread might significantly affect the poultry industry.
• Susceptibility of common dabbling and diving duck species to clade 2.3.2.1 H5N1 high pathogenicity avian influenza virus: an experimental infection study

  Kosuke SODA, Yukiko TOMIOKA, Tatsufumi USUI, Hiroichi OZAKI, Hiroshi ITO, Yasuko NAGAI, Naoki YAMAMOTO, Masatoshi OKAMATSU, Norikazu ISODA, Masahiro KAJIHARA, Yoshihiro SAKODA, Ayato TAKADA, Toshihiro ITO

  Journal of Veterinary Medical Science 85 (9) 942 - 949 0916-7250 2023
• Development of an Effective Oral Vaccine Dissemination Strategy against Classical Swine Fever for Wild Boar in Gifu Prefecture, Japan

  Satoshi Ito, Jaime Bosch, Cecilia Aguilar-Vega, Norikazu Isoda, Marta Martínez-Avilés, José Manuel Sánchez-Vizcaíno

  Transboundary and Emerging Diseases 2023 1865-1674 2023 

  In September 2018, classical swine fever (CSF) reemerged in Japan after more than a quarter of a century. After the frst no-tifcation on a pig farm, wild boars positive for CSF were found continuously in the surrounding area. Gifu was the frst prefecture in Japan to disseminate oral vaccines to wild boars in March 2019, with vaccines spread to approximately 14,000 sites between 2019 and 2020. While these diligent measures seemed to have shown some efectiveness, several vaccine spray sites remained without wild boar emergence. Based on the vaccine dissemination records from these periods, this study conducted a statistical analysis to propose more efective vaccine dissemination sites. First, a generalized linear mixed model was used to identify factors correlated with wild boar emergence. Ten, two spatial interpolation methods, inverse distance weighted (IDW) and Kriging, were adopted to create a probability map of wild boar emergence for the entire Gifu Prefecture. Te analysis showed a positive correlation between wild boar emergence and the appearance of raccoons, raccoon dogs, and crows as well as road density and wild boar distribution index. In particular, raccoon (OR: 1.83, 95%CI: 1.25–2.68, p < 0.001), raccoon dog (OR: 1.81, 95%CI: 1.25–2.66, p < 0.001), and medium level road density (OR: 1.56, 95%CI: 1.04–2.39, p 0.04) were strongly correlated with wild boar emergence. Te spatial interpolation approach resulted in better prediction accuracy for the Kriging method than for IDW by the root mean square error, but both approaches identifed a high wild boar appearance probability area in southeastern Gifu and a low appearance probability area in central Gifu. Here we have demonstrated a tool to efectively disperse oral vaccine to wildlife.
• Virological, pathological, and glycovirological investigations of an Ezo red fox and a tanuki naturally infected with H5N1 highly pathogenic avian influenza viruses in Hokkaido, Japan

  Takahiro Hiono, Daiki Kobayashi, Atsushi Kobayashi, Tamami Suzuki, Yuki Satake, Rio Harada, Keita Matsuno, Mariko Sashika, Hinako Ban, Maya Kobayashi, Keisuke Aoshima, Fumihito Takaya, Hiroko Fujita, Norikazu Isoda, Takashi Kimura, Yoshihiro Sakoda

  Virology 578 35 - 44 2023/01 [Refereed][Not invited]
   

  In winter/spring 2021-2022, high pathogenicity avian influenza viruses (HPAIVs) that are genetically closely related to each other were detected worldwide. In a public garden in Sapporo, Hokkaido, Japan, a crow die-off by HPAIV infection occurred from March 29 to May 18, 2022. During the event, H5N1 HPAIVs were isolated from an Ezo red fox (Vulpes vulpes schrencki) and a tanuki (Nyctereutes procyonoides albus) found in the same garden. The fox showed viral meningoencephalitis and moderate virus replication in the upper respiratory tract, whereas the tanuki showed viral conjunctivitis and secondary bacterial infection in the eyes accompanied with visceral larva migrans. Viruses isolated from the fox and the tanuki were genetically closely related to those isolated from crows in the same garden. Various α2-3 sialosides were found in the respiratory tracts of these canid mammals, consistent with HPAIV infections in these animals. This study highlighted the importance of monitoring HPAIV infections in wild carnivore mammals to detect the potential virus spreading in nature.
• Experimental and natural infections of white-tailed sea eagles (Haliaeetus albicilla) with high pathogenicity avian influenza virus of H5 subtype

  Yoshikazu Fujimoto, Kohei Ogasawara, Norikazu Isoda, Hitoshi Hatai, Kosuke Okuya, Yukiko Watanabe, Ayato Takada, Yoshihiro Sakoda, Keisuke Saito, Makoto Ozawa

  Frontiers in Microbiology 13 2022/10/03 

  White-tailed sea eagle (Haliaeetus albicilla), a regionally rare species of raptor, is threatened in several countries. To assess the risk of H5 high pathogenicity avian influenza (HPAI) viral infection in rare bird species, we performed experimental infections with a GS/GD96-lineage H5N6 HPAI virus of clade 2.3.4.4e in white-tailed sea eagles. Additionally, during the winter of 2020–2021 in Japan, we accidentally encountered a white-tailed sea eagle that had a fatal outcome due to natural infection with a GS/GD96-lineage H5N8 HPAI virus of clade 2.3.4.4b, allowing us to compare experimental and natural infections in the same rare raptor species. Our experiments demonstrated the susceptibility of white-tailed sea eagles to the GS/GD96-lineage H5 HPAI virus with efficient replication in systemic organs. The potential for the viruses to spread within the white-tailed sea eagle population through indirect transmission was also confirmed. Comprehensive comparisons of both viral distribution and histopathological observations between experimentally and naturally infected white-tailed sea eagles imply that viral replication in the brain is responsible for the disease severity and mortality in this species. These findings provide novel insights into the risk assessment of H5 HPAI viral infection in white-tailed sea eagles, proper diagnostic procedures, potential risks to artificially fed eagle populations and persons handling superficially healthy eagles, potential impact of intragastric infection on eagle outcomes, and possibility of severity of the disease being attributed to viral replication in the brain.
• Detection of New H5N1 High Pathogenicity Avian Influenza Viruses in Winter 2021-2022 in the Far East, Which Are Genetically Close to Those in Europe.

  Norikazu Isoda, Manabu Onuma, Takahiro Hiono, Ivan Sobolev, Hew Yik Lim, Kei Nabeshima, Hisako Honjyo, Misako Yokoyama, Alexander Shestopalov, Yoshihiro Sakoda

  Viruses 14 (10) 2022/09/30 

  Many high pathogenicity avian influenza (HPAI) cases in wild birds due to H5N1 HPAI virus (HPAIV) infection were reported in northern Japan in the winter of 2021-2022. To investigate the epidemiology of HPAIVs brought to Japan from surrounding areas, a genetic analysis of H5 HPAIVs isolated in northern Japan was performed, and the pathogenicity of the HPAIV in chickens was assessed by experimental infection. Based on the genetic analysis of the hemagglutinin gene, pathogenic viruses detected in northern Japan as well as one in Sakhalin, the eastern part of Russia, were classified into the same subgroup as viruses prevalent in Europe in the same season but distinct from those circulating in Asia in winter 2020-2021. High identities of all eight segment sequences of A/crow/Hokkaido/0103B065/2022 (H5N1) (Crow/Hok), the representative isolates in northern Japan in 2022, to European isolates in the same season could also certify the unlikeliness of causing gene reassortment between H5 HPAIVs and viruses locally circulating in Asia. According to intranasal challenge results in six-week-old chickens, 50% of the chicken-lethal dose of Crow/Hok was calculated as 104.5 times of the 50% egg-infectious dose. These results demonstrated that the currently prevalent H5 HPAIVs could spread widely from certain origins throughout the Eurasian continent, including Europe and the Far East, and implied a possibility that contagious viruses are gathered in lakes in the northern territory via bird migration. Active monitoring of wild birds at the global level is essential to estimate the geographical source and spread dynamics of HPAIVs.
• Turkeys possess diverse Siaα2-3Gal glycans that facilitate their dual susceptibility to avian influenza viruses isolated from ducks and chickens

  Daiki Kobayashi, Takahiro Hiono, Osamu Ichii, Shoko Nishihara, Sayaka Takase-Yoden, Kazuo Yamamoto, Hiroto Kawashima, Norikazu Isoda, Yoshihiro Sakoda

  Virus Research 315 0168-1702 2022/07/02 [Refereed][Not invited]
   

  Avian influenza viruses (AIVs) circulating in wild ducks are rarely transmitted directly to chickens. Previous studies demonstrated that chickens possess fucosylated and/or sulfated α2,3 sialosides on their tracheal epithelia, whereas intestinal epithelia of ducks express canonical α2,3 sialosides. Turkeys, the third major poultry species in the world, are known to show broad susceptibility to various avian influenza viruses. To elucidate the molecular basis of the broad susceptibility of turkeys to duck and chicken AIVs, we characterized various receptors for AIVs on their tissues. The experimental infection of turkeys demonstrated their dual susceptibility to duck and chicken AIVs. Further, comprehensive histochemical analyses using lectins, anti-glycan antibodies, and recombinant hemagglutinins, combined with glycosidase digestions, identified the presence of fucosylated and/or sulfated in addition to canonical α2,3 sialosides on their respiratory epithelia. The receptor distributions in turkeys were consistent with their dual susceptibility to duck and chicken AIVs. Also, our findings suggested the potential roles of turkeys in interspecies transmission of AIVs from ducks to chickens.
• ANTIBIOGRAMS AND VIRULENCE GENES OF ESCHERICHIA COLI AND SALMONELLA SP FROM FARM PIGS IN CENTRAL THAILAND

  Pornthip Chompook, Apiradee Intarapak, Kanjana Changkaew, Ruttana Pachanon, Apichart Suwannachairob, Chie Nakajima, Yasuhiko Suzuki, Orasa Suthienkul, Norikazu Isoda

  Southeast Asian Journal of Tropical Medicine and Public Health 53 (3) 322 - 344 0125-1562 2022/05/19 

  The increasing global trend of antimicrobial resistance (AMR), especially in pig production, can pose a threat to human health. The study investigated the prevalence of AMR in Escherichia coli and Salmonella serovars from farm pigs in central Thailand. E. coli and Salmonella serovars from pig stool specimens were identified by standard methods, susceptibility to antimicrobials by the disk agar diffusion method and pathogenic E. coli virulence genes by multiplex PCR. E. coli isolates harboring astA were the most predominant (27%), followed by eaeA (9%). E. coli isolates with virulence genes were present significantly more in pigs with loose stool (70%) than those with normal stool (40%) (p-value <0.001). The overall prevalence of Salmonella sp isolates in pigs was 44.3%, with S. Agona serovar predominant (27%). E. coli and Salmonella sp isolates demonstrated predominant resistance to penicillin (71 and 79% respectively), followed by tetracycline (67.5 and 73.1%), then streptomycin (52 and 51%), and sulfonamide (45 and 36%), with multidrug resistance (MDR) (≥3 antimicrobial classes) in 66 and 74% E. coli and Salmonella sp isolates, respectively. E. coli harboring a single astA was significantly associated with MDR phenotype compared to those without any virulence gene (odds ratio = 2.16, 95% confidence interval: 1.09-4.29). In conclusion, the study indicates that farm pigs in central Thailand could be potential sources of foodborne MDR E. coli and Salmonella sp.
• Risk profile of low pathogenicity avian influenza virus infections in farms in southern Vietnam.

  Kien Trung LE, Norikazu Isoda, Lam Thanh Nguyen, Duc-Huy Chu, Long Van Nguyen, Minh Quang Phan, Diep Thi Nguyen, Tien Ngoc Nguyen, Tien Ngoc Tien, Tung Thanh LE, Takahiro Hiono, Keita Matsuno, Masatoshi Okamatsu, Yoshihiro Sakoda

  The Journal of veterinary medical science 84 (6) 860 - 868 2022/05/13 

  The impact of low pathogenicity avian influenza (LPAI) has been confirmed mainly in farms. Unlike apparent losses caused by the high pathogenicity avian influenza (HPAI), the LPAI impact has been hardly evaluated due to underestimating its spread and damage. In 2019, a questionnaire study was conducted in southern Vietnam to identify the specific risk factors of LPAI virus (LPAIV) circulation and to find associations between husbandry activities and LPAI prevalence. A multilevel regression analysis indicated that keeping Muscovy ducks during farming contributed to LPAIV positivity [Odds ratio=208.2 (95% confidence interval: 13.4-1.1×104)]. In cluster analysis, farmers willing to report avian influenza (AI) events and who agreed with the local AI control policy had a slightly lower risk for LPAIV infection although there was no significance in the correlation between farmer characteristics and LPAI occurrence. These findings indicated that keeping Muscovy ducks without appropriate countermeasures might increase the risk of LPAIV infection. Furthermore, specific control measures at the local level are effective for LPAIV circulation, and the improvement of knowledge about biosecurity and attitude contributes to reducing LPAI damage.
• Assessment of ameliorative effects of organic dietary interventions on neonicotinoid exposure rates in a Japanese population.

  Collins Nimako, Takahiro Ichise, Hiroshi Hasegawa, Osei Akoto, Nathaniel O Boadi, Kumiko Taira, Kazutoshi Fujioka, Norikazu Isoda, Shouta M M Nakayama, Mayumi Ishizuka, Yoshinori Ikenaka

  Environment international 162 107169 - 107169 2022/04 

  Neonicotinoid insecticides (NNIs) are a popular class of insecticides used in various pest management regimens worldwide. Biomonitoring studies continuously report high exposure rates of NNIs in various human populations across the globe. Yet, there is no validated countermeasure for combating the recent exponential rise in NNI exposure rates observed in human populations. The current study assessed the impacts of organic dietary interventions on NNI exposure rates in a Japanese population. A total of 103 volunteers were recruited into the study. Subjects were either served with Organic diets for 5 and 30 days or conventional diets. A total of 919 repeated urine samples were collected from the participants and then subjected to LC-MS/MS analysis to determine urinary concentrations of 7 NNIs parent compounds and an NNI metabolite. Eight NNIs were detected; with a decreasing detection frequency (%Dfs) pattern; desmethyl-acetamiprid (dm-ACE) (64.96%) > dinotefuran (52.12%), imidacloprid (39.61%) > clothianidin (33.95%) > thiamethoxam (28.51%) > acetamiprid (12.62%) > nitenpyram (5.33%) > thiacloprid (2.83%). Dinotefuran, dm-ACE, and clothianidin recorded the highest concentrations in the subjects. The %Df of NNIs in the 5-days or 30-days organic diet group were lower than those of the conventional diet consumers. The organic diet group showed lower rates of multiple NNI exposures than those of the conventional diet consumers. The mean and median cumulative levels of NNIs (median IMIeq) were significantly lower in the organic diet group than the conventional diet group (p < 0.0001). The estimated daily intakes (EDIs) of NNIs were higher in adults than children, but less than 1% of NNI cRfDs, except for clothianidin, which exhibited a %cRfD of 1.32 in children. Compared to the conventional diet group, the 5- and 30-day organic dietary intervention showed drastic reductions in NNI EDIs. Findings from the present study give credence to organic dietary interventions as potential ameliorative strategies for NNI exposure rates in human populations.
• Strategies for fighting pandemic virus infections: Integration of virology and drug delivery.

  Takashi Nakamura, Norikazu Isoda, Yoshihiro Sakoda, Hideyoshi Harashima

  Journal of controlled release : official journal of the Controlled Release Society 343 361 - 378 2022/03 

  Respiratory viruses have sometimes resulted in worldwide pandemics, with the influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) being major participants. Long-term efforts have made it possible to control the influenza virus, but seasonal influenza continues to take many lives each year, and a pandemic influenza virus sometimes emerges. Although vaccines for coronavirus disease 2019 (COVID-19) have been developed, we are not yet able to coexist with the SARS-CoV-2. To overcome such viruses, it is necessary to obtain knowledge about international surveillance systems, virology, ecology and to determine that immune responses are effective. The information must then be transferred to drugs. Delivery systems would be expected to contribute to the rational development of drugs. In this review, virologist and drug delivery system (DDS) researchers discuss drug delivery strategies, especially the use of lipid-based nanocarriers, for fighting to respiratory virus infections.
• Endemic infections of bovine viral diarrhea virus genotypes 1b and 2a isolated from cattle in Japan between 2014 and 2020.

  Asami Nishimori, Shizuka Hirose, Saho Ogino, Kiyohiko Andoh, Norikazu Isoda, Yoshihiro Sakoda

  The Journal of veterinary medical science 84 (2) 228 - 232 2022/02/10 

  Bovine viral diarrhea virus (BVDV) is a causative agent of bovine viral diarrhea. In Japan, a previous study reported that subgenotype 1b viruses were predominant until 2014. Because there is little information regarding the recent epidemiological status of BVDV circulating in Japan, we performed genetic characterization of 909 BVDV isolates obtained between 2014 and 2020. We found that 657 and 252 isolates were classified as BVDV-1 and BVDV-2, respectively, and that they were further subdivided into 1a (35 isolates, 3.9%), 1b (588, 64.7%), 1c (34, 3.7%), and 2a (252, 27.7%). Phylogenetic analysis using entire E2 coding sequence revealed that a major domestic cluster in Japan among BVDV-1b and 2a viruses were unchanged from a previous study conducted from 2006 to 2014. These results provide updated information concerning the epidemic strain of BVDV in Japan, which would be helpful for appropriate vaccine selection.
• Antiviral Effects of 5-Aminolevulinic Acid Phosphate against Classical Swine Fever Virus: In Vitro and In Vivo Evaluation.

  Shizuka Hirose, Norikazu Isoda, Loc Tan Huynh, Taksoo Kim, Keiichiro Yoshimoto, Tohru Tanaka, Kenjiro Inui, Takahiro Hiono, Yoshihiro Sakoda

  Pathogens (Basel, Switzerland) 11 (2) 2022/01/27 

  The inhibitory effects of 5-aminolevulinic acid phosphate (5-ALA), an important amino acid for energy production in the host, against viral infections were previously reported. Here, the antiviral effects of 5-ALA against classical swine fever virus (CSFV) belonging to the genus Pestivirus in the Flaviviridae family and its possible mechanisms were investigated. CSFV replication was suppressed in swine cells supplemented with 5-ALA or its metabolite, protoporphyrin IX (PPIX). The infectivity titer of CSFV was decreased after mixing with PPIX extracellularly. In addition, the activities of the replication cycle were decreased in the presence of PPIX based on the CSFV replicon assay. These results showed that PPIX exerted antiviral effects by inactivating virus particles and inhibiting the replication cycle. To evaluate the in vivo efficacy of 5-ALA, pigs were supplemented daily with 5-ALA for 1 week before virus inoculation and then inoculated with a virulent CSFV strain at the 107.0 50% tissue culture infectious dose. The clinical scores of the supplemented group were significantly lower than those of the nonsupplemented group, whereas the virus growth was not. Taken together, 5-ALA showed antiviral effects against CSFV in vitro, and PPIX played a key role by inactivating virus particles extracellularly and inhibiting the replication cycle intracellularly.
• A systematic approach to illuminate a new hot spot of avian influenza virus circulation in South Vietnam, 2016-2017.

  Kien Trung Le, Mark A Stevenson, Norikazu Isoda, Lam Thanh Nguyen, Duc-Huy Chu, Tien Ngoc Nguyen, Long Van Nguyen, Tien Ngoc Tien, Tung Thanh Le, Keita Matsuno, Masatoshi Okamatsu, Yoshihiro Sakoda

  Transboundary and emerging diseases 2021/11/04 

  In South Vietnam, live bird markets (LBMs) are key in the value chain of poultry products and spread of avian influenza virus (AIV) although they may not be the sole determinant of AIV prevalence. For this reason, a risk analysis of AIV prevalence was conducted accounting for all value chain factors. A cross-sectional study of poultry flock managers and poultry on backyard farms, commercial (high biosecurity) farms, LBMs and poultry delivery stations (PDSs) in four districts of Vinh Long province was conducted between December 2016 and August 2017. A total of 3597 swab samples were collected from birds from 101 backyard farms, 50 commercial farms, 58 sellers in LBMs and 19 traders in PDSs. Swab samples were submitted for AIV isolation. At the same time a questionnaire was administered to flock managers asking them to provide details of their knowledge, attitude and practices related to avian influenza. Multiple correspondence analysis and a mixed-effects multivariable logistic regression model were developed to identify enterprise and flock manager characteristics that increased the risk of AIV positivity. A total of 274 birds were positive for AIV isolation, returning an estimated true prevalence of 7.6% [95% confidence interval (CI): 6.8%-8.5%]. The odds of a bird being AIV positive if it was from an LBM or PDS were 45 (95% CI: 3.4-590) and 25 (95% CI: 1.4-460), respectively, times higher to the odds of a bird from a commercial poultry farm being AIV positive. The odds of birds being AIV positive for respondents with a mixed (uncertain or inconsistent) level and a low level of knowledge about AI were 5.0 (95% CI: 0.20-130) and 3.5 (95% CI: 0.2-62), respectively, times higher to the odd of birds being positive for respondents with a good knowledge of AI. LBMs and PDSs should receive specific emphasis in AI control programs in Vietnam. Our findings provide evidence to support the hypothesis that incomplete respondent knowledge of AI and AIV spread mechanism were associated with an increased risk of AIV positivity. Delivery of education programs specifically designed for those in each enterprise will assist in this regard. The timing and frequency of delivery of education programs are likely to be important if the turnover of those working in LBMs and PDSs is high.
• Establishment of a mouse- and egg-adapted strain for the evaluation of vaccine potency against H3N2 variant influenza virus in mice.

  Enkhbold Bazarragchaa, Takahiro Hiono, Norikazu Isoda, Hirotaka Hayashi, Masatoshi Okamatsu, Yoshihiro Sakoda

  The Journal of veterinary medical science 83 (11) 1694 - 1701 2021/10/31 

  Sporadic spreads of swine-origin influenza H3N2 variant (H3N2v) viruses were reported in humans, resulting in 437 human infections between 2011 and 2021 in the USA. Thus, an effective vaccine is needed to better control a potential pandemic for these antigenically distinct viruses from seasonal influenza. In this study, a candidate vaccine strain with efficient growth capacity in chicken embryos was established through serial blind passaging of A/Indiana/08/2011 (H3N2)v in mice and chicken embryos. Seven amino acid substitutions (M21I in PA; A138T, N165K, and V226A in HA; S312L in NP; T167I in M1; G62A in NS1 proteins) were found in the passaged viruses without a major change in the antigenicity. This mouse- and egg-adapted virus was used as a vaccine and challenge strain in mice to evaluate the efficacy of the H3N2v vaccine in different doses. Antibodies with high neutralizing titers were induced in mice immunized with 100 µg of inactivated whole-virus particles, and those mice were significantly protected from the challenge of homologous strain. The findings indicated that the established strain in the study was useful for vaccine study in mouse models.
• Characteristics of Classical Swine Fever Virus Variants Derived from Live Attenuated GPE- Vaccine Seed.

  Taksoo Kim, Loc Tan Huynh, Shizuka Hirose, Manabu Igarashi, Takahiro Hiono, Norikazu Isoda, Yoshihiro Sakoda

  Viruses 13 (8) 2021/08/23 

  The GPE- strain is a live attenuated vaccine for classical swine fever (CSF) developed in Japan. In the context of increasing attention for the differentiating infected from vaccinated animals (DIVA) concept, the achievement of CSF eradication with the GPE- proposes it as a preferable backbone for a recombinant CSF marker vaccine. While its infectious cDNA clone, vGPE-, is well characterized, 10 amino acid substitutions were recognized in the genome, compared to the original GPE- vaccine seed. To clarify the GPE- seed availability, this study aimed to generate and characterize a clone possessing the identical amino acid sequence to the GPE- seed. The attempt resulted in the loss of the infectious GPE- seed clone production due to the impaired replication by an amino acid substitution in the viral polymerase NS5B. Accordingly, replication-competent GPE- seed variant clones were produced. Although they were mostly restricted to propagate in the tonsils of pigs, similarly to vGPE-, their type I interferon-inducing capacity was significantly lower than that of vGPE-. Taken together, vGPE- mainly retains ideal properties for the CSF vaccine, compared with the seed variants, and is probably useful in the development of a CSF marker vaccine.
• Prevalence and Multidrug-Resistance Salmonella in Swine Production Chain in a Central Province, Thailand.

  Kaknokrat Chonsin, Ruchirada Changkwanyeun, Achiraya Siriphap, Apiradee Intarapuk, Watsawan Prapasawat, Kanjana Changkaew, Chaiwat Pulsrikan, Norikazu Isoda, Chie Nakajima, Yasuhiko Suzuki, Orasa Suthienkul

  Journal of food protection 84 (12) 2174 - 2184 2021/08/19 

  Salmonella causes foodborne disease outbreaks worldwide and raises considerable concerns about public health and economic losses. To determine prevalence, serovar, antimicrobial resistance (AMR) patterns, and extended-spectrum beta-lactamase (ESBL) genes, the present cross-sectional study collected a total of 418 fecal, carcass (three slaughterhouses), pork and cutting board (four markets) samples from a province in central Thailand in 2017 and 2018. Results showed that 65.1% (272/418) of samples were positive for Salmonella. The percentage of Salmonella positive samples from markets (88.8%; 158/178) was significantly higher than those from slaughterhouses (47.5%; 114/240) ( P<0.05 ). In total, 1,030 isolates were identified; of these, 409 were assigned to 45 serovars with S. Rissen (20%; 82/409) being the most common. New serovars of Thai isolates, S. Cannstatt and S. Braubach, were identified in market and slaughterhouse samples, respectively. AMR of Salmonella isolates showed that 73.9% (133/180) of 19 different serovars exhibited multidrug resistance (MDR). Screening for ESBL production showed that 10.3% (41/399) of isolates were ESBL positive. ESBL-producing Salmonella isolates in market samples (75.6%; 31/41) were significantly higher than those in slaughterhouse samples (24.4%; 10/41) ( P<0.05 ). In market samples, 77.4% (24/31) were isolated from pork and 22.6% (7/31) from cutting boards. Nine ESBL-producing isolates carried single type ESBL genes bla TEM (9.8%; 4/41) or bla CTX-M (12.2%; 5/41), while 11 (26.8%) carried both bla TEM and bla CTX-M . No ESBL-producing Salmonella isolate carried the gene bla SHV . Results suggest that pigs, their flesh, and cutting boards could be reservoirs for widespread MDR, ESBL-producing Salmonella outbreak across the food chain.
• Transmission Dynamics of Bovine Viral Diarrhea Virus in Hokkaido, Japan by Phylogenetic and Epidemiological Network Approaches.

  Shizuka Hirose, Kosuke Notsu, Satoshi Ito, Yoshihiro Sakoda, Norikazu Isoda

  Pathogens (Basel, Switzerland) 10 (8) 2021/07/21 

  Bovine viral diarrhea (BVD) caused by BVD virus (BVDV) leads to economic loss worldwide. Cattle that are persistently infected (PI) with BVDV are known to play an important role in viral transmission in association with the animal movement, as they shed the virus during their lifetime. In this research, the "hot spot" for BVD transmission was estimated by combining phylogenetic and epidemiological analyses for PI cattle and cattle that lived together on BVDV affected farms in Tokachi district, Hokkaido prefecture, Japan. Viral isolates were genetically categorized into BVDV-1a, 1b, and 2a, based on the nucleotide sequence of the entire E2 region. In BVDV genotype 1, subgenotype b (BVDV-1b), cluster I was identified as the majority in Tokachi district. Network analysis indicated that 12 of the 15 affected farms had cattle movements from other facilities (PI-network) and farms affected with BVDV-1b cluster I consisted of a large network. It was implied that the number of cattle movements themselves would be a risk of BVD transmission, using the PageRank algorithm. Therefore, these results demonstrate that cattle movements would contribute to disease spread and the combination of virological and epidemiological analysis methods would be beneficial in determining possible virus transmission routes.
• Immunization Coverage and Antibody Retention against Rabies in Domestic Dogs in Lusaka District, Zambia.

  Chiho Kaneko, Michihito Sasaki, Ryosuke Omori, Ryo Nakao, Chikako Kataoka-Nakamura, Ladslav Moonga, Joseph Ndebe, Walter Muleya, Edgar Simulundu, Bernard M Hang'ombe, George Dautu, Masahiro Kajihara, Akina Mori-Kajihara, Yongjin Qiu, Naoto Ito, Herman M Chambaro, Chihiro Sugimoto, Hideaki Higashi, Ayato Takada, Hirofumi Sawa, Aaron S Mweene, Norikazu Isoda

  Pathogens (Basel, Switzerland) 10 (6) 2021/06/11 

  Rabies remains endemic in Zambia. Despite conducting canine vaccinations in Lusaka district, the vaccination coverage and actual seropositivity in the dog population in Lusaka district are rarely evaluated. This study estimated the seropositivity-based immunization coverage in the owned dog population in Lusaka district using the expanded program on immunization cluster survey method. The time-series trend of neutralizing antibodies against rabies in vaccinated dogs was also evaluated. Of 366 dogs in 200 dog-owning households in Lusaka district, blood samples were collected successfully from 251 dogs. In the sampled dogs, 42.2% (106/251) had an antibody titer ≥0.5 IU/mL. When the 115 dogs whose blood was not collected were assumed to be seronegative, the minimum immunization coverage in Lusaka district's owned dog population was estimated at 29.0% (95% confidence interval: 22.4-35.5). It was also found that a single vaccination with certified vaccines is capable of inducing protective levels of antibodies. In contrast, higher antibody titers were observed in multiple-vaccinated dogs than in single-vaccinated dogs, coupled with the observation of a decline in antibody titer over time. These results suggest the importance of continuous booster immunization to maintain herd immunity and provide useful information to plan mass vaccination against rabies in Zambia.
• Domestic dog demographics and estimates of canine vaccination coverage in a rural area of Zambia for the elimination of rabies.

  Chiho Kaneko, Ryosuke Omori, Michihito Sasaki, Chikako Kataoka-Nakamura, Edgar Simulundu, Walter Muleya, Ladslav Moonga, Joseph Ndebe, Bernard M Hang'ombe, George Dautu, Yongjin Qiu, Ryo Nakao, Masahiro Kajihara, Akina Mori-Kajihara, Herman M Chambaro, Hideaki Higashi, Chihiro Sugimoto, Hirofumi Sawa, Aaron S Mweene, Ayato Takada, Norikazu Isoda

  PLoS neglected tropical diseases 15 (4) e0009222  2021/04 

  BACKGROUND: An estimated 75% or more of the human rabies cases in Africa occur in rural settings, which underscores the importance of rabies control in these areas. Understanding dog demographics can help design strategies for rabies control and plan and conduct canine mass vaccination campaigns effectively in African countries. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional survey was conducted to investigate domestic dog demographics in Kalambabakali, in the rural Mazabuka District of Zambia. The population of ownerless dogs and the total achievable vaccination coverage among the total dog population was estimated using the capture-recapture-based Bayesian model by conducting a canine mass vaccination campaign. This study revealed that 29% of the domestic dog population was under one year old, and 57.7% of those were under three months old and thus were not eligible for the canine rabies vaccination in Zambia. The population growth was estimated at 15% per annum based on the cross-sectional household survey. The population of ownerless dogs was estimated to be small, with an ownerless-to-owned-dog ratio of 0.01-0.06 in the target zones. The achieved overall vaccination coverage from the first mass vaccination was estimated 19.8-51.6%. This low coverage was principally attributed to the owners' lack of information, unavailability, and dog-handling difficulties. The follow-up mass vaccination campaign achieved an overall coverage of 54.8-76.2%. CONCLUSIONS/SIGNIFICANCE: This paper indicates the potential for controlling canine rabies through mass vaccination in rural Zambia. Rabies education and responsible dog ownership are required to achieve high and sustainable vaccination coverage. Our findings also propose including puppies below three months old in the target population for rabies vaccination and emphasize that securing an annual enforcement of canine mass vaccination that reaches 70% coverage in the dog population is necessary to maintain protective herd immunity.
• Efficacy of Oral Vaccine against Classical Swine Fever in Wild Boar and Estimation of the Disease Dynamics in the Quantitative Approach.

  Enkhbold Bazarragchaa, Norikazu Isoda, Taksoo Kim, Madoka Tetsuo, Satoshi Ito, Keita Matsuno, Yoshihiro Sakoda

  Viruses 13 (2) 2021/02/20 

  Classical swine fever virus (CSFV) in the wild boar population has been spreading in Japan, alongside outbreaks on pigs, since classical swine fever (CSF) reemerged in September 2018. The vaccination using oral bait vaccine was initially implemented in Gifu prefecture in March 2019. In the present study, antibodies against CSFV in wild boar were assessed in 1443 captured and dead wild boars in Gifu prefecture. After the implementation of oral vaccination, the increase of the proportion of seropositive animals and their titer in wild boars were confirmed. Quantitative analysis of antigen and antibodies against CSFV in wild boar implies potential disease diversity in the wild boar population. Animals with status in high virus replication (Ct < 30) and non- or low-immune response were confirmed and were sustained at a certain level after initial oral vaccination. Through continuous vaccination periods, the increase of seroprevalence among wild boar and the decrease of CSFV-positive animals were observed. The epidemiological analysis based on the quantitative virological outcomes could provide more information on the efficacy of oral vaccination and dynamics of CSF in the wild boar population, which will help to improve the implementation of control measures for CSF in countries such as Japan and neighboring countries.
• A New Variant Among Newcastle Disease Viruses Isolated in the Democratic Republic of the Congo in 2018 and 2019.

  Augustin T Twabela, Lam Thanh Nguyen, Justin Masumu, Patrick Mpoyo, Serge Mpiana, Julienne Sumbu, Masatoshi Okamatsu, Keita Matsuno, Norikazu Isoda, Bianca Zecchin, Isabella Monne, Yoshihiro Sakoda

  Viruses 13 (2) 2021/01/20 

  Newcastle disease (ND) is a highly transmissible and devastating disease that affects poultry and wild birds worldwide. Comprehensive knowledge regarding the characteristics and epidemiological factors of the ND virus (NDV) is critical for the control and prevention of ND. Effective vaccinations can prevent and control the spread of the NDV in poultry populations. For decades, the Democratic Republic of the Congo (DRC) has reported the impacts of ND on commercial and traditional poultry farming systems. The reports were preliminary clinical observations, and few cases were confirmed in the laboratory. However, data on the phylogenetic, genetic, and virological characteristics of NDVs circulating in the DRC are not available. In this study, the whole-genome sequences of three NDV isolates obtained using the next-generation sequencing method revealed two isolates that were a new variant of NDV, and one isolate that was clustered in the subgenotype VII.2. All DRC isolates were velogenic and were antigenically closely related to the vaccine strains. Our findings reveal that despite the circulation of the new variant, ND can be controlled in the DRC using the current vaccine. However, epidemiological studies should be conducted to elucidate the endemicity of the disease so that better control strategies can be implemented.
• Potency of an Inactivated Influenza Vaccine against a Challenge with A/Swine/Missouri/A01727926/2015 (H4N6) in Mice for Pandemic Preparedness.

  Hirotaka Hayashi, Norikazu Isoda, Enkhbold Bazarragchaa, Naoki Nomura, Keita Matsuno, Masatoshi Okamatsu, Hiroshi Kida, Yoshihiro Sakoda

  Vaccines 8 (4) 2020/12/16 

  H4 influenza viruses have been isolated from birds across the world. In recent years, an H4 influenza virus infection has been confirmed in pigs. Pigs play an important role in the transmission of influenza viruses to human hosts. Therefore, it is important to develop a new vaccine in the case of an H4 influenza virus infection in humans, considering that this virus has a different antigenicity from seasonal human influenza viruses. In this study, after selecting vaccine candidate strains based on their antigenic relation to one of the pig isolates, A/swine/Missouri/A01727926/2015 (H4N6) (MO/15), an inactivated whole-particle vaccine was prepared from A/swan/Hokkaido/481102/2017 (H4N6). This vaccine showed high immunogenicity in mice, and the antibody induced by the vaccine showed high cross-reactivity to the MO/15 virus. This vaccine induced sufficient neutralizing antibodies and mitigated the effects of an MO/15 infection in a mouse model. This study is the first to suggest that an inactivated whole-particle vaccine prepared from an influenza virus isolated from wild birds is an effective countermeasure in case of a future influenza pandemic caused by the H4 influenza virus.
• Re-Invasion of H5N8 High Pathogenicity Avian Influenza Virus Clade 2.3.4.4b in Hokkaido, Japan, 2020.

  Norikazu Isoda, Augustin T Twabela, Enkhbold Bazarragchaa, Kohei Ogasawara, Hirotaka Hayashi, Zu-Jyun Wang, Daiki Kobayashi, Yukiko Watanabe, Keisuke Saito, Hiroshi Kida, Yoshihiro Sakoda

  Viruses 12 (12) 2020/12/14 

  Global dispersion of high pathogenicity avian influenza (HPAI), especially that caused by H5 clade 2.3.4.4, has threatened poultry industries and, potentially, human health. An HPAI virus, A/northern pintail/Hokkaido/M13/2020 (H5N8) (NP/Hok/20) belonging to clade 2.3.4.4b, was isolated from a fecal sample collected at a lake in Hokkaido, Japan where migratory birds rested, October 2020. In the phylogenetic trees of all eight gene segments, NP/Hok/20 fell into in the cluster of European isolates in 2020, but was distinct from the isolates in eastern Asia and Europe during the winter season of 2017-2018. The antigenic cartography indicates that the antigenicity of NP/Hok/20 was almost the same as that of previous isolates of H5 clade 2.3.4.4b, whereas the antigenic distances from NP/Hok/20 to the representative strains in clade 2.3.4.4e and to a strain in 2.3.4 were apparently distant. These data imply that HPAI virus clade 2.3.4.4b should have been delivered by bird migration despite the intercontinental distance, although it was not defined whether NP/Hok/20 was transported from Europe via Siberia where migratory birds nest in the summer season. Given the probability of perpetuation of transmission in the northern territory, periodic updates of intensive surveys on avian influenza at the global level are essential to prepare for future outbreaks of the HPAI virus.
• Evaluation of Baloxavir Marboxil and Peramivir for the Treatment of High Pathogenicity Avian Influenza in Chickens.

  Augustin Twabela, Masatoshi Okamatsu, Keita Matsuno, Norikazu Isoda, Yoshihiro Sakoda

  Viruses 12 (12) 2020/12/08 

  Control measures in the case of high pathogenicity avian influenza (HPAI) outbreaks in poultry include culling, surveillance, and biosecurity; wild birds in captivity may also be culled, although some rare bird species should be rescued for conservation. In this study, two anti-influenza drugs, baloxavir marboxil (BXM) and peramivir (PR), used in humans, were examined in treating HPAI in birds, using chickens as a model. Chickens were infected with H5N6 HPAI virus and were treated immediately or 24 h from challenge with 20 mg/kg BXM or PR twice a day for five days. As per our findings, BXM significantly reduced virus replication in organs and provided full protection to chickens compared with that induced by PR. In the 24-h-delayed treatment, neither drug completely inhibited virus replication nor ensured the survival of infected chickens. A single administration of 2.5 mg/kg of BXM was determined as the minimum dose required to fully protect chickens from HPAI virus; the concentration of baloxavir acid, the active form of BXM, in chicken blood at this dose was sufficient for a 48 h antiviral effect post-administration. Thus, these data can be a starting point for the use of BXM and PR in treating captive wild birds infected with HPAI virus.
• 時空間解析を用いた日本における野生イノシシ群での豚熱感染拡大評価

  磯田 典和, 馬場 開陸, 伊藤 聡, 伊藤 貢, 迫田 義博, 蒔田 浩平

  獣医疫学雑誌 獣医疫学会 24 (2) 81 - 82 1343-2583 2020/12
• 野生イノシシにおけるCSF感染拡大様式評価のための地域2ヵ月期間有病率推定

  馬場 開陸, 磯田 典和, 伊藤 聡, 伊藤 貢, 迫田 義博, 蒔田 浩平

  獣医疫学雑誌 獣医疫学会 24 (2) 83 - 84 1343-2583 2020/12
• Molecular analysis of streptomycin-resistance associating genes in Mycobacterium tuberculosis isolates from Nepal.

  Dipti Shrestha, Bhagwan Maharjan, Nan Aye Thida Oo, Norikazu Isoda, Chie Nakajima, Yasuhiko Suzuki

  Tuberculosis (Edinburgh, Scotland) 125 101985 - 101985 2020/12 

  Mutation in rpsL (encoding ribosomal protein S12), rrs (encoding 16S ribosomal RNA) and gidB (encoding 7-methylguanosine methyltransferase) are associated with resistance to streptomycin (STR), which is used for the treatment of multi-drug resistant tuberculosis (MDR-TB) in Nepal. The aim of our study is to analyze the correlation between mutations in the target genes and STR-resistance in 197 Mycobacterium tuberculosis (MTB) isolates from Nepal. Mutations in rpsL was harbored by 65.9% of isolates, in which the most common mutation in rpsL is caused by K43R (58.8%) and were significantly associated with Beijing genotype (P < 0.001). About 13.2% of isolates harbored mutations in two highly mutable regions of rrs, the 530 loop and the 912 region. About 13.2% of gidB mutants do not show any mutation in rpsL and rrs, which might suggest the role of gidB mutations in STR-resistance in MTB. In addition, 5.6% of isolates do not show any mutations in three genes examined, suggesting the involvement of other mechanism in STR-resistance in MTB. Our findings can be implemented for the establishment of molecular STR-susceptibility testing, in which tuberculosis can be treated with appropriate drugs and can improve control strategies for DR-TB.
• 2016-2017年のベトナム南部での疫学的研究から明らかになった、鳥インフルエンザウイルスの新たなホットスポットの意義(The implication of a new hot spot of avian influenza based on epidemiological study in southern Vietnam in 2016-2017)

  Le Trung Kien, 磯田 典和, Nguyen Thanh Lam, Chu Duc-Huy, Tien Tien Ngoc, 松野 啓太, 岡松 正敏, 喜田 宏, 迫田 義博, 北海道大人獣共通感染症リサーチセンター/国際協働ユニット

  日本獣医学会学術集会講演要旨集 163回 232 - 232 1347-8621 2020/10
• ウイルス学的解析および疫学的解析を用いた北海道十勝地方における牛ウイルス性下痢ウイルスの伝播経路解明

  廣瀬 静香, 野津 昂亮, 松野 啓太, 岡松 正敏, 川本 恵子, 磯田 典和, 迫田 義博

  日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 163回 236 - 236 1347-8621 2020/10
• 日本の岐阜県にてイノシシから採取した血中古典的ブタ熱ウイルス抗原と抗体に関する定量分析(Quantitative analysis of antigen and antibody of classical swine fever virus in wild boar sera collected in Gifu prefecture, Japan)

  Enkhbold Bazarragchaa, 金 琢洙, 哲翁 まどか, 磯田 典和, 松野 啓太, 迫田 義博, 北海道大人獣共通感染症リサーチセンター/国際協働ユニット

  日本獣医学会学術集会講演要旨集 163回 243 - 243 1347-8621 2020/10
• Oral Supplementation of the Vitamin D Metabolite 25(OH)D3 Against Influenza Virus Infection in Mice.

  Hirotaka Hayashi, Masatoshi Okamatsu, Honami Ogasawara, Naoko Tsugawa, Norikazu Isoda, Keita Matsuno, Yoshihiro Sakoda

  Nutrients 12 (7) 2020/07/05 

  Vitamin D is a fat-soluble vitamin that is metabolized by the liver into 25-hydroxyvitamin D [25(OH)D] and then by the kidney into 1,25-dihydroxyvitamin D [1,25(OH)2D], which activates the vitamin D receptor expressed in various cells, including immune cells, for an overall immunostimulatory effect. Here, to investigate whether oral supplementation of 25-hydroxyvitamin D3 [25(OH)D3], a major form of vitamin D metabolite 25(OH)D, has a prophylactic effect on influenza A virus infection, mice were fed a diet containing a high dose of 25(OH)D3 and were challenged with the influenza virus. In the lungs of 25(OH)D3-fed mice, the viral titers were significantly lower than in the lungs of standardly fed mice. Additionally, the proinflammatory cytokines IL-5 and IFN-γ were significantly downregulated after viral infection in 25(OH)D3-fed mice, while anti-inflammatory cytokines were not significantly upregulated. These results indicate that 25(OH)D3 suppresses the production of inflammatory cytokines and reduces virus replication and clinical manifestations of influenza virus infection in a mouse model.
• Risk Assessment of African Swine Fever Virus Exposure to Sus scrofa in Japan Via Pork Products Brought in Air Passengers' Luggage.

  Satoshi Ito, Jaime Bosch, Cristina Jurado, José Manuel Sánchez-Vizcaíno, Norikazu Isoda

  Pathogens (Basel, Switzerland) 9 (4) 2020/04/20 

  In recent years, African swine fever (ASF) has become prevalent in many areas, including Asia. The repeated detection of the ASF virus (ASFV) genome in pork products brought in air passenger's luggage (PPAP) was also reported from Japanese airports. In the present study, the risk of ASFV exposure to susceptible hosts in Japan via three different pathways was assessed. Two quantitative stochastic risk assessment models were built to estimate the annual probability of ASFV exposure to domestic pigs, which could be attributed to foreign job trainees or foreign tourists. A semi-quantitative stochastic model was built to assess the risk of ASFV exposure to wild boar caused by foreign tourists. The overall mean annual probability of ASFV exposure to domestic pigs via PPAP carried by foreign job trainees was 0.169 [95% confidence interval (CI): 0.000-0.600], whereas that by foreign tourists was 0.050 [95% CI: 0.000-0.214], corresponding to approximately one introduction every 5.9 and 20 years, respectively. The risk of ASFV exposure to domestic pigs was dispersed over the country, whereas that of wild boar was generally higher in the western part of Japan, indicating that the characteristics of the potential ASF risk in each prefecture were varied.
• Quantitative risk assessment of African swine fever virus introduction to Japan via pork products brought in air passengers' luggage.

  Satoshi Ito, Cristina Jurado, José Manuel Sánchez-Vizcaíno, Norikazu Isoda

  Transboundary and emerging diseases 67 (2) 894 - 905 2020/03 

  The spread of African swine fever (ASF) has reached pandemic levels over the last decade, and outbreaks of this disease in China, Mongolia, Vietnam and Cambodia in 2018 and 2019 could accelerate its transmission to neighbouring Asian territories. Thus, the risk that the ASF virus (ASFV) will be introduced to disease-free territories increases each year. Since Japan is an island nation, the most likely way in which ASFV would be introduced is via pork products brought in air passengers' luggage (PPAP). Therefore, in the present study, we assessed the risk of ASFV introduction to Japan via PPAP. For the purposes of this analysis, we considered 214 international commercial flights travelling from 47 origin territories to 31 destination airports as potential routes of ASFV introduction via PPAP. The risk was estimated quantitatively through a stochastic model that considered the volume of air passengers' luggage, the amount of confiscated pork products that were carried in air passengers' luggage and the disease status of the origin territory. The overall mean annual probability of ASFV introduction to Japan via PPAP was found to be 0.941 [95% confidence interval (CI), 0.661-1.000], which approximately corresponds to one introduction every 1.06 years. At the origin territory level, Mongolia was led as the highest risk territory, with a risk of 0.864 (95% CI, 0.434-1.000), followed by China (0.697; 0.223-0.999), Vietnam (0.662; 0.196-0.998) and the Russian Federation (0.136; 0.018-0.401). At the destination airport level, Narita International Airport had the highest risk (0.905; 0.537-1.000), followed by Kansai International Airport (0.496; 0.109-0.961), Tokyo International Airport (0.389; 0.072-0.879) and Chubu Centrair International Airport (0.338; 0.058-0.816). This information will help improve risk management activities and monitoring systems to prevent the introduction of ASFV to Japan.
• Dynamics of Classical Swine Fever Spread in Wild Boar in 2018-2019, Japan.

  Norikazu Isoda, Kairi Baba, Satoshi Ito, Mitsugi Ito, Yoshihiro Sakoda, Kohei Makita

  Pathogens (Basel, Switzerland) 9 (2) 2020/02/13 [Refereed][Not invited]
   

  The prolongation of the classic swine fever (CSF) outbreak in Japan in 2018 was highly associated with the persistence and widespread of the CSF virus (CSFV) in the wild boar population. To investigate the dynamics of the CSF outbreak in wild boar, spatiotemporal analyses were performed. The positive rate of CSFV in wild boar fluctuated dramatically from March to June 2019, but finally stabilized at approximately 10%. The Euclidean distance from the initial CSF notified farm to the farthest infected wild boar of the day constantly increased over time since the initial outbreak except in the cases reported from Gunma and Saitama prefectures. The two-month-period prevalence, estimated using integrated nested Laplace approximation, reached >80% in half of the infected areas in March-April 2019. The area affected continued to expand despite the period prevalence decreasing up to October 2019. A large difference in the shapes of standard deviational ellipses and in the location of their centroids when including or excluding cases in Gunma and Saitama prefectures indicates that infections there were unlikely to have been caused simply by wild boar activities, and anthropogenic factors were likely involved. The emergence of concurrent space-time clusters in these areas after July 2019 indicated that CSF outbreaks were scattered by this point in time. The results of this epidemiological analysis help explain the dynamics of the spread of CSF and will aid in the implementation of control measures, including bait vaccination.
• Review on counter measures to coronavirus disease 2019 (COVID-19) pandemic, May 2020

  Taishi Kidaka, Sithumini M.W. Lokupathirage, Bungiriye Devinda Shameera Muthusinghe, Boniface Lombe Pongombo, Christida Estu Wastika, Zhouxing Wei, Shizuka Yoshioka, Mayumi Ishizuka, Yoshihiro Sakoda, Hiroaki Kariwa, Norikazu Isoda

  Japanese Journal of Veterinary Research 68 (3) 133 - 150 0047-1917 2020 

  An outbreak of novel coronavirus infection occurred in China at the end of 2019, which was designated as coronavirus disease 2019 (COVID-19), and spread to regions across Asia and ultimately all over the world. As of 21 May 2020, a total of more than 5 million cases with more than 350 thousand deaths were reported worldwide. Evaluation of the pathogenicity of the disease and determining the efficacy of control measures are essential for rapid containment of the disease. However, the world is facing difficulties in controlling COVID-19 at both of the national and global levels due to variations in pathogenicity of infection by severe acute respiratory syndrome coronavirus 2, the causal agent of COVID-19, and to diverse measures applied in each country based on their control capacities and policies. In the present review, we summarize the basic information and findings related to the COVID-19 pandemic, including pathogen agent, epidemiology, disease transmission, and clinical manifestations. Diagnosis, treatment, and preventive measures applied or under development all over the world are also reviewed to provide the opportunity to establish a more effective scenario for disease containment. Humanity has progressed by developing countless great technologies and immense scientific theories, however it may be a fact that we cannot conquer all risks to humanity. New findings and challenges for the unprecedented pandemic at the global level, such as COVID-19, should also contribute to preparedness for unknown diseases in future, similar to the lessons learnt from severe acute respiratory syndrome and the pandemic A(H1N1)pdm09 influenza.
• Role of Wild Boar in the Spread of Classical Swine Fever in Japan.

  Satoshi Ito, Cristina Jurado, Jaime Bosch, Mitsugi Ito, José Manuel Sánchez-Vizcaíno, Norikazu Isoda, And Yoshihiro Sakoda

  Pathogens (Basel, Switzerland) 8 (4) 2019/10/24 [Refereed][Not invited]
   

  Since September 2018, nearly 900 notifications of classical swine fever (CSF) have been reported in Gifu Prefecture (Japan) affecting domestic pig and wild boar by the end of August 2019. To determine the epidemiological characteristics of its spread, a spatio-temporal analysis was performed using actual field data on the current epidemic. The spatial study, based on standard deviational ellipses of official CSF notifications, showed that the disease likely spread to the northeast part of the prefecture. A maximum significant spatial association estimated between CSF notifications was 23 km by the multi-distance spatial cluster analysis. A space-time permutation analysis identified two significant clusters with an approximate radius of 12 and 20 km and 124 and 98 days of duration, respectively. When the area of the identified clusters was overlaid on a map of habitat quality, approximately 82% and 75% of CSF notifications, respectively, were found in areas with potential contact between pigs and wild boar. The obtained results provide information on the current CSF epidemic, which is mainly driven by wild boar cases with sporadic outbreaks on domestic pig farms. These findings will help implement control measures in Gifu Prefecture.
• Slaughterhouse survey for detection of bovine viral diarrhea infection among beef cattle in Kyushu, Japan.

  Mohammad Aref Agah, Kosuke Notsu, Heba M El-Khaiat, Genki Arikawa, Meiko Kubo, Shuya Mitoma, Tamaki Okabayashi, Hirohisa Mekata, Eslam Elhanafy, Hala El Daous, Thi Ngan Mai, Thi Huyen Nguyen, Norikazu Isoda, Yoshihiro Sakoda, Junzo Norimine, Satoshi Sekiguchi

  The Journal of veterinary medical science 81 (10) 1450 - 1454 0916-7250 2019/10/18 [Refereed][Not invited]
   

  Bovine viral diarrhea virus (BVDV) footprint has spread across the globe and is responsible for one of the most economically important diseases in cattle. In Japan, some regional surveillance and preventive measures to control bovine viral diarrhea (BVD) have been implemented. However, BVDV infection is poorly understood in cattle industries, and there is no systematic BVD surveillance system and control program. Kyushu is the center for raising beef cattle in Japan. Therefore, this study aimed to determine the BVDV infection using a slaughterhouse survey among beef cattle in Kyushu, Japan. A total of 1,075 blood samples were collected at two regional slaughterhouses in Miyazaki prefecture from December 2015 to June 2016. Antigen ELISA was used for detection of BVDV antigen in blood samples. Two samples showed positive results (2/1,075; 0.18%). BVDV RNA was extracted from positive blood samples; the sequence was determined and analyzed by the neighbor-joining method for construction of the phylogenetic tree. Phylogenetic analysis based on the 5'-UTR revealed that the two positive samples were grouped into the same subtype BVDV-1b in the BVDV-1 genotype, but the infected cattle belonged to two different farms. In conclusion, this is the first study to identify the presence of BVDV in a slaughterhouse survey in Kyushu. These findings suggest that a slaughterhouse survey is a useful tool for developing a surveillance system for monitoring infectious diseases in cattle.
• Complete Genome Sequence of Rickettsia asiatica Strain Maytaro1284, a Member of Spotted Fever Group Rickettsiae Isolated from an Ixodes ovatus Tick in Japan.

  Thu MJ, Qiu Y, Yamagishi J, Kusakisako K, Ogata S, Moustafa MAM, Isoda N, Sugimoto C, Katakura K, Nonaka N, Nakao R

  Microbiology resource announcements 8 (37) 2019/09 [Refereed][Not invited]
   

  This is the first report of the complete genome sequence of Rickettsia asiatica strain Maytaro1284, isolated from an Ixodes ovatus tick in Japan. The genome contains a 1,344,324-bp circular chromosome and one plasmid of 74,761 bp. There was no outer membrane protein A (ompA) gene encoded in the genome.
• A Novel Combination of Prion Strain Co-Occurrence in Patients with Sporadic Creutzfeldt-Jakob Disease.

  Atsushi Kobayashi, Yasushi Iwasaki, Masaki Takao, Yuko Saito, Toru Iwaki, Zechen Qi, Ryouta Torimoto, Taishi Shimazaki, Yoshiko Munesue, Norikazu Isoda, Hirofumi Sawa, Keisuke Aoshima, Takashi Kimura, Hinako Kondo, Shirou Mohri, Tetsuyuki Kitamoto

  The American journal of pathology 189 (6) 1276 - 1283 2019/06 

  Six subgroups of sporadic Creutzfeldt-Jakob disease have been identified by distinctive clinicopathologic features, genotype at polymorphic codon 129 [methionine (M)/valine (V)] of the PRNP gene, and type of abnormal prion proteins (type 1 or 2). In addition to the pure subgroups, mixed neuropathologic features and the coexistence of two types of abnormal prion proteins in the same patient also have been reported. Here, we found that a portion of the patients previously diagnosed as MM1 had neuropathologic characteristics of the MM2 thalamic form (ie, neuronal loss of the inferior olivary nucleus of the medulla). Furthermore, coexistence of biochemical features of the MM2 thalamic form also was confirmed in the identified cases. In addition, in transmission experiments using prion protein-humanized mice, the brain material from the identified case showed weak infectivity and generated characteristic abnormal prion proteins in the inoculated mice resembling those after inoculation with brain material of MM2 thalamic form. Taken together, these results show that the co-occurrence of MM1 and MM2 thalamic form is a novel entity of sporadic Creutzfeldt-Jakob disease prion strain co-occurrence. The present study raises the possibility that the co-occurrence of the MM2 thalamic form might have been overlooked so far because of the scarcity of abnormal prion protein accumulation and restricted neuropathology.
• Spatiotemporal and risk analysis of H5 highly pathogenic avian influenza in Vietnam, 2014-2017.

  Lam Thanh Nguyen, Mark A Stevenson, Simon M Firestone, Leslie D Sims, Duc Huy Chu, Long Van Nguyen, Tien Ngoc Nguyen, Kien Trung Le, Norikazu Isoda, Keita Matsuno, Masatoshi Okamatsu, Hiroshi Kida, Yoshihiro Sakoda

  Preventive veterinary medicine 178 104678 - 104678 2019/04/22 [Refereed][Not invited]
   

  The aim of this study was to describe the spatiotemporal distribution of H5 HPAI outbreak reports for the period 2014-2017 and to identify factors associated with H5 HPAI outbreak reports. Throughout the study period, a total of 139 outbreaks of H5 HPAI in poultry were reported, due to either H5N1 (96 outbreaks) or H5N6 (43 outbreaks) subtype viruses. H5N1 HPAI outbreaks occurred in all areas of Vietnam while H5N6 HPAI outbreaks were only reported in the northern and central provinces. We counted the number of H5N1 and H5N6 outbreak report-positive districts per province over the four-year study period and calculated the provincial-level standardized morbidity ratio for H5N1 and H5N6 outbreak reports as the observed number of positive districts divided by the expected number. A mixed-effects, zero-inflated Poisson regression model was developed to identify risk factors for outbreak reports of each H5N1 and H5N6 subtype virus. Spatially correlated and uncorrelated random effects terms were included in this model to identify areas of the country where outbreak reports occurred after known risk factors had been accounted-for. The presence of an outbreak report in a province in the previous 6-12 months increased the provincial level H5N1 outbreak report risk by a factor of 2.42 (95% Bayesian credible interval [CrI] 1.27-4.60) while 1000 bird increases in the density of chickens decreased provincial level H5N6 outbreak report risk by a factor of 0.65 (95% CrI 0.38 to 0.97). We document distinctly different patterns in the spatial and temporal distribution of H5N1 and H5N6 outbreak reports. Most of the variation in H5N1 report risk was accounted-for by the fixed effects included in the zero-inflated Poisson model. In contrast, the amount of unaccounted-for risk in the H5N6 model was substantially greater than the H5N1 model. For H5N6 we recommend that targeted investigations should be carried out in provinces with relatively large spatially correlated random effect terms to identify likely determinants of disease. Similarly, investigations should be carried out in provinces with relatively low spatially correlated random effect terms to identify protective factors for disease and/or reasons for failure to report.
• Assessment of the cost effectiveness of compulsory testing of introduced animals and bulk tank milk testing for bovine viral diarrhea in Japan.

  Norikazu Isoda, Akihiro Asano, Michiru Ichijo, Hiroshi Ohno, Kazuhiko Sato, Hirokazu Okamoto, Shigeru Nakao, Hajime Kato, Kazuma Saito, Naoki Ito, Akira Usui, Hiroaki Takayama, Yoshihiro Sakoda

  The Journal of veterinary medical science 81 (4) 577 - 585 0916-7250 2019/04/16 [Refereed][Not invited]
   

  Bovine viral diarrhea (BVD) is a chronic disease of cattle caused by infection with BVD virus (BVDV) and can result in economic losses within the livestock industry. In Japan, the test and culling policy is a basic control measure, and implementation of an adequate vaccination program is recommended as a national policy. In addition, optional control measures, including compulsory testing of introduced animals and bulk tank milk (BTM) testing as a mass screening method, are used in several provinces, but their efficacy has not been completely assessed. We evaluated these control measures using the scenario tree model of BVD in Japan, developed in the previous study. The model outputs indicated that compulsory testing of all introduced cattle, rather than only heifers and/or non-vaccinated cattle, was cost effective and reduced the risk of BVDV introduction due to animal movement and that BTM testing could effectively monitor most part of the cattle population. Vaccination coverage and BVDV prevalence among introduced cattle could also affect the cost effectiveness of compulsory testing of targeted cattle, particularly under low vaccination coverage or high BVDV prevalence. However, even with the implementation of a highly effective monitoring scheme for many years, BVD risk could not be eliminated; it instead converged at a very low level (0.02%). Disease models with a cost-effective output could be a powerful tool in developing a control scheme for chronic animal diseases, including BVD, with the consent of relevant stakeholders.
• Genetic diversity of Mycobacterium tuberculosis Central Asian Strain isolates from Nepal and comparison with neighboring countries.

  Yogendra Shah, Ajay Poudel, Bhagwan Maharjan, Jeewan Thapa, Tomoyuki Yamaguchi, Hassan Mahmoud Diab, Basu Dev Pandey, Eddie Solo, Norikazu Isoda, Yasuhiko Suzuki, Chie Nakajima

  Transactions of the Royal Society of Tropical Medicine and Hygiene 113 (4) 203 - 211 2019/04/01 

  BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) is an emerging threat for successful tuberculosis control worldwide. Central Asian Strain (CAS) has been reported as one of the dominant families contributing to MDR-TB in South Asia including Nepal, India and Pakistan. The aim of this study was to better understand the genetic characteristics of MDR-TB CAS family isolates circulating in Nepal and compare the results with neighboring countries. METHODS: A total of 145 MDR-TB CAS family isolates collected in Nepal from 2008 to 2013 were analyzed by spoligotyping and mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) analysis. In addition, we compared these data with published data from India and Pakistan to investigate a possible epidemiological link via construction of a minimum spanning tree (MST). RESULTS: Spoligotyping analysis exhibited CAS1_Delhi SIT26 (n=60) as the predominant lineage among the MDR-TB CAS family in all three countries. However, the combined analysis with spoligotyping and MIRU-VNTR further discriminated 60 isolates into 49 different types and 5 clusters. Each cluster was composed of 14 isolates with a clustering rate of 23.3%, suggesting ongoing transmissions. Based on MST data from neighboring countries, we elucidated an evolutionary relationship between the two countries, Nepal and India, which could be explained by their open border. CONCLUSION: This study identified the evolutionary relationships among MDR-TB CAS1_Delhi subfamily isolates from Nepal and those from neighboring countries.
• Ganglioside Synthase Knockout Reduces Prion Disease Incubation Time in Mouse Models.

  Atsushi Kobayashi, Zechen Qi, Taishi Shimazaki, Yoshiko Munesue, Tomomi Miyamoto, Norikazu Isoda, Hirofumi Sawa, Keisuke Aoshima, Takashi Kimura, Shirou Mohri, Tetsuyuki Kitamoto, Tadashi Yamashita, Ichiro Miyoshi

  The American journal of pathology 189 (3) 677 - 686 2019/03 

  Localization of the abnormal and normal isoforms of prion proteins to detergent-resistant membrane microdomains, lipid rafts, is important for the conformational conversion. Lipid rafts are enriched in sialic acid-containing glycosphingolipids (namely, gangliosides). Alteration in the ganglioside composition of lipid rafts can affect the localization of lipid raft-associated proteins. To investigate the role of gangliosides in the pathogenesis of prion diseases, we performed intracerebral transmission study of a scrapie prion strain Chandler and a Gerstmann-Sträussler-Scheinker syndrome prion strain Fukuoka-1 using various knockout mouse strains ablated with ganglioside synthase gene (ie, GD2/GM2 synthase, GD3 synthase, or GM3 synthase). After challenge with the Chandler strain, GD2/GM2 synthase knockout mice showed 20% reduction of incubation time, reduced prion protein deposition in the brain with attenuated glial reactions, and reduced localization of prion proteins to lipid rafts. These results raise the possibility that the gangliosides may have an important role in prion disease pathogenesis by affecting the localization of prion proteins to lipid rafts.
• Diversity of spotted fever group rickettsiae and their association with host ticks in Japan.

  May June Thu, Yongjin Qiu, Keita Matsuno, Masahiro Kajihara, Akina Mori-Kajihara, Ryosuke Omori, Naota Monma, Kazuki Chiba, Junji Seto, Mutsuyo Gokuden, Masako Andoh, Hideo Oosako, Ken Katakura, Ayato Takada, Chihiro Sugimoto, Norikazu Isoda, Ryo Nakao

  Scientific reports 9 (1) 1500 - 1500 2019/02/06 [Refereed][Not invited]
   

  Spotted fever group (SFG) rickettsiae are obligate intracellular Gram-negative bacteria mainly associated with ticks. In Japan, several hundred cases of Japanese spotted fever, caused by Rickettsia japonica, are reported annually. Other Rickettsia species are also known to exist in ixodid ticks; however, their phylogenetic position and pathogenic potential are poorly understood. We conducted a nationwide cross-sectional survey on questing ticks to understand the overall diversity of SFG rickettsiae in Japan. Out of 2,189 individuals (19 tick species in 4 genera), 373 (17.0%) samples were positive for Rickettsia spp. as ascertained by real-time PCR amplification of the citrate synthase gene (gltA). Conventional PCR and sequencing analyses of gltA indicated the presence of 15 different genotypes of SFG rickettsiae. Based on the analysis of five additional genes, we characterised five Rickettsia species; R. asiatica, R. helvetica, R. monacensis (formerly reported as Rickettsia sp. In56 in Japan), R. tamurae, and Candidatus R. tarasevichiae and several unclassified SFG rickettsiae. We also found a strong association between rickettsial genotypes and their host tick species, while there was little association between rickettsial genotypes and their geographical origins. These observations suggested that most of the SFG rickettsiae have a limited host range and are maintained in certain tick species in the natural environment.
• Isolation of Rickettsia, Rickettsiella, and Spiroplasma from Questing Ticks in Japan Using Arthropod Cells.

  Thu MJ, Qiu Y, Kataoka-Nakamura C, Sugimoto C, Katakura K, Isoda N, Nakao R

  Vector borne and zoonotic diseases (Larchmont, N.Y.) 19 (7) 474 - 485 1530-3667 2019/02 [Refereed][Not invited]
   

  Ticks are blood-sucking ectoparasites that transmit zoonotic pathogens to humans and animals. Ticks harbor not only pathogenic microorganisms but also endosymbionts. Although some tick endosymbionts are known to be essential for the survival of ticks, their roles in ticks remain poorly understood. The main aim of this study was to isolate and characterize tick-borne microorganisms from field-collected ticks using two arthropod cell lines derived from Ixodes scapularis embryos (ISE6) and Aedes albopictus larvae (C6/36). A total of 170 tick homogenates originating from 15 different tick species collected in Japan were inoculated into each cell line. Bacterial growth was confirmed by PCR amplification of 16S ribosomal DNA (rDNA) of eubacteria. During the 8-week observation period, bacterial isolation was confirmed in 14 and 4 samples using ISE6 and C6/36 cells, respectively. The sequencing analysis of the 16S rDNA PCR products indicated that they were previously known tick-borne pathogens/endosymbionts in three different genera: Rickettsia, Rickettsiella, and Spiroplasma. These included four previously validated rickettsial species namely Rickettsia asiatica (n = 2), Rickettsia helvetica (n = 3), Rickettsia monacensis (n = 2), and Rickettsia tamurae (n = 3) and one uncharacterized genotype Rickettsia sp. LON (n = 2). Four isolates of Spiroplasma had the highest similarity with previously reported Spiroplasma isolates: Spiroplasma ixodetis obtained from ticks in North America and Spiroplasma sp. Bratislava 1 obtained from Ixodes ricinus in Europe, while two isolates of Rickettsiella showed 100% identity with Rickettsiella sp. detected from Ixodes uriae at Grimsey Island in Iceland. To the best of our knowledge, this is the first report on successful isolation of Rickettsiella from ticks. The isolates obtained in this study can be further analyzed to evaluate their pathogenic potential in animals and their roles as symbionts in ticks.
• Genetic diversity and distribution dynamics of multidrug-resistant Mycobacterium tuberculosis isolates in Nepal.

  Bhagwan Maharjan, Chie Nakajima, Norikazu Isoda, Jeewan Thapa, Ajay Poudel, Yogendra Shah, Tomoyuki Yamaguchi, Bhabana Shrestha, Harald Hoffmann, Korkut Avsar, Ashish Shrestha, Stephen V Gordon, Yasuhiko Suzuki

  Scientific reports 8 (1) 16634 - 16634 2018/11/09 

  Multidrug-resistant tuberculosis (MDR-TB) is an emerging public health problem in Nepal. Despite the implementation of a successful TB control program in Nepal, notifications of MDR-TB are increasing, yet the reasons are unknown. The objective of this study was to understand the genetic diversity and epidemiological characteristics of MDR-Mycobacterium tuberculosis (MTB) isolates in Nepal. We isolated and genotyped 498 MDR-MTB isolates collected from April 2009 to March 2013 and analyzed the patients' background information. Our results showed that the lineage 2 (Beijing family) was the most predominant lineage (n = 241; 48.4%), followed by lineage 3 (n = 153, 30.7%). Lineage 4 was the third most prevalent (n = 73, 14.5%) followed by lineage 1 (n = 32, 6.4%). The lineages were significantly associated with geographic region, ethnic group, age and sex of patients. The Beijing genotype was found to have an important role in transmitting MDR-TB in Nepal and was significantly associated with the eastern region, mongoloid ethnic group and younger age group. We conclude that early diagnosis and treatment including molecular-epidemiological surveillance of MDR-TB cases will help to control transmission of MDR-TB in Nepal.
• Development of a quick bioassay for the evaluation of transmission properties of acquired prion diseases

  Munesue Y, Shimazaki T, Qi Z, Isoda N, Sawa H, Aoshima K, Kimura T, Mohri S, Kitamoto T, Kobayashi A

  Neurosci Lett 668 43 - 47 0304-3940 2018/03 [Refereed][Not invited]
  
• Prevalence of hobi-like viruses in Japan between 2012 and 2017 based on virological methods and serology

  Takashi Kozasa, Shiho Torii, Ken Ichiro Kameyama, Makoto Nagai, Norikazu Isoda, Mai Shiokawa, Hiroshi Aoki, Masatoshi Okamatsu, Hideto Sekiguchi, Akito Saito, Yoshihiro Sakoda

  Japanese Journal of Veterinary Research 66 (4) 317 - 324 0047-1917 2018 

  The purpose of this study was to investigate the prevalence of HoBi-like viruses in Japan and evaluate the immune response induced by bovine viral diarrhea virus (BVDV) vaccines available in Japan. No HoBi-like viruses were detected by RT-PCR and virus isolation in cattle sera collected in Japan between 2012 and 2017. Nevertheless, neutralizing antibody titers against HoBi-like viruses ranged from < 2 to 4,096, demonstrating cross-reactivity to HoBi-like viruses in cattle infected (naturally or vaccinated) with BVDV-1 and BVDV-2. These results suggest that continuous vaccination with both BVDV-1 and BVDV-2 contributes to the control of HoBi-like viruses in Japan.
• A cross-sectional study to quantify the prevalence of avian influenza viruses in poultry at intervention and non-intervention live bird markets in central Vietnam, 2014

  D. -H. Chu, M. A. Stevenson, L. V. Nguyen, N. Isoda, S. M. Firestone, T. N. Nguyen, L. T. Nguyen, K. Matsuno, M. Okamatsu, H. Kida, Y. Sakoda

  TRANSBOUNDARY AND EMERGING DISEASES 64 (6) 1991 - 1999 1865-1674 2017/12 [Refereed][Not invited]
   

  In Vietnam, live bird markets are found in most populated centres, providing the means by which fresh poultry can be purchased by consumers for immediate consumption. Live bird markets are aggregation points for large numbers of poultry, and therefore, it is common for a range of avian influenza viruses to be mixed within live bird markets as a result of different poultry types and species being brought together from different geographical locations. We conducted a cross-sectional study in seven live bird markets in four districts of Thua Thien Hue Province in August and December, 2014. The aims of this study were to (i) document the prevalence of avian influenza in live bird markets (as measured by virus isolation); and (ii) quantify individual bird-, seller- and market-level characteristics that rendered poultry more likely to be positive for avian influenza virus at the time of sale. A questionnaire soliciting details of knowledge, attitude and avian influenza practices was administered to poultry sellers in study markets. At the same time, swabs and faecal samples were collected from individual poultry and submitted for isolation of avian influenza virus. The final data set comprised samples from 1,629 birds from 83 sellers in the seven live bird markets. A total of 113 birds were positive for virus isolation; a prevalence of 6.9 (95% CI 5.8-8.3) avian influenza virus-positive birds per 100 birds submitted for sale. After adjusting for clustering at the market and individual seller levels, none of the explanatory variables solicited in the questionnaire were significantly associated with avian influenza virus isolation positivity. The proportions of variance at the individual market, seller and individual bird levels were 6%, 48% and 46%, respectively. We conclude that the emphasis of avian influenza control efforts in Vietnam should be at the individual seller level as opposed to the market level.
• High diversity of multidrug-resistant Mycobacterium tuberculosis Central Asian Strain isolates in Nepal

  Yogendra Shah, Bhagwan Maharjan, Jeewan Thapa, Ajay Poudel, Hassan Mahmoud Diab, Basu Dev Pandey, Eddie S. Solo, Norikazu Isoda, Yasuhiko Suzuki, Chie Nakajima

  INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES 63 13 - 20 1201-9712 2017/10 [Refereed][Not invited]
   

  Objectives: Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) poses a major public health problem in Nepal. Although it has been reported as one of the dominant genotypes of MTB in Nepal, little information on the Central Asian Strain (CAS) family is available, especially isolates related to multidrug resistance (MDR) cases. This study aimed to elucidate the genetic and epidemiological characteristics of MDR CAS isolates in Nepal. Methods: A total of 145 MDR CAS isolates collected in Nepal from 2008 to 2013 were characterized by spoligotyping, mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) analysis, and drug resistance-associated gene sequencing. Results: Spoligotyping analysis showed CAS1_Delhi SIT26 as predominant (60/145, 41.4%). However, by combining spoligotyping and MIRU-VNTR typing, it was possible to successfully discriminate all 145 isolates into 116 different types including 18 clusters with 47 isolates (clustering rate 32.4%). About a half of these clustered isolates shared the same genetic and geographical characteristics with other isolates in each cluster, and some of them shared rare point mutations in rpoB that are thought to be associated with rifampicin resistance. Conclusions: Although the data obtained show little evidence that large outbreaks of MDR-TB caused by the CAS family have occurred in Nepal, they strongly suggest several MDR-MTB transmission cases. (C) 2017 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.
• Oxidative stress and respiratory symptoms due to human exposure to polycyclic aromatic hydrocarbons (PAHs) in Kumasi, Ghana.

  Nesta Bortey-Sam, Yoshinori Ikenaka, Osei Akoto, Shouta M M Nakayama, Kwadwo A Asante, Elvis Baidoo, Christian Obirikorang, Aksorn Saengtienchai, Norikazu Isoda, Collins Nimako, Hazuki Mizukawa, Mayumi Ishizuka

  Environmental pollution (Barking, Essex : 1987) 228 311 - 320 2017/09 

  Studies of polycyclic aromatic hydrocarbons (PAHs) and its metabolites in PM10, soils, rat livers and cattle urine in Kumasi, Ghana, revealed high concentrations and cancer potency. In addition, WHO and IARC have reported an increase in cancer incidence and respiratory diseases in Ghana. Human urine were therefore collected from urban and control sites to: assess the health effects associated with PAHs exposure using malondialdehyde (MDA) and 8-hydroxy-2-deoxyguanosine (8-OHdG); identify any association between OH-PAHs, MDA, 8-OHdG with age and sex; and determine the relationship between PAHs exposure and occurrence of respiratory diseases. From the results, urinary concentrations of the sum of OH-PAHs (∑OHPAHs) were significantly higher from urban sites compared to the control site. Geometric mean concentrations adjusted by specific gravity, GMSG, indicated 2-OHNaphthalene (2-OHNap) (6.01 ± 4.21 ng/mL) as the most abundant OH-PAH, and exposure could be through the use of naphthalene-containing-mothballs in drinking water purification, insect repellent, freshener in clothes and/or "treatment of various ailments". The study revealed that exposure to naphthalene significantly increases the occurrence of persistent cough (OR = 2.68, CI: 1.43-5.05), persistent headache (OR = 1.82, CI: 1.02-3.26), tachycardia (OR = 3.36, CI: 1.39-8.10) and dyspnea (OR = 3.07, CI: 1.27-7.43) in Kumasi residents. Highest level of urinary 2-OHNap (224 ng/mL) was detected in a female, who reported symptoms of persistent cough, headache, tachycardia, nasal congestion and inflammation, all of which are symptoms of naphthalene exposure according to USEPA. The ∑OHPAHs, 2-OHNap, 2-3-OHFluorenes, and -OHPhenanthrenes showed a significantly positive correlation with MDA and 4-OHPhenanthrene with 8-OHdG, indicating possible lipid peroxidation/cell damage or degenerative disease in some participants. MDA and 8-OHdG were highest in age group 21-60. The present study showed a significant sex difference with higher levels of urinary OH-PAHs in females than males.
• Evaluation of bovine viral diarrhea virus control strategies in dairy herds in Hokkaido, Japan using stochastic modelling

  Satoshi Sekiguchi, Patrick Presi, Ryosuke Omori, Katharina Stärk, Manon Schuppers, Norikazu Isoda, Yasuhiro Yoshikawa, Takashi Umemura, Hiroyuki Nakayama, Yoshinori Fujii, Yoshihiro Sakoda

  Transboundary and Emerging Diseases 65 (1) 135 - 144 2017/08 [Refereed][Not invited]
  
• Evaluation of control measures for bovine viral diarrhea implemented in Nemuro District, Hokkaido, Japan, using a scenario tree model

  Norikazu Isoda, Akihiro Asano, Michiru Ichijo, Shiho Wakamori, Hiroshi Ohno, Kazuhiko Sato, Hirokazu Okamoto, Shigeru Nakao, Hajime Kato, Kazuma Saito, Naoki Ito, Akira Usui, Hiroaki Takayama, Yoshihiro Sakoda

  JOURNAL OF VETERINARY MEDICAL SCIENCE 79 (7) 1172 - 1181 0916-7250 2017/07 [Refereed][Not invited]
   

  A scenario tree model was developed to propose efficient bovine viral diarrhea (BVD) control measures. The model used field data in eastern Hokkaido where the risk of BVDV infection in cattle has been reduced by an eradication program including mass vaccination, individual tests prior to communal pasture grazing, herd screening tests using bulk milk, and outbreak investigations of newly infected herds. These four activities were then used as hypothesized control measures in the simulation. In each simulation, the numbers of cattle infected persistently and transiently with BVDV detected by clinical manifestations and diagnosis tests and of missed by all of the diagnosis tests were calculated, and the numbers were used as indicators to be compared for the efficacy of the control measures. The model outputs indicated that the adoption of mass vaccination decreased the number of missed BVD cattle, although it did not increase the number of detected BVD cattle. Under implementation of mass vaccination, the efficacy of individual tests on selected 20% of the young and adult cattle was equal to that of the herd screening test performed in all the herds. When the virus prevalence or the number of sensitive animals becomes low, the efficacy of herd screening test was superior to one of individual tests. Considering the model outputs together, the scenario tree model developed in the present study was useful to compare the efficacy of the control measures for BVD.
• Therapeutic efficacy of peramivir against H5N1 highly pathogenic avian influenza viruses harboring the neuraminidase H275Y mutation

  Masanori Kobayashi, Makoto Kodama, Takeshi Noshi, Ryu Yoshida, Takushi Kanazu, Naoki Nomura, Kosuke Soda, Norikazu Isoda, Masatoshi Okamatsu, Yoshihiro Sakoda, Yoshinori Yamano, Akihiko Sato, Hiroshi Kida

  ANTIVIRAL RESEARCH 139 41 - 48 0166-3542 2017/03 [Refereed][Not invited]
   

  High morbidity and mortality associated with human cases of highly pathogenic avian influenza (HPAI) viruses, including H5N1 influenza virus, have been reported. The purpose of the present study was to evaluate the antiviral effects of peramivir against HPAI viruses. In neuraminidase (NA) inhibition and virus replication inhibition assays, peramivir showed strong inhibitory activity against H5N1, H7N1 and H7N7 HPAI viruses with sub-nanomolar activity in enzyme assays. In H5N1 viruses containing the NA H275Y mutation, the antiviral activity of peramivir against the variant was lower than that against the wild-type. Evaluation of the in vivo antiviral activity showed that a single intravenous treatment of peramivir (10 mg/kg) prevented lethality in mice infected with wild-type H5N1 virus and also following infection with H5N1 virus with the H275Y mutation after a 5 day administration of peramivir (30 mg/kg). Furthermore, mice injected with peramivir showed low viral titers and low levels of proinflammatory cytokines in the lungs. These results suggest that peramivir has therapeutic activity against HPAI viruses even if the virus harbors the NA H275Y mutation. (C) 2016 Elsevier B.V. All rights reserved.
• Molecular epidemiology of pathogenic Leptospira spp. among large ruminants in the Philippines

  Marvin A. Villanueva, Claro N. Mingala, Michelle M. Balbin, Chie Nakajima, Norikazu Isoda, Yasuhiko Suzuki, Nobuo Koizumi

  JOURNAL OF VETERINARY MEDICAL SCIENCE 78 (11) 1649 - 1655 0916-7250 2016/11 [Refereed][Not invited]
   

  The extent of Leptospira infection in large ruminants resulting to economic problems in livestock industry in a leptospirosis-endemic country like the Philippines has not been extensively explored. Therefore, we determined the prevalence and carrier status of leptospirosis in large ruminants using molecular techniques and assessed the risk factors of acquiring leptospirosis in these animals. Water buffalo and cattle urine samples (n=831) collected from 21 farms during 2013-2015 were subjected to flaB-nested PCR to detect pathogenic Leptospira spp. Leptospiral flaB was detected in both species with a detection rate of 16.1%. Leptospiral DNA was detected only in samples from animals managed in communal farms. Sequence analysis of Leptospira flaB in large ruminants revealed the formation of three major clusters with L. borgpetersenii or L. kirschneri. One farm contained Leptospira flaB sequences from all clusters identified in this study, suggesting this farm was the main source of leptospires for other farms. This study suggested that these large ruminants are infected with various pathogenic Leptospira species causing possible major economic loss in the livestock industry as well as potential Leptospira reservoirs that can transmit infection to humans and other animals in the Philippines.
• Serological investigation of Leptospira infection and its circulation in one intensive-type water buffalo farm in the Philippines

  Marvin A. Villanueva, Claro N. Mingala, Nina G. Gloriani, Yasutake Yanagihara, Norikazu Isoda, Chie Nakajima, Yasuhiko Suzuki, Nobuo Koizumi

  JAPANESE JOURNAL OF VETERINARY RESEARCH 64 (1) 15 - 24 0047-1917 2016/02 [Refereed][Not invited]
   

  Water buffalo is an indispensable livestock in the Philippines. Leptospirosis is a serious zoonosis that can be fatal to humans and cause reproductive problems in livestock. Leptospirosis has been reported in some countries where water buffaloes are commercially raised, highlighting the Leptospira prevalence in this farming system, but information on leptospirosis in water buffalo farms in the Philippines is limited. In this study, we collected blood samples from rats (n = 21), and water buffaloes (n = 170) from different groups and locations in one intensive-type buffalo farm in the Philippines. Serum was analyzed by microscopic agglutination test (MAT). Anti-Leptospira antibodies reacting with serogroups Canicola, Icterohaemorrhagiae and Pomona were found in sera of 30% tested rats, and 48% of water buffalo sera tested positive for at least one Leptospira strain, in which serogroups Mini, Hebdomadis, Tarassovi and Pyrogenes were predominantly agglutinated. The number of seropositive young water buffaloes (<1 year-old) was lower than that of older seropositive ones. Furthermore, sera from younger water buffaloes were reactive with single serotypes with low MAT titers, but older animals were reactive with multiple Leptospira strains with variable MAT titers. In addition, antibodies against serogroups Icterohaemorrhagiae and Pomona were detected in both animals. Finally, Leptospira infection was found associated with age and animal grouping, highlighting the impact of management in the persistence of leptospirosis at intensive-type buffalo farm settings in the Philippines. Further investigation and appropriate control strategies are required to prevent leptospirosis from causing risks to public health and economic losses to the water buffalo farming industry.
• Differential potential for envelope glycoprotein-mediated steric shielding of host cell surface proteins among filoviruses

  Osamu Noyori, Keita Matsuno, Masahiro Kajihara, Eri Nakayama, Manabu Igarashi, Makoto Kuroda, Norikazu Isoda, Reiko Yoshida, Ayato Takada

  VIROLOGY 446 (1-2) 152 - 161 0042-6822 2013/11 [Refereed][Not invited]
   

  The viral envelope glycoprotein (GP) is thought to play important roles in the pathogenesis of filovirus infection. It is known that GP expressed on the cell surface forms a steric shield over host proteins such as major histocompatibility complex class I and integrin pi, which may result in the disorder of cell-to-cell contacts and/or inhibition of the immune response. However, it is not clarified whether this phenomenon contributes to the pathogenicity of filoviruses. In this study, we found that the steric shielding efficiency differed among filovirus strains and was correlated with the difference in their relative pathogenicities. While the highly glycosylated mucin-like region of GP was indispensable, the differential shielding efficiency did not necessarily depend on the primary structure of the mucin-like region, suggesting the importance of the overall properties (e.g., flexibility and stability) of the GP molecule for efficient shielding of host proteins. (C) 2013 Elsevier Inc. All rights reserved.
• Excessive Cytokine Response to Rapid Proliferation of Highly Pathogenic Avian Influenza Viruses Leads to Fatal Systemic Capillary Leakage in Chickens

  Saya Kuribayashi, Yoshihiro Sakoda, Takeshi Kawasaki, Tomohisa Tanaka, Naoki Yamamoto, Masatoshi Okamatsu, Norikazu Isoda, Yoshimi Tsuda, Yuji Sunden, Takashi Umemura, Noriko Nakajima, Hideki Hasegawa, Hiroshi Kida

  PLOS ONE 8 (7) e68375  1932-6203 2013/07 [Refereed][Not invited]
   

  Highly pathogenic avian influenza viruses (HPAIVs) cause lethal infection in chickens. Severe cases of HPAIV infections have been also reported in mammals, including humans. In both mammals and birds, the relationship between host cytokine response to the infection with HPAIVs and lethal outcome has not been well understood. In the present study, the highly pathogenic avian influenza viruses A/turkey/Italy/4580/1999 (H7N1) (Ty/Italy) and A/chicken/Netherlands/2586/2003 (H7N7) (Ck/NL) and the low pathogenic avian influenza virus (LPAIV) A/chicken/Ibaraki/1/2005 (H5N2) (Ck/Ibaraki) were intranasally inoculated into chickens. Ty/Italy replicated more extensively than Ck/NL in systemic tissues of the chickens, especially in the brain, and induced excessive mRNA expression of inflammatory and antiviral cytokines (IFN-gamma, IL-1 beta, IL-6, and IFN-alpha) in proportion to its proliferation. Using in situ hybridization, IL-6 mRNA was detected mainly in microglial nodules in the brain of the chickens infected with Ty/Italy. Capillary leakage assessed by Evans blue staining was observed in multiple organs, especially in the brains of the chickens infected with Ty/Italy, and was not observed in those infected with Ck/NL. In contrast, LPAIV caused only local infection in the chickens, with neither apparent cytokine expression nor capillary leakage in any tissue of the chickens. The present results indicate that an excessive cytokine response is induced by rapid and extensive proliferation of HPAIV and causes fatal multiple organ failure in chickens.
• The nucleoprotein is responsible for intracerebral pathogenicity of A/duck/Mongolia/47/2001 (H7N1) in chicks

  Norikazu Isoda, Yoshimi Tsuda, Shingo Asakura, Masatoshi Okamatsu, Yoshihiro Sakoda, Hiroshi Kida

  ARCHIVES OF VIROLOGY 157 (12) 2257 - 2264 0304-8608 2012/12 [Refereed][Not invited]
   

  Avian influenza viruses A/duck/Mongolia/47/2001 (H7N1) (47/01) and A/duck/Mongolia/867/2002 (H7N1) (867/02) were defined as low-pathogenic avian influenza viruses (LPAIVs) using an intravenous pathogenicity test in chickens. On the other hand, the intracerebral pathogenicity indices of 47/01 and 867/02 were 1.30 and 0.00, respectively. A series of reassortant viruses were generated between 47/01 and 867/02, and their intracerebral pathogenicity was compared in one-day-old chicks to identify the protein(s) responsible for the intracerebral pathogenicity of 47/01. The results indicate that the amino acids at positions 50 and 98 of the nucleoprotein are related to the pathogenicity of 47/01 in chicks by intracerebral inoculation. A significant association was found between mortality of the chicks inoculated intracerebrally with 47/01 and virus replication in the lungs and/or brain. These results indicate that the NP of avian influenza viruses may be responsible for intracerebral pathogenicity in the host.
• Recovery of Leptospires from Miniature Pigs Experimentally Infected with Leptospira interrogans Serovar Manilae Strain UP-MMC under Immunosuppressive Conditions by Dexamethasone

  Yoshihiro Sakoda, Michiko Naito, Mutsumi Ito, Yuki Ito, Norikazu Isoda, Tomohisa Tanaka, Takashi Umemura, Hiroshi Kida

  JOURNAL OF VETERINARY MEDICAL SCIENCE 74 (7) 955 - 958 0916-7250 2012/07 [Refereed][Not invited]
   

  Leptospira interrogans serovar Manilae strain UP-MMC was inoculated into miniature pigs to assess its pathogenicity. Leptospires were recovered from the whole blood, kidneys, and livers in the acute phase without showing any clinical signs. Under immunosuppressive conditions by dexamethasone, leptospires were recovered from the kidneys and their genes were detected from the urine in the chronic phase. These results indicate that leptospires persisted in the kidneys until the chronic phase, and excretion of leptospires in the urine was enhanced under immunosuppressive conditions, resulting in horizontal transmission among pigs on farms.
• Purification of human and avian influenza viruses using cellulose sulfate ester (Cellufine Sulfate) in the process of vaccine production

  Yoshihiro Sakoda, Masatoshi Okamatsu, Norikazu Isoda, Naoki Yamamoto, Koichi Ozaki, Yasuto Umeda, Shigeyuki Aoyama, Hiroshi Kida

  MICROBIOLOGY AND IMMUNOLOGY 56 (7) 490 - 495 0385-5600 2012/07 [Refereed][Not invited]
   

  Affinity chromatography using sulfated, spherical cellulose beads (Cellufine Sulfate) was assessed for purification of influenza A and influenza B viruses. Recovery rates of viruses eluted from the beads were high for all tested virus strains. This method was also useful for removing chicken egg-derived impurities from allantoic fluids containing influenza viruses; the hemagglutination activity per amount of protein in the eluted sample was significantly higher than that in the applied sample. These results suggest that use of Cellufine Sulfate is a practical method for primary purification of influenza viruses in the process of influenza vaccine production.
• Improvement of the H5N1 influenza virus vaccine strain to decrease the pathogenicity in chicken embryos

  Norikazu Isoda, Yoshihiro Sakoda, Masatoshi Okamatsu, Yoshimi Tsuda, Hiroshi Kida

  ARCHIVES OF VIROLOGY 156 (4) 557 - 563 0304-8608 2011/04 [Refereed][Not invited]
   

  The avian influenza vaccine strain A/duck/Hokkaido/Vac-1/2004 (H5N1) (Vac-1) was found to be pathogenic in chicken embryos (CEs). In order to decrease the pathogenicity of Vac-1 in CEs, a series of reassortant viruses was generated between Vac-1 and A/Puerto Rico/8/1934 (H1N1) (PR8), and their pathogenicity and growth potential were compared in CEs. The results indicated that either the PB1 or PA protein was responsible for the pathogenicity of Vac-1 in CEs. The HA titers of the allantoic fluids of CEs inoculated with the recombinant H5N1 viruses, of which pathogenicity was lower than that of the recombinant Vac-1 prepared by reverse genetics in CEs, were equivalent to those of CEs inoculated with the recombinant Vac-1. One of the reassortant viruses, rg-PR8-PA/Vac-1 (H5N1), in which the PA gene was replaced with the corresponding gene of PR8, yielded allantoic fluids with the same HA titer as that of Vac-1, indicating that this reassortant should be a good candidate as an improved vaccine strain.
• Detection of highly pathogenic avian influenza virus infection in vaccinated chicken flocks by monitoring antibodies against non-structural protein 1 (NS1)

  Natsumi Takeyama, Kenji Minari, Masahiro Kajihara, Norikazu Isoda, Ryuichi Sakamoto, Takashi Sasaki, Norihide Kokumai, Noriyasu Takikawa, Rikiya Shiraishi, Masaji Mase, Junko Hagiwara, Toshiaki Kodama, Takashi Imamura, Masashi Sakaguchi, Toshiaki Ohgitani, Akira Sawata, Masatoshi Okamatsu, Masatake Muramatsu, Kenji Tsukamoto, Zhifeng Lin, Kotaro Tuchiya, Yoshihiro Sakoda, Hiroshi Kida

  VETERINARY MICROBIOLOGY 147 (3-4) 283 - 291 0378-1135 2011/01 [Refereed][Not invited]
   

  H5 and H7 highly pathogenic avian influenza virus (HPAIV) represent a major global concern in poultries and human health. Avian influenza (AI) vaccines are available but not preferred for field applications, primarily because vaccination interferes with sero-surveillances of AIV infection. To overcome the problem, ELISA systems using nonstructural protein 1 (NS1) of AIV as antigens (NS1-ELISA) have been developed to measure anti-NS1 antibodies that are raised in AIV-infected but not in vaccinated chickens. However, some AI-vaccinated chickens having a weak anti-virus immune response may subsequently be infected with AIV and spread the virus. This raises a concern for the validity of NS1-ELISA to detect AIV infection in previously vaccinated chickens. In this study, we developed NS1-ELISA and assessed its feasibility to detect HPAIV infection in chickens previously immunized with H5 or H7 AI vaccines. The results indicated that the NS1-ELISA could identify HPAIV infection in both unvaccinated and vaccinated chickens at 1 week after infection in correlation with results from time-consuming virus isolation tests. Taken together, the NS1-ELISA system would be valuable tool to define HPAIV infection when AI vaccine program is in place. (C) 2010 Elsevier B.V. All rights reserved.
• Antigenic, genetic, and pathogenic characterization of H5N1 highly pathogenic avian influenza viruses isolated from dead whooper swans (Cygnus cygnus) found in northern Japan in 2008

  Masatoshi Okamatsu, Tomohisa Tanaka, Naoki Yamamoto, Yoshihiro Sakoda, Takashi Sasaki, Yoshimi Tsuda, Norikazu Isoda, Norihide Kokumai, Ayato Takada, Takashi Umemura, Hiroshi Kida

  VIRUS GENES 41 (3) 351 - 357 0920-8569 2010/12 [Refereed][Not invited]
   

  In April and May 2008, whooper swans (Cygnus cygnus) were found dead in Hokkaido in Japan. In this study, an adult whooper swan found dead beside Lake Saroma was pathologically examined and the identified H5N1 influenza virus isolates were genetically and antigenically analyzed. Pathological findings indicate that the swan died of severe congestive edema in the lungs. Phylogenetic analysis of the HA genes of the isolates revealed that they are the progeny viruses of isolates from poultry and wild birds in China, Russia, Korea, and Hong Kong. Antigenic analyses indicated that the viruses are distinguished from the H5N1 viruses isolated from wild birds and poultry before 2007. The chickens vaccinated with A/duck/Hokkaido/Vac-1/2004 (H5N1) survived for 14 days after challenge with A/whooper swan/Hokkaido/1/2008 (H5N1), although a small amount of the challenge virus was recovered from the tissues of the birds. These findings indicate that H5N1 highly pathogenic avian influenza viruses are circulating in wild birds in addition to domestic poultry in Asia and exhibit antigenic variation that may be due to vaccination.
• Characterization of H5N1 highly pathogenic avian influenza virus strains isolated from migratory waterfowl in Mongolia on the way back from the southern Asia to their northern territory

  Yoshihiro Sakoda, Sengee Sugar, Damdinjav Batchluun, Tseren-Ochir Erdene-Ochir, Masatoshi Okamatsu, Norikazu Isoda, Kosuke Soda, Hiroki Takakuwa, Yoshimi Tsuda, Naoki Yamamoto, Noriko Kishida, Keita Matsuno, Eri Nakayama, Masahiro Kajihara, Ayaka Yokoyama, Ayato Takada, Ruuragchaa Sodnomdarjaa, Hiroshi Kida

  VIROLOGY 406 (1) 88 - 94 0042-6822 2010/10 [Refereed][Not invited]
   

  H5N1 highly pathogenic avian influenza (HPAI) viruses were isolated from dead wild waterfowl at Khunt, Erkhel, Doityn Tsagaan, Doroo, and Ganga Lakes in Mongolia in July 2005, May 2006, May 2009, July 2009, and May 2010, respectively. The isolates in 2005 and 2006 were classified into genetic clade 2.2, and those in 2009 and 2010 into clade 2.3.2. A/whooper swan/Mongolia/6/2009 (H5N1) experimentally infected ducks and replicated systemically with higher mortality than that of the isolates in 2005 and 2006. Intensive surveillance of avian influenza in migratory waterfowl flying from their nesting lakes in Siberia to Mongolia in every autumn indicate that HPAI viruses have not perpetuated at their nesting lakes until 2009. The present results demonstrate that wild waterfowl were sporadically infected with H5N1 HPAI viruses prevailing in domestic poultry in the southern Asia and died in Mongolia on the way back to their northern territory in spring. (C) 2010 Elsevier Inc. All rights reserved.
• Novel trivalent anti-influenza reagent

  Fei Feng, Nobuaki Miura, Norikazu Isoda, Yoshihiro Sakoda, Masatoshi Okamatsu, Hiroshi Kida, Shin-Ichiro Nishimura

  BIOORGANIC & MEDICINAL CHEMISTRY LETTERS 20 (12) 3772 - 3776 0960-894X 2010/06 [Refereed][Not invited]
   

  We designed and synthesized novel trivalent anti-influenza reagents. Sialyllactose was located at the terminal of each valence which aimed to block each receptor-binding site of the hemagglutinin (HA) trimer on the surface of the virus. Structural analyses were carried out with a model which was constructed with a computer simulation. A previously reported cyclic glycopeptide blocker [Ohta, T.; Miura, N.; Fujitani, N.; Nakajima, F.; Niikura, K.; Sadamoto, R.; Guo, C.-T.; Suzuki, T.; Suzuki, Y.; Monde, K.; Nishimura, S.-I. Angew. Chem. Int. Ed., 2003, 42, 5186] bound to the HA in the model. The analyses suggest that the glutamine residue in the cyclic peptide bearing Neu5A alpha 2,3Gal beta 1,4Glc trisaccharide via a linker interacts with the Gln189 in HA through hydrogen bonding. The present anti-influenza reagents likely interact with a glutamine residue included in the vicinity of Gln189. A plague reduction assay of the influenza virus, A/PR/8/1934 (H1N1),was performed in MDCK cells to evaluate for the synthesized compounds to inhibit viral replication. One of the compounds showed approximately 85% inhibition at the concentration of 400 mu M at 4 degrees C. (C) 2010 Elsevier Ltd. All rights reserved.
• Subcutaneous inoculation of a whole virus particle vaccine prepared from a non-pathogenic virus library induces protective immunity against H7N7 highly pathogenic avian influenza virus in cynomolgus macaques

  Yasushi Itoh, Hiroichi Ozaki, Hirohito Ishigaki, Yoshihiro Sakoda, Tomoya Nagata, Kosuke Soda, Norikazu Isoda, Taichiro Miyake, Hideaki Ishida, Kiyoko Okamoto, Misako Nakayama, Hideaki Tsuchiya, Ryuzo Torii, Hiroshi Kida, Kazumasa Ogasawara

  VACCINE 28 (3) 780 - 789 0264-410X 2010/01 [Refereed][Not invited]
   

  Development of H7N7 highly pathogenic avian influenza virus (HPAIV) vaccines is an urgent issue since human cases of infection with this subtype virus have been reported and most humans have no immunity against H7N7 viruses. We made an H7N7 vaccine combining components from an influenza virus library of non-pathogenic type A influenza viruses Antibody and T cell recall responses specific against the vaccine strain were elicited by subcutaneous inoculation with the whole virus particle vaccine with or without alum as an adjuvant in cynomolgus macaques. No significant difference was observed in magnitude of antibody responses between vaccination with alum and vaccination without alum, though vaccination with alum induced longer recall responses of CD8(+) T cells than did vaccination without alum. After challenge with a subtype of H7N7 HPAIV, the virus was detected in nasal swabs of unvaccinated macaques for 8 days but only for I day in the animals vaccinated either with or without alum, although the macaques vaccinated with alum showed elevated body temperature more briefly after infection. These findings demonstrated that this H7N7 HPAIV strain is pathogenic to macaques and that the vaccine conferred protective immunity to macaques against H7N7 HPAIV infection. (C) 2009 Elsevier Ltd. All rights reserved.
• Hemagglutinin-Dependent Tropism of H5N1 Avian Influenza Virus for Human Endothelial Cells

  Manuela Ocana-Macchi, Michael Bel, Laurence Guzylack-Piriou, Nicolas Ruggli, Matthias Liniger, Kenneth C. McCullough, Yoshihiro Sakoda, Norikazu Isoda, Mikhail Matrosovich, Artur Summerfield

  JOURNAL OF VIROLOGY 83 (24) 12947 - 12955 0022-538X 2009/12 [Refereed][Not invited]
   

  Although current H5N1 highly pathogenic avian influenza viruses (HPAIV) are inefficiently transmitted to humans, infected individuals can suffer from severe disease, often progressing rapidly to acute respiratory distress syndrome and multiorgan failure. This is in contrast with the situation with human influenza viruses, which in immunocompetent individuals usually cause only a respiratory disease which is less aggressive than that observed with avian H5N1 viruses. While the biological basis of inefficient transmission is well documented, the mechanisms by which the H5N1 viruses cause fatal disease remain unclear. In the present study, we demonstrate that human pulmonary microvascular endothelial cells (hPMEC) had a clearly higher susceptibility to infection by H5N1 HPAIV than to infection by human influenza viruses. This was measurable by de novo intracellular nucleoprotein production and virus replication. It was also related to a relatively higher binding capacity to cellular receptors. After infection of hPMEC, cell activation markers E-selectin and P-selectin were upregulated, and the proinflammatory cytokines interleukin-6 and beta interferon were secreted. H5N1 virus infection was also associated with an elevated rate of cell death. Reverse genetics analyses demonstrated a major role for the viral hemagglutinin in this cell tropism. Overall, avian H5N1 viruses have a particular receptor specificity targeting endothelial cells that is different from human influenza viruses, and this H5N1 receptor specificity could contribute to disease pathogenesis.
• Generation of congenic mouse strains by introducing the virus-resistant genes, Mx1 and Oas1b, of feral mouse-derived inbred strain MSM/Ms into the common strain C57BL/6J

  Kanako Moritoh, Hideto Yamauchi, Atsushi Asano, Kentaro Yoshii, Hiroaki Kariwa, Ikuo Takashima, Norikazu Isoda, Yoshihiro Sakoda, Hiroshi Kida, Nobuya Sasaki, Takashi Agui

  JAPANESE JOURNAL OF VETERINARY RESEARCH 57 (2) 89 - 99 0047-1917 2009/08 [Refereed][Not invited]
   

  Mx1 (Myxovirus resistance protein) and Oas1b (Oligoadenylate synthetase-1), induced by type 1 interferon (IFN), play a role in early antiviral innate immunity by inhibiting the replication of viruses. In mice, Mx1 and Oas1b confer resistance to the infection of orthomyxoviruses including influenza viruses and flaviviruses including West Nile viruses, respectively. Laboratory mice have been used to study the mechanisms of the pathogenesis of these virus infections; however, it is possible that they are not a suitable model system to study these viruses, since most of the inbred laboratory mouse strains lack both genes. It has been reported that feral mouse-derived inbred strains show resistance to the infection of these viruses due to the presence of intact both genes. In this study, we generated congenic strains in which the Mx or Oas locus of the MSM/Ms (MSAI) mouce was introduced to the most widely used mouse strain, C57BL/6J (136). B6.MSM-Mx mice showed resistance to the infection of influenza virus but not of West Nile virus. On the other hand, B6.MSM-Oas mice showed resistance to the infection of West Nile virus but not of influenza virus. Our results indicate that Mx1 and Oas1b show highly antiviral specificity in mice possessing the same genetic background. Therefore, these congenic mice are useful for not only infection study but also investigation of host defense mechanism to these viruses.
• Factors responsible for plaque formation of A/duck/Siberia/272/1998 (H13N6) influenza virus on MDCK cells

  Yoshimi Tsuda, Norikazu Isoda, Yoshihiro Sakoda, Hiroshi Kida

  VIRUS RESEARCH 140 (1-2) 194 - 198 0168-1702 2009/03 [Refereed][Not invited]
   

  Many influenza A viruses form plaques on Madin-Darby canine kidney (MDCK) cells in the presence of trypsin. A/duck/Siberia/272/1998 (H13N6) (Sib272), however, does not form plaque on MDCK cells. After three blind passages of the strain on MDCK cells, plaque-forming variant was obtained and designated as A/duck/Siberia/272PF/1998 (H13N6) (Sib272PF). Genetic and functional analyses of Sib272 and Sib272PF revealed that amino acid substitutions, F3L of the HA2 subunit and T379K of the PB1, were responsible for plaque formation of Sib272PF by enhancing fusion and polymerase activities, respectively. (c) 2009 Elsevier B.V. All rights reserved.
• Evaluation of the potency, optimal antigen level and lasting immunity of inactivated avian influenza vaccine prepared from H5N1 virus

  Takashi Sasaki, Norikazu Isoda, Kosuke Soda, Ryuichi Sakamoto, Kazue Saijo, Junko Hagiwara, Norihide Kokumai, Toshiaki Ohgitani, Takashi Imamura, Akira Sawata, Zhifeng Lin, Yoshihiro Sakoda, Hiroshi Kida

  JAPANESE JOURNAL OF VETERINARY RESEARCH 56 (4) 189 - 198 0047-1917 2009/02 [Refereed][Not invited]
   

  Test vaccines comprised of inactivated water-in-oil emulsions containing various antigen levels were prepared using a non-pathogenic H5N1 avian influenza (AI) virus, A/duck/Hokkaido/Vac-1/04 (H5N1). The potencies of these test vaccines were evaluated by two experiments. In the first experiment, the triangular relationship among the antigen levels of test vaccines, the hemagglutination inhibition (HI) antibody response, and the protective effect against challenge with a highly pathogenic avian influenza (HPAI) virus, A/chicken/Yamaguchi/7/04 (H5N1), was confirmed. Then lasting immunity of chickens after a single-shot vaccination was confirmed in the second experiment. As a result, complete protection after the challenge was observed in chickens immunized by test vaccines with an antigen level of 160 HA units/dose or higher. Thus, it was ascertained that the minimum antigen level in the AI vaccine was 160 RA units/dose, and the minimum HI antibody titer that could protect chickens from HPAI virus infection-related death was considered to be 1:16. Dose-dependent III antibody responses were observed in chickens after the vaccination. Thus, 640 RA units/dose was thought to be similar to the optimal antigen level. Alternatively, the HI antibody titers of chickens, injected with the vaccine containing 640 HA units/dose, were maintained at 1:181 or higher for 100 weeks after the single-shot vaccination.
• Antigenic structure of the hemagglutinin of H9N2 influenza viruses

  Masatoshi Okamatsu, Yoshihiro Sakoda, Noriko Kishida, Norikazu Isoda, Hiroshi Kida

  ARCHIVES OF VIROLOGY 153 (12) 2189 - 2195 0304-8608 2008/12 [Refereed][Not invited]
   

  The hemagglutinins (HAs) of H9 influenza viruses isolated from birds and mammals of different species were antigenically and genetically analyzed. Antigenic variants were selected from A/swine/Hong Kong/10/98 (H9N2) and A/duck/Hokkaido/13/00 (H9N2) in the presence of monoclonal antibodies (MAbs). Based on the reactivity patterns of these mutants with a panel of MAbs, at least five non-overlapping antigenic sites were defined using eight MAbs which recognized seven distinct epitopes on the H9 HA molecule. Based on the reactivity patterns with the panel of monoclonal antibodies, 21 H9N2 virus strains isolated from birds and mammals were divided into 7 antigenically distinct groups. The present findings indicate that it is important to monitor the antigenic variation in H9 influenza viruses. The panel of MAbs in the present study, thus, should be useful for detailed antigenic analysis of the H9 HAs for epidemiological studies, the selection of vaccine strains, and diagnosis.
• Antigenic and genetic analysis of H5 influenza viruses isolated from water birds for the purpose of vaccine use

  Kosuke Soda, Hiroichi Ozaki, Yoshihiro Sakoda, Norikazu Isoda, Yoshinari Haraguchi, Saori Sakabe, Noritaka Kuboki, Noriko Kishida, Ayato Takada, Hiroshi Kida

  ARCHIVES OF VIROLOGY 153 (11) 2041 - 2048 0304-8608 2008/11 [Refereed][Not invited]
   

  In order to prepare H5N1 influenza virus vaccine, the hemagglutinins (HAs) of 14 H5 virus isolates from water birds in Asia were antigenically and genetically analyzed. Phylogenetic analysis of the H5 HA genes revealed that 13 isolates belong to Eurasian and the other one to North American lineages. Each of the deduced amino acid sequences of the HAs indicated a non-pathogenic profile. Antigenic analysis using a panel of monoclonal antibodies recognizing six different epitopes on the HA of A/duck/Pennsylvania/10218/1984 (H5N2) and chicken antiserum to an H5N1 reassortant strain generated between A/duck/Mongolia/54/2001 (H5N2) and A/duck/Mongolia/47/2001 (H7N1), [R(Dk/Mong-Dk/Mong) (H5N1)] showed that the HAs of highly pathogenic avian influenza (HPAI) viruses currently circulating in Asia were antigenically closely related to those of the present isolates from water birds. Mice subcutaneously injected with formalin-inactivated R(Dk/Mong-Dk/Mong) were protected from challenge with 100 mouse lethal dose of A/Viet Nam/1194/2004 (H5N1). The present results support the notion that the H5 isolates and the reassortant H5N1 strain should be useful for vaccine preparation.
• Phylogenic analysis of the M genes of influenza viruses isolated from free-flying water birds from their Northern Territory to Hokkaido, Japan

  Rashid Manzoor, Yoshihiro Sakoda, Aaron Mweene, Yoshimi Tsuda, Noriko Kishida, Gui-Rong Bai, Ken-Ichiro Kameyama, Norikazu Isoda, Kosuke Soda, Michiko Naito, Hiroshi Kida

  VIRUS GENES 37 (2) 144 - 152 0920-8569 2008/10 [Refereed][Not invited]
   

  During 2000-2007, 218 influenza viruses of 28 different combinations of HA (H1-H13) and NA (N1-N9) subtypes were isolated from fecal samples of free-flying water birds at two distant lakes in Hokkaido, Japan. Phylogenic analysis of the matrix (M) genes of 67 strains, selected on the basis of their subtype combinations, revealed that A/duck/Hokkaido/W95/2006 (H10N8) was a reassortant whose M gene belonged to North American non-gull-avian and the other seven genes to Eurasian non-gull-avian lineages. The M genes of other 65 strains belonged to Eurasian non-gull-avian and the one to Eurasian-gull lineages. The M genes of 65 strains were grouped into three different sublineages, indicating that influenza viruses circulating in different populations of free-flying water birds have evolved independently in nature.
• Phylogenic analysis of the M genes of influenza viruses isolated from free-flying water birds from their Northern Territory to Hokkaido, Japan (Virus Genes DOI: 10.1007/s11262-008-0248-7)

  Rashid Manzoor, Yoshihiro Sakoda, Aaron Mweene, Yoshimi Tsuda, Noriko Kishida, Gui-Rong Bai, Ken-Ichiro Kameyama, Norikazu Isoda, Kosuke Soda, Michiko Naito, Hiroshi Kida

  Virus Genes 37 (2) 153  0920-8569 2008/10 [Refereed][Not invited]
  
• Potency of an inactivated avian influenza vaccine prepared from a non-pathogenic H5N1 reassortant virus generated between isolates from migratory ducks in Asia

  Norikazu Isoda, Yoshihiro Sakoda, Noriko Kishida, Kosuke Soda, Saori Sakabe, Ryuichi Sakamoto, Takashi Imamura, Masashi Sakaguchi, Takashi Sasaki, Norihide Kokumai, Toshiaki Ohgitani, Kazue Saijo, Akira Sawata, Junko Hagiwara, Zhifeng Lin, Hiroshi Kida

  ARCHIVES OF VIROLOGY 153 (9) 1685 - 1692 0304-8608 2008/09 [Refereed][Not invited]
   

  A reassortant influenza virus, A/duck/Hokkaido/Vac-1/2004 (H5N1) (Dk/Vac-1/04), was generated between non-pathogenic avian influenza viruses isolated from migratory ducks in Asia. Dk/Vac-1/04 (H5N1) virus particles propagated in embryonated chicken eggs were inactivated with formalin and adjuvanted with mineral oil to form a water-in-oil emulsion. The resulting vaccine was injected intramuscularly into chickens. The chickens were challenged with either of the highly pathogenic avian influenza virus strains A/chicken/Yamaguchi/7/2004 (H5N1) or A/swan/Mongolia/3/2005 (H5N1) at 21 days post-vaccination (p. v.), when the geometric mean serum HI titers of the birds was 64 with the challenge virus strains. The vaccinated chickens were protected from manifestation of disease signs upon challenge with either of the highly pathogenic avian influenza viruses. However, challenge virus was recovered at low titers from the birds at 2 and 4 days post-challenge (p.c.). All 3 chickens challenged at 6 days p.v. died, whereas 3 chickens challenged at 8 days p.v. survived. These results indicate that the present vaccine confers clinical protection and reduction of virus shedding against highly pathogenic avian influenza virus challenge and should be useful as an optional tool in emergency cases.
• H2N5 influenza virus isolates from terns in Australia: genetic reassortants between those of the Eurasian and American lineages

  Noriko Kishida, Yoshihiro Sakoda, Mai Shiromoto, Gui-Rong Bai, Norikazu Isoda, Ayato Takada, Graeme Laver, Hiroshi Kida

  VIRUS GENES 37 (1) 16 - 21 0920-8569 2008/08 [Refereed][Not invited]
   

  To investigate the prevalence of influenza viruses in feral water birds in the Southern Hemisphere, fecal samples of terns were collected on Heron Island, Australia, in December 2004. Six H2N5 influenza viruses were isolated. This is the first report of the isolation of the H2 subtype from shore birds in Australia. Phylogenetic analysis revealed that the M gene belonged to the American lineage of avian influenza viruses and the other genes belonged to the Eurasian lineages, indicating that genetic reassortment occurs between viruses of Eurasian and American lineages in free flying birds in nature.
• Induction of cytotoxic T-lymphocyte and antibody responses against highly pathogenic avian influenza virus infection in mice by inoculation of apathogenic H5N1 influenza virus particles inactivated with formalin

  Toshihiro Sawai, Yasushi Itoh, Hiroichi Ozaki, Norikazu Isoda, Kiyoko Okamoto, Yoshitaka Kashima, Yoshihiro Kawaoka, Yoshihiro Takeuchi, Hiroshi Kida, Kazumasa Ogasawara

  IMMUNOLOGY 124 (2) 155 - 165 0019-2805 2008/06 [Refereed][Not invited]
   

  We investigated whether a vaccine derived from an apathogenic reassortant type A H5N1 influenza strain could induce immune responses in vivo that mediated protection from highly pathogenic avian influenza virus infection in mice. After two subcutaneous immunizations with formalin-inactivated H5N1 whole virus particles (whole particle vaccine), significant killing specific for cells presenting a nucleoprotein peptide from the vaccine strain of the virus was observed. Similar vaccination with viruses treated with ether and formalin, which are commonly used for humans as ether-split vaccines, induced little or no cytotoxic T-cell response. Furthermore, whole particle vaccines of the apathogenic H5N1 strain were more effective than ether-split vaccines at inducing antibody production able to neutralize a highly pathogenic H5N1 strain. Finally, whole particle vaccines of H5N1 protected mice against infection by an H5N1 highly pathogenic avian influenza virus more effectively than did ether-split vaccines. These results suggest that formalin-inactivated virus particles of apathogenic strains are effective for induction of both cytotoxic T-lymphocyte and antibody responses against highly pathogenic avian influenza viruses in vivo, resulting in protection from infection by a highly pathogenic H5N1 virus.
• A vaccine prepared from a non-pathogenic H7N7 virus isolated from natural reservoir conferred protective immunity against the challenge with lethal dose of highly pathogenic avian influenza virus in chickens

  Saori Sakabe, Yoshihiro Sakoda, Yoshinari Haraguchi, Norikazu Isoda, Kosuke Soda, Hiroki Takakuwa, Kazue Saijo, Akira Sawata, Katsumi Kume, Junko Hagiwara, Kotaro Tuchiya, Zhifeng Lin, Ryuichi Sakamoto, Takashi Imamura, Takashi Sasaki, Norihide Kokumai, Yoshihiro Kawaoka, Hiroshi Kida

  VACCINE 26 (17) 2127 - 2134 0264-410X 2008/04 [Refereed][Not invited]
   

  During 2001-2004, 41 H7 influenza viruses (2 H7N1 and 39 H7N7 strains) were isolated from fecal samples of migratory ducks that flew from Siberia in the autumn of each year to Japan and Mongolia. A phylogenetic analysis of the hemagglutinin (HA) genes of the nine representative isolates revealed that they belonged to the Eurasian Lineage and the deduced amino acid sequence at the cleavage site of the HAs represented apathogenic profiles. One of the H7 isolates A/duck/Mongolia/736/02 (H7N7) was chosen from these H7 isolates for the preparation of the test vaccine. To improve the growth potential of A/duck/Mongolia/ 736/02 (H7N7) in chicken embryos, A/duck/Hokkaido/Vac-2/04 (H7N7) was generated by genetic reassortment between A/duck/Mongolia/736/02 (H7N7) as the donor of the PB2, PB1, PA, HA, NA, and NS genes and A/duck/Hokkaido/49/98 (H9N2) as that of NP and M genes. The test vaccine was prepared as follows; A/duck/Hokkaido/Vac-2/04 (H7N7) was propagated in chicken embryos and the virus in the allantoic fluid was inactivated and adjuvanted to form an oil-in-water emulsion. The test vaccine conferred immunity to chickens, completely protecting the manifestation of clinical signs against the challenge with lethal dose of H7 highly pathogenic avian influenza virus. These results indicate that influenza viruses isolated from natural reservoirs are useful for vaccine strains. (C) 2008 Elsevier Ltd. All rights reserved.
• Development of vaccine strains of H5 and H7 influenza viruses

  Kosuke Soda, Yoshihiro Sakoda, Norikazu Isoda, Masahiro Kajihara, Yoshinari Haraguchi, Hitomi Shibuya, Hiromi Yoshida, Takashi Sasaki, Ryuichi Sakamoto, Kazue Saijo, Junko Hagiwara, Hiroshi Kida

  JAPANESE JOURNAL OF VETERINARY RESEARCH 55 (2-3) 93 - 98 0047-1917 2008/01 [Refereed][Not invited]
   

  To establish vaccine strains of H5 and H7 influenza viruses, A/duck/Hokkaido/Vac-1/04 (H5N1) [Vac-1/04 (H5N1)], A/duck/Hokkaido/Vac-3/07 (H5N1) [Vac-3/07 (H5N1)], and A/duck/Hokkaido/ Vac-2/04 (H7N7) [Vac-2/04 (H7N7)] were generated from non-pathogenic avian influenza viruses isolated from migratory ducks. Vac-1/04 (H5N1) and Vac-3/07 (H5N1) were generated by genetic reassortment between H5N2 or H5N3 virus as an HA gene provider and H7N1 or H6N1 viruses as an NA gene provider. Vac-2/04 (H7N7) was a genetic reassortant obtained using H7N7 and H9 N2 viruses to give high growth character of the H9N2 virus in chicken embryonated eggs. The results of sequence analyses and experimental infections revealed that these H5N1 and H7N7 reassortant viruses were non-pathogenic in chickens and embryos, and had good growth potential in embryonated eggs. These viruses should be useful to develop vaccines against H5 and H7 highly pathogenic avian influenza viruses.
• Pathogenicity of a highly pathogenic avian influenza virus, A/chicken/Yamaguchi/7/04 (H5N1) in different species of birds and mammals.

  N Isoda, Y Sakoda, N Kishida, G-R Bai, K Matsuda, T Umemura, H Kida

  Archives of virology 151 (7) 1267 - 79 0304-8608 2006/07 

  Outbreaks of highly pathogenic avian influenza (HPAI) have been occurring in domestic poultry in Asia since 1996. In the beginning of 2004, HPAI outbreaks were caused by H5N1 virus in two farms and a group of pet chickens in different areas of Japan. In the present study, the pathogenicity of A/chicken/Yamaguchi/7/04 (H5N1), which had been isolated from a dead chicken during the first outbreak in Japan, was assessed in chickens, quails, budgerigars, ducklings, mice, and miniature pigs by experimental infection. The virus was highly pathogenic to all the birds tested. Mice were susceptible to infection with a low mortality rate and miniature pigs were resistant to infection with the virus.
• Pathogenicity of H5 influenza viruses for ducks

  N Kishida, Y Sakoda, N Isoda, K Matsuda, M Eto, Y Sunaga, T Umemura, H Kida

  ARCHIVES OF VIROLOGY 150 (7) 1383 - 1392 0304-8608 2005/07 [Refereed][Not invited]
   

  Four H5N1 highly pathogenic avian influenza (HPAI) viruses and an avirulent reassortant H5N1 virus were tested for their pathogenicity in domestic ducks. A/chicken/Yamaguchi/7/04 (H5N1) (Ck/Yamaguchi/04) isolated from a dead bird during the HPAI outbreak in Japan and A/duck/Yokohama/aq-10/03 (H5N1) (Dk/Yokohama/03) isolated from duck meat at a quarantine inspection for importation from China replicated in multiple organs including the brain of ducks. The ducks infected with Ck/Yamaguchi/04 did not show any clinical signs, while those infected with Dk/Yokohama/03 showed neurological signs. The ducks infected either with A/Hong Kong/483/97 (H5N1) orA/tern/SouthAfrica/61 (H5N3), or with an avirulent H5N1 reassortant, did not show any clinical signs. Virus-specific antibodies were detected in the sera of the ducks infected with each of the five strains tested, indicating that all of the viral strains infected and replicated in the birds. Dk/Yokohama/03 grew in multiple organs more rapidly than did Ck/Yamaguchi/04. Considerable titers of virus were detected in the brain of the ducks infected with Dk/Yokohama/03 and these birds showed neurological signs. The present results demonstrate that the pathogenicity of influenza viruses for ducks does not correlate with that for chickens and that replication of the virus in the brain is critical for ducks to show neurological signs.

Conference Activities & Talks

• 日本および世界で今冬報告された鳥インフルエンザウイルス  [Not invited]

  磯田典和

  第57回獣医疫学会  2021/03
• 時空間解析を用いた日本における野生イノシシ群での豚コレラ感染拡大評価  [Not invited]

  磯田典和, 馬場開陸, 伊藤聡, 伊藤貢, 迫田義博, 蒔田浩平

  第56回獣医疫学会  2020/09
• 日本における牛ウイルス性下痢症に対する着地検査およびバルク乳検査の費用対効果  [Not invited]

  磯田典和, 浅野明弘, 一條満, 大野浩, 佐藤一彦, 岡本浩一, 中尾茂, 加藤肇, 斉藤一真, 伊藤直樹, 臼井章, 高山裕章, 迫田義博

  平成30年度北海道獣医師会地区学会  2018/08
• Assessment of antimicrobial resistant Enterobacteriaceae in pigs for development of comprehensive management system  [Invited]

  Norikazu Isoda

  Philippine Society of Animal science

MISC

• Comparison of the Hygiene Management Practices between Classical Swine Fever (CSF)-Infected and Non-Infected Farms in the CSF-Occurred Prefectures

  浮田真琴, 磯田典和, 山本健久, 蒔田浩平  獣医疫学雑誌  26-  (1)  2022
• 国内で流行している牛ウイルス性下痢ウイルスは,遺伝子型1bおよび2aが主流である

  西森朝美, 安藤清彦, 迫田義博, 磯田典和, 廣瀬静香, 荻野紗帆  農研機構動物衛生研究部門成果情報(Web)  2021-  2021
• Prediction of the Change of CSF Antibody Titers of Sow Herds by Generation Using a Simulation Model

  浮田真琴, 桑田桂輔, 田中英次, 磯田典和, 迫田義博, 蒔田浩平  獣医疫学雑誌  25-  (1)  2021
• 高病原性鳥インフルエンザウイルスの自然感染が確認されたオジロワシの事例

  小笠原浩平, 藤本佳万, 畑井仁, 磯田典和, 渡辺有希子, 大沼学, 小澤真, 迫田義博, 齊藤慶輔  北海道獣医師会雑誌  65-  (8)  2021
• 豚熱農場ワクチン開始時期に基づくシミュレーションモデルによる地域別ワクチンプログラムの検討

  浮田真琴, 桑田桂輔, 田中英次, 磯田典和, 迫田義博, 蒔田浩平  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• 2014年から2020年に日本で分離された牛ウイルス性下痢ウイルスの遺伝子解析

  荻野紗帆, 西森朝美, 廣瀬静香, 磯田典和, 磯田典和, 日尾野隆大, 安藤清彦, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• シチメンチョウの気管上皮に発現する多様な鳥インフルエンザウイルスレセプターの構造解析

  小林大樹, 市居修, 日尾野隆大, 西原祥子, 高瀬明, 磯田典和, 磯田典和, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• 2020年度冬季に東日本の野鳥から分離された高病原性鳥インフルエンザウイルスの性状

  磯田典和, 磯田典和, 日尾野隆大, TWABELA Augustin T., BAZARRAGCHAA Enkhbold, KIEN Le Trung, LOC Huynh Tan, 小笠原浩平, 林裕貴, 渡辺有希子, 齊藤慶輔, 喜田宏, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• アミノレブリン酸リン酸塩による豚熱ウイルス増殖抑制効果の検証

  廣瀬静香, LOC Huynh Tan, 金琢珠, 磯田典和, 磯田典和, 日尾野隆大, 吉本圭一郎, 田中徹, 乾健二郎, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• ワクチンシードと同じアミノ酸配列を持つ豚熱ウイルスGPE^-株作出の試み

  金琢洙, LOC Huynh Tan, 廣瀬静香, 日尾野隆大, 磯田典和, 磯田典和, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• Generation of recombinant highly virulent classical swine fever virus strain possessing a luminescent HiBiT tag as a reporter

  LOC Huynh Tan, 廣瀬静香, 金琢洙, 田村友和, 福原崇介, 松浦善治, 日尾野隆大, 磯田典和, 磯田典和, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• インフルエンザウイルスライブラリーを活用したパンデミックインフルエンザ対策

  野村直樹, 新開大史, 松野啓太, 関屋俊輝, 関屋俊輝, 大野円実, 磯田典和, 迫田義博, 喜田宏, 喜田宏  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• The pioneering study on impact identification of low pathogenicity avian influenza virus infection in the farm in southern Vietnam

  LE Trung Kien, 磯田典和, 磯田典和, NGUYEN Thanh Lam, NGUYEN Thanh Lam, CHU Duc-Huy, TIEN Ngoc Tien, LE Thanh Tung, 日尾野隆大, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• 豚熱ウイルスに対する各種動物用消毒薬の効果

  迫田義博, 迫田義博, 遠藤真由美, 伊藤貢, 日尾野隆大, 磯田典和, 磯田典和  日本獣医学会学術集会講演要旨集  164th (CD-ROM)-  2021
• 豚熱ウイルスに対する各種動物用消毒薬の効果

  迫田義博, 迫田義博, 遠藤真由美, 伊藤貢, 日尾野隆大, 磯田典和, 磯田典和  家畜衛生学雑誌  47-  (3)  2021
• マウスモデルにおけるインフルエンザウイルス感染に対するビタミンD代謝産物25(OH)D3の経口補給による効果

  林裕貴, 岡松正敏, 小笠原帆南, 津川尚子, 磯田典和, 松野啓太, 松野啓太, 迫田義博, 迫田義博  日本獣医学会学術集会講演要旨集  163rd-  2020
• 日本における牛ウイルス性下痢症に対する着地検査およびバルク乳検査の費用対効果

  磯田典和, 浅野明弘, 一條満, 大野浩, 佐藤一彦, 岡本浩一, 中尾茂, 加藤肇, 斉藤一真, 伊藤直樹, 臼井章, 高山裕章, 迫田義博  北海道獣医師会雑誌  62-  (8)  353  -353  2018/08/24  [Not refereed][Not invited]
  
• 2014-2017のベトナムにおけるH5高病原性鳥インフルエンザ発生の時空間・リスク解析(Spatiotemporal and risk analysis of H5 highly pathogenic avian influenza occurrence in Vietnam during 2014-2017)

  Nguyen Thanh-Lam, Stevenson Mark, Firestone Simon, Sims Les, Chu Huy, Nguyen Long, Nguyen Tien, 磯田 典和, 松野 啓太, 岡松 正敏, 喜田 宏, 迫田 義博  日本獣医学会学術集会講演要旨集  161回-  357  -357  2018/08  [Not refereed][Not invited]
  
• インフルエンザに立ち向かう 人獣共通感染症としてのインフルエンザ

  ISODA NORIKAZU, TAKADA AYATO  Mebio  30-  (12)  32  -41  2013/12/10  [Not refereed][Not invited]
  
• フィロウイルス糖蛋白質による宿主細胞表面分子の立体的遮蔽現象の解析

  野依修, 松野啓太, 梶原将大, 中山絵里, 五十嵐学, 磯田典和, 吉田玲子, 高田礼人  日本ウイルス学会学術集会プログラム・抄録集  60th-  198  2012/10/31  [Not refereed][Not invited]
  
• Preventive measures against highly pathogenic avian influenza

  ISODA Norikazu, SAKODA Yoshihiro  農林水産技術研究ジャーナル  32-  (12)  10  -15  2009/12/01  [Not refereed][Not invited]
  
• H5亜型ウイルスに対する鳥インフルエンザワクチンの開発 : 高力価のワクチンを開発. H7ウイルス用もスタンバイ

  磯田 典和, 迫田 義博, 喜田 宏  化学と生物  47-  (5)  302  -304  2009/05/01  [Not refereed][Not invited]
  
• 国内開発鳥インフルエンザワクチン

  佐々木 崇, 坂元 隆一, 今村 孝, 坂口 正士, 瀧川 義康, 西條 加須江, 澤田 章, 萩原 純子, 土屋 耕太郎, 林 志鋒, 國米 則秀, 扇谷 年昭, 曽田 公輔, 磯田 典和, 迫田 義博, 喜田 宏  鶏病研究会報  44-  (4)  170  -174  2009/02/25  [Not refereed][Not invited]
  
• 2008年北海道で発見された斃死オオハクチョウから分離したH5N1高病原性鳥インフルエンザウイルスの性状

  岡松正敏, 迫田義博, 吉田裕美, 田中智久, 津田祥美, 磯田典和, 中山絵里, 苫米地大輔, 松野啓太, 梅村孝司, 高田礼人, 喜田宏  日本ウイルス学会学術集会プログラム・抄録集  56th-  263  2008/10/01  [Not refereed][Not invited]
  
• 2008年北海道で発見された斃死オオハクチョウから分離したH5N1高病原性鳥インフルエンザウイルスの性状

  岡松正敏, 迫田義博, 吉田裕美, 田中智久, 津田祥美, 磯田典和, 中山絵里, 苫米地大輔, 松野啓太, 梅村孝司, 高田礼人, 喜田宏  日本獣医学会学術集会講演要旨集  146th-  193  2008/09/05  [Not refereed][Not invited]
  
• Concentration and purification of influenza viruses by sulfate ester of cellulose (Cellufine Sulfate (R))

  Kouichi Ozaki, Yasuto Umeda, Shigeyuki Aoyama, Norikazu Isoda, Masatoshi Okamatsu, Yoshihiro Sakoda  VACCINE  2008  [Not refereed][Not invited]
  
• 動物インフルエンザのグローバルサーベイランスと全ての亜型ウイルスライブラリーの構築

  梶原将大, 梶原将大, 迫田義博, 迫田義博, 伊藤壽啓, 高田礼人, 岸田典子, 五十嵐学, 磯田典和, 磯田典和, 曽田公輔, 曽田公輔, 喜田宏, 喜田宏, 喜田宏  日本ウイルス学会学術集会プログラム・抄録集  55th-  216  2007/10/01  [Not refereed][Not invited]
  
• 鳥インフルエンザに対するワクチンの開発

  磯田 典和, 喜田 宏  ファームステージ  7-  (6)  84  -87  2007/09  [Not refereed][Not invited]
  
• 動物インフルエンザのグローバルサーベイランスと全ての亜型ウイルスライブラリーの構築

  梶原将大, 梶原将大, 迫田義博, 迫田義博, 伊藤壽啓, 高田礼人, 伊藤公人, 岸田典子, 五十嵐学, 磯田典和, 磯田典和, 曽田公輔, 曽田公輔, WEBSTER R.G, 喜田宏, 喜田宏, 喜田宏  日本獣医学会学術集会講演要旨集  144th-  91  2007/08/27  [Not refereed][Not invited]
  

Research Grants & Projects

• Identification of risk factors and development of disease model of bovine viral diarrhea in beef cattle

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2022/04 -2025/03 

  Author : 磯田 典和
• Risk assessment of Bovine Viral Diarrhea by animal movement and vaccination

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

  Date (from‐to) : 2019/04 -2022/03 

  Author : 磯田 典和

   

  2019年度に実施を予定していた、移動履歴有無によるPI牛のコホート調査（実験1）および耳片組織材料を用いた診断感度の確認（実験2）について、未だ実施できていない。これは、当初調査を予定していた地方行政機関との協力が難しくなったことに起因しており、事態が変化した背景として、2018年より本邦にて発生している豚熱の流行が挙げられる。 それを受けて、2019年度はこれら野外フィールドでの疫学調査に協力いただける機関を、今までの研究で得られたネットワークを生かして探していたところ、2020年3月現在で、研究協力を前向きに検討していただける協力機関を見つけることができた。現在は先方での内部調整の結果を待ってはいるが、2020年8月から2021年3月までの期間にて、1)ならびに2)の実験を実施する予定でいる。 当初2019年度に予定していた疫学調査の実施であったが、上記の理由で実施できなかった。しかしながら、2019年度の終わりに研究の協力が可能な機関が見つかったため、2020年度の疫学調査実施のための診断試薬の購入や材料採取道具の用意を進めた。また研究協力機関に出張し、当方の研究計画の紹介および牛ウイルス性下痢症の現状や対策について意見交換も行った。 野外フィールド調査の実施調整だけではなく、2019年度は、当初協力予定期間から分与頂いた血清中の抗体データを用い、ワクチン接種された牛群における牛ウイルス性下痢症のリスクについて評価を行った。当初の予定にはなかったが、これらデータから得られる知見も当初の目的を遂行するために有用であるため、これらデータ解析をまとめ報告する予定である。
• 高病原性鳥インフルエンザワクチン株の樹立とヒト用ワクチンへの応用

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2007 -2007 

  Author : 磯田 典和

   

  日本では、高病原性鳥インフルエンザ(HPAI)の防疫対策としては摘発淘汰を基本とし、防圧が困難な非常時に備え、高力価のワクチンを備蓄しておく方針が採られている。そこで野生水禽から分離された2株の非病原性鳥インフルエンザウイルスの遺伝子再集合体H5N1ウイルス株を鶏胚で培養不活化し、生物製剤基準に準じてワクチンを試製した。本ワクチンを接種したニワトリをHPAIウイルスで攻撃し、免疫効果を評価した。攻撃株として、2004年山口県で発生したHPAIの病原ウイルスであるA/chicken/Yamaguchi/7/04(H5N1)およびモンゴル国で発見されたオオハクチョウの斃死体から分離されたHPAIウイルス、A/whooper swan/Mongolia/3/05(H5N1)株を用いた。いずれの場合もニワトリは臨床症状を示すことなく耐過した。作製したワクチンの効果発現日数を測定したところ、ワクチン接種後6日以内のニワトリは攻撃ウイルスにより全て死亡したが、ワクチン接種8日目のニワトリはHI抗体が検出されないにも拘わらず、HPAIウイルスの攻撃に対して耐過した。ワクチン接種後6ケ月のニワトリにおいても、HPAIウイルスの攻撃に十分耐過できる抗体価を有していることも確認された。これらの結果から、本ワクチンは日本国における鳥インフルエンザの緊急用備蓄ワクチンとして利用し得ることが明らかになった。以上の研究を踏まえ、ワクチン株の改良を主眼とした研究を引き続き行った。ワクチン株である、A/duck/Hokkaido/Vac-1/04(H5N1)(Dk/Vac-1/04)株は、静脈内接種によりニワトリに対して非病原性と判定されたが、鶏胚に対して中等度の病原性を示すことから、製造効率では不十分であることが示唆された。そこで、Dk/Vac-1/04株の鶏胚に対する病原性を決定する遺伝子を同定することを目的とした人工作出ウイルスを9日齢発育鶏卵の尿膜腔内に接種し、8時間毎にその生死を観察して、鶏胚の平均致死時間を算出したところ、PB1遺伝子およびPA遺伝子が鶏胚に対する病原性に関与することが判った。

Educational Activities

Teaching Experience