Language：Japanese   Publishing type：Research paper (scientific journal)  

The Izumi plain, located in the southern part of Japan, serves as a major overwintering site for endangered crane species, including the hooded crane (Grus monacha) and the white-naped crane (Grus vipio). Since the 2012/13 winter season, continuous surveillance of avian influenza viruses (AIVs) in environmental water and wild birds has been conducted in this region. During the 2023/24 winter season, 45 isolates of H5N1 high pathogenicity AIVs (HPAIVs) and 24 isolates of low pathogenicity AIVs (LPAIVs) were obtained at different time points from crane roost water. Additionally, H5N1 HPAIVs were detected in four wild ducks in November 2023 and in eight cranes in December 2023. Phylogenetic analyses revealed that all H5N1 HPAIVs belonged to subclade G2d of clade 2.3.4.4b, with early winter isolates-particularly those from wild ducks and roost water-occupying more ancestral phylogenetic positions. These findings suggest that wild ducks likely introduced HPAIVs into the overwintering site. Genotype analysis based on the genetic constellations of all eight gene segments indicated the co-introduction of multiple HPAIV genotypes into the Izumi plain and suggested bidirectional gene segment exchange between HPAIVs and LPAIVs. Hemagglutination inhibition assays detected no H5 HA-specific antibodies in six overwintering cranes, implying a limited role for cranes in virus dissemination. Collectively, these findings underscore the importance of continued virological surveillance and genetic monitoring of AIVs at major overwintering sites, where close ecological interactions between wild ducks and cranes facilitate cross-species transmission.

DOI： 10.1016/j.cimid.2025.102389

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/pathogens14100990

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/pathogens14090951

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Language：Japanese   Publishing type：Research paper (scientific journal)  

BACKGROUND: The accurate determination of bird sex is crucial in various biological fields, including ecology, behavioral research, and conservation. However, this task remains challenging in species in which males and females exhibit similar external morphologies, such as owls. Although polymerase chain reaction (PCR)-based molecular sexing techniques that target the chromodomain helicase DNA-binding protein 1 gene found on sex chromosomes Z (CHD1-Z gene) and W (CHD1-W gene) are widely used, we encountered atypical banding patterns when applying the previously reported primers 2550F and 2718R to four wild owls of unknown sex. This study aims to reveal the owl-specific genetic structure of the CHD1 gene. METHODS: We developed a new primer set and determined the nucleotide sequences-including the binding sites for the primers 2550F and 2718R-within both the CHD1-Z and CHD1-W genes. RESULTS: Sequencing analysis, conducted using a newly developed primer set that successfully amplified both Z- and W-derived CHD1 products across various owl species, revealed a unique genetic insertion of approximately 600 bp in intron 17 of the CHD1-W gene. This insertion reversed the usual length relationship between PCR products from the chromosomes Z and W. Additionally, mutations identified in the 2550F primer binding site of the CHD1-Z gene in certain owl species may explain the failure to amplify CHD1-Z-derived PCR products. CONCLUSION: These findings provide valuable insights for improving molecular sexing in owls.

DOI： 10.3390/genes16060653

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Language：English   Publisher：(公社)日本獣医学会  

Language：Japanese   Publishing type：Research paper (scientific journal)  

During the 2022-23 winter season, >1,500 endangered cranes, including hooded cranes (Grus monacha) and white-naped cranes (Grus vipio), were found debilitated or dead in the Izumi Plain, Japan. Most of the cranes, particularly those collected in November, were infected with highly pathogenic avian influenza (HPAI) H5N1 viruses; virus shedding was higher from the trachea than from the cloaca. The isolation rate from the cranes' roost water was not markedly higher than that of previous seasons, suggesting that the viruses might be more effectively transmitted among cranes via the respiratory route than through feces. Most wild bird-derived H5N1 isolates were phylogenetically distinct from viruses isolated on nearby chicken farms, indicating limited relationship between the wild bird and chicken isolates. Serologic analyses suggested that herd immunity had little effect on outbreak subsidence. This study deepens our understanding of the circumstances surrounding the unexpected HPAI outbreaks among these endangered cranes.

DOI： 10.3201/eid3105.241410

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE SOCIETY OF VETERINARY SCIENCE  

<p>Bovine leukemia virus (BLV), a retrovirus that is widespread worldwide, causes enzootic bovine leukosis (EBL), a B-cell leukemia/lymphoma with a poor prognosis that ultimately results in death. In Japan, the number of cattle infected with this virus is increasing, and it is estimated more than 35% of cattle are currently infected. Since no vaccines or treatments against BLV infection are currently available, it is important to establish a method of early diagnosis for EBL to reduce economic losses caused by the disposal of EBL cattle in Japan, where a large number of expensive beef cattle are raised. We previously developed Rapid Amplification of the Integration Site without Interference by Genomic DNA Contamination (RAISING), a cost-effective, rapid, and sensitive method for the clonality analysis of BLV-infected cells. Despite its usefulness for the early diagnosis of EBL, RAISING had drawbacks preventing its practical application. Here, we report the development of an improved method, RAISING ver.2, and its performance. Compared to BLV clonality analysis using the previous method, RAISING ver.2 was found to maintain high accuracy and reproducibility despite its simplification. Moreover, its performance was also validated in a multicenter validation study. Taken together, our results strongly suggest that RAISING ver.2 can be fully utilized in clinical practice. Successful commercialization of a RAISING test kit could overcome the concerns of livestock farmers suffering from EBL, thereby promoting a stable supply of Japanese beef, both domestically and internationally.</p>

DOI： 10.1292/jvms.25-0031

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Inclusion body disease of cranes (IBDCs) is fatal in many cases and reportedly caused by a herpes-like virus labeled as gruid herpesvirus 1 (GrHV-1). Although GrHV-1 has been isolated from IBDC-affected cranes, it has not been genetically classified because its genome has not been partially or fully sequenced. In this study, we isolated an alphaherpesvirus from hooded cranes (Grus monacha) diagnosed with IBDC in Japan. Next-generation sequencing revealed that this virus isolate was GrHV-1, based on the 99.98% sequence homology with a previously isolated GrHV-1 strain. Furthermore, phylogenetic analysis of eight conserved herpesvirus genes supported the taxonomic assignment of GrHV-1 to the genus Mardivirus of the Alphaherpesvirinae subfamily. Based on these results, GrHV-1 can be more accurately classified and diagnostic tools to investigate suspected cases of IBDC can be developed. Furthermore, GrHV-1 showed effective replication in primary cultured cells derived from duck and chicken embryos and embryo tissues, highlighting the importance of further studies to evaluate its interspecies transmission.

DOI： 10.1155/tbed/2658800

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Porcine reproductive and respiratory syndrome (PRRS), which is caused by the porcine reproductive and respiratory syndrome virus (PRRSV), has a significant impact on the global pork industry. It results in reproductive failure in sows and respiratory issues in pigs of all ages. Despite the availability of vaccines, controlling the PRRSV remains challenging, partly owing to the limitations of cell culture systems. Current methods largely rely on primary porcine alveolar macrophages (PAMs), which must be harvested from piglets and have limited proliferative capacity. Although some simian cell lines support PRRSV replication, their inability to express porcine CD163, which is a key receptor for PRRSV entry, compromises their effectiveness, because the virus replicates differently in these non-target cells. To address these issues, we established an immortalized PAM cell line, PAM-T43, using SV40 large T antigen for immortalization and porcine serum as a culture supplement. PAM-T43 cells maintain essential macrophage functions, including CD163 expression and phagocytic activity, and exhibit high sensitivity to the PRRSV, efficiently supporting viral replication. This novel cell line offers significant potential for advancing PRRSV research, particularly in vaccine development and field strain isolation, by overcoming the limitations of current systems.

DOI： 10.3390/pathogens13121026

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Language：Japanese   Publisher：Kitakyushu Museum of Natural History and Human History  

<p>There has so far been no record of the Endo’s pipistrelle, <i>Pipistrellus endoi </i>Imaizumi, 1959, in Fukuoka Prefecture. We performed a capturing survey using mist nets in Yakushi-toge, Soeda-machi, Fukuoka Prefecture in March and June 2023. One adult male was captured on 11 June and was kept as a voucher specimen. External and skull measurement values were similar to those of <i>P. endoi</i>. The shape of the baculum of the specimen was similar to that of <i>P. endoi</i>, and its length was 9 mm. Based on these results, the specimen was finally identified as <i>P. endoi</i>. Mitochondrial <i>CO1</i> sequences were almost identical to those of <i>P. endoi</i> in Kumamoto Prefecture. The peak frequency and duration of echolocation calls averaged 62.3 kHz and 2.4 ms, and those of the search phase averaged 41.0 kHz and 4.9 ms, respectively.</p>

DOI： 10.34522/kmnh.22.0_36

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

Avian influenza (AI) is an extremely contagious viral disease of domestic and wild birds that can spread rapidly among bird populations, inducing serious economic losses in the poultry industry. During the winter season 2021-2022, we isolated seventeen highly pathogenic avian influenza (HPAI) H5N8 viruses from outbreaks involving ducks in Egypt, occurring in both backyard and farm settings. The aim of this study was to pinpoint genetic key substitutions (KSs) that could heighten the risk of a human pandemic by influencing the virus's virulence, replication ability, host specificity, susceptibility to drugs, or transmissibility. To understand their evolution, origin, and potential risks for a human pandemic, whole-genome sequencing and phylogenetic analysis were conducted. Our analysis identified numerous distinctive mutations in the Egyptian H5N8 viruses, suggesting potential enhancements in virulence, resistance to antiviral drugs, and facilitation of transmission in mammals. In this study, at least five genotypes within one genome constellation of H5N8 viruses were identified, raising concerns about the potential emergence of novel viruses with altered characteristics through reassortment between different genotypes and distinct groups. These findings underscore the role of ducks in the virus's evolutionary process and emphasize the urgent need for enhanced biosecurity measures in domestic duck farms to mitigate pandemic risk.

DOI： 10.3390/v16111655

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Language：Japanese   Publishing type：Research paper (scientific journal)  

We isolated highly pathogenic avian influenza (HPAI) H5N5 and H5N1 viruses from crows in Hokkaido, Japan, during winter 2023-24. They shared genetic similarity with HPAI H5N5 viruses from northern Europe but differed from those in Asia. Continuous monitoring and rapid information sharing between countries are needed to prevent HPAI virus transmission.

DOI： 10.3201/eid3009.240356

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Language：Japanese   Publishing type：Research paper (scientific journal)  

In the 2021/22 winter, one H5N1 and nine H5N8 high pathogenicity avian influenza viruses (HPAIVs) of clade 2.3.3.4b were isolated from the water in crane roosts on the Izumi plain, Japan. Additionally, we isolated low pathogenicity avian influenza viruses (LPAIVs) of five subtypes: H1N1, H4N2, H4N6, H7N7, and H10N4. H5N8 HPAIVs belonging to the G2a group were isolated throughout winter, whereas H5N1 HPAIV belonging to the G2b group were isolated only in early winter. These findings suggest co-circulation of both G2a and G2b HPAIVs in early winter. Although two H7N7 LPAIVs were isolated from cranes' roost water collected on the same day, the gene constellations of the two isolates were clearly different, indicating the contemporary invasion of at least two different genotypes of H7N7 LPAIVs in the Izumi plain. This study underscores the importance of monitoring both HPAIVs and LPAIVs to understand avian influenza virus ecology in migratory waterfowl populations.

DOI： 10.1016/j.cimid.2024.102182

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Bats represent natural reservoirs of several paramyxoviruses, raising concerns about the potential for these viruses to cause cross-species infections. In this study, we isolated two jeilongviruses belonging to the family Paramyxoviridae from oral swab samples of the Eastern bent-wing bat (Miniopterus fuliginosus) and Far Eastern myotis bat (Myotis bombinus) in Kagoshima Prefecture, Japan. Notably, this is the first report isolating bat paramyxoviruses in Japan. Genomic analyses revealed a high identity between Kagoshima isolates (PMV/Bat35 and PMV/Bat111) and jeilongvirus B16-40, previously isolated from a Schreiber's bent-wing bat (Miniopterus schreibersii) in South Korea in 2016. PMV/Bat35 infected and replicated in a range of cell lines derived from different animal species, although the level of syncytium formation varied among cell lines. Animal experiments revealed that Syrian hamsters inoculated intranasally with PMV/Bat35 did not exhibit clinical symptoms or significant weight loss. Nevertheless, viral genes were detected in the lungs and tracheas of Syrian hamsters on 2- and 5-day postinfection (dpi). Importantly, neutralizing antibodies against PMV/Bat35 developed in hamsters on 14 dpi. These results suggest that bat jeilongviruses can cross the species barriers. Our findings highlight the critical importance of ongoing monitoring and characterization of viruses circulating in bat populations to assess the risk of zoonotic outbreaks.

DOI： 10.1155/TBED/5530007

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Highly pathogenic avian influenza viruses (HPAIVs) have caused outbreaks in both domestic and wild birds during the winter seasons in several countries in the Northern Hemisphere, most likely because virus-infected wild ducks overwinter and serve as the primary source of infection for other birds in these countries. Several chemical disinfectants are available to deactivate these viruses outside a living organism. However, their virucidal activity is known to be compromised by various factors, including temperature and contamination with organic matter. Hence, the effectiveness of virucidal activity under winter field conditions is crucial for managing HPAIV outbreaks. To investigate the impact of the winter field conditions on the virucidal activity of disinfectants against AIVs, we assessed the stability of the virucidal activity of seven representative disinfectants that are commercially available for poultry farms in Japan against both LPAIVs and HPAIVs under cold and/or organic contamination conditions. Of the seven disinfectants examined, the ortho-dichlorobenzene/cresol-based disinfectant exhibited the most consistent virucidal activity under winter field conditions, regardless of the virus pathogenicity or subtype tested.

DOI： 10.3390/pathogens12121382

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Newcastle disease caused by highly pathogenic viruses of avian paramyxovirus serotype-1 (APMV-1) is a highly contagious poultry disease. Although a large-scale epidemic of Newcastle disease had occurred in Japan between the 1950s and the 2000s, there have been no outbreaks anywhere since 2010. In addition, there are no reports of epidemiological surveys of APMV-1 in wild birds in Japan in the last 10 years. We conducted the first epidemiological survey of APMV-1 in the Izumi plain, Kagoshima prefecture of southern Japan from the winter of 2018 to 2022. A total of 15 APMV-1 strains were isolated, and isolation rates from roosting water and duck fecal samples were 2.51% and 0.10%, respectively. These results indicate that the isolation method from environmental water may be useful for efficient surveillance of APMV-1 in wild birds. Furthermore, this is the first report on the success of APMV-1 isolation from environmental water samples. Genetic analysis of the Fusion (F) gene showed that all APMV-1 isolates were closely related to virus strains circulating among waterfowl in Far East Asian countries. All isolates have avirulent motifs in their cleavage site of F genes, all of which were presumed to be low pathogenic viruses in poultry. However, pathogenicity test using embryonated chicken eggs demonstrated that some isolates killed all chicken embryos regardless of viral doses inoculated (102 -106 50% egg infectious dose). These results indicated that APMV-1 strains, which are potentially pathogenic to chickens, are continuously brought into the Izumi plain by migrating wild birds.

DOI： 10.1111/1348-0421.13053

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Language：Japanese   Publishing type：Research paper (scientific journal)  

During the 2020/21 winter season, 29 and 10 H5N8 high pathogenicity avian influenza viruses (HPAIVs) were isolated from environmental water and wild birds, respectively, in Kagoshima prefecture, Japan. Furthermore, seven subtypes of low pathogenicity avian influenza viruses (LPAIVs) were also isolated; H1N1, H2N9, H3N2, H3N6, H3N8, H4N6, and H6N6 subtypes. While the H5 hemagglutinin (HA) genes of the G1 cluster were isolated throughout the winter season, those of the G2 cluster were also detected in late winter, suggesting that H5 HPAIVs possessing H5 HA genes from the two different clusters were individually introduced into Kagoshima prefecture. Intriguingly, genetic constellations revealed that the H5N8 HPAIVs could be classified into six genotypes, including four previously reported genotypes (E1, E2, E3, and E7), and two new genotypes (tentatively named E8 and E9). The PB1 and PA gene segments of genotypes E8 and E9 shared high similarity with those of LPAIVs, whereas the remaining gene segments were close to those of genotype E1. Furthermore, LPAIVs whose PA gene segment was close to that of genotype E9 were isolated from the environmental water. Overall, we revealed that various HPAIV genotypes circulated in Kagoshima prefecture during the 2020/21 winter season. This study highlights the importance of monitoring both HPAIV and LPAIV to better understand AIV ecology in migratory waterfowl populations.

DOI： 10.1099/jgv.0.001870

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Language：Japanese   Publishing type：Research paper (scientific journal)  

The Izumi plain in the Kagoshima Prefecture, Japan, is known as an overwintering site for more than 30,000 migratory waterfowl, including endangered crane species. We previously reported that environmental water samples, from artificial wet paddies created as crane roost sites on the Izumi plain, are useful for avian influenza virus (AIV) surveillance. During the 2019/20 winter season, we collected 238 water samples from the crane roost sites and isolated 22 AIVs of six subtypes: one H1N1, one H3N2, seven H3N8, four H4N6, nine H6N6, and one H11N2 subtypes. Genetic analyses revealed that AIVs of the same subtype isolated from the Izumi plain during a single winter season exhibited multiple genetic constellations. Furthermore, phylogenetic analyses suggested that our H3N2 isolate may be a genetic reassortant between close relatives to our H3N8 and H11N2 isolates. Our study highlighted the importance of monitoring AIV circulation to better understand AIV ecology in migratory waterfowl populations.

DOI： 10.3390/pathogens11091013

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Crane-associated adenovirus 1 (CrAdV-1) is a proposed novel virus in the genus Aviadenovirus, first detected in faecal samples from hooded cranes (a vulnerable crane species) on the Izumi plain, a major overwintering site for migratory cranes in Japan. CrAdV-1 was genetically characterized in that study; however, its virological characteristics remain largely unclear. To investigate the prevalence and organ tropism of CrAdV-1, we collected swab and organ samples from dead or debilitated cranes on the Izumi plain. CrAdV-1 gene was detected in 47% (45/95) of tested cranes, comprising mainly hooded cranes but also white-naped and sandhill cranes. These results indicate that CrAdV-1 shedding is widespread among cranes overwintering on the Izumi plain. Phylogenetic analyses revealed that the 68 nucleotide sequences determined from the positive swabs formed a single cluster, suggesting phylogenetic differences between CrAdV-1 and other aviadenoviruses. CrAdV-1 prevalence showed a significant linear increase with time through the overwintering period (November to February), especially among juveniles. These findings indicate that CrAdV-1 spreads mainly by transmission between juveniles progressively through the overwintering period. The CrAdV-1 gene-positive rate was significantly higher in cloacal swabs than conjunctival or tracheal swabs. Copy numbers for the partial CrAdV-1 gene sequence were markedly high in the colon samples from three of the four cranes investigated for organ tropism. We also detected relatively high copy numbers in the cerebrum, trachea, lung and heart, suggesting that CrAdV-1 mainly targets these four organs and transmitted via the faecal-oral route and airborne transmission. These results contribute to further understanding of the virological characteristics of CrAdV-1.

DOI： 10.1111/tbed.14631

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Genetic analyses of highly pathogenic avian influenza H5 subtype viruses isolated from the Izumi Plain, Japan, revealed cocirculation of 2 genetic groups of clade 2.3.4.4b viruses among migratory waterfowl. Our findings demonstrate that both continuous surveillance and timely information sharing of avian influenza viruses are valuable for rapid risk assessment.

DOI： 10.3201/eid2807.212586

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Recent global outbreaks of highly pathogenic avian influenza viruses (HPAIVs) of the H5N8 subtype in poultry and wild birds have raised concerns about animal and human health, particularly after its first evidence of zoonotic transmission from birds to humans. Here, we report a lethal infection with the H5N8 HPAIV in a mandarin duck that had previously demonstrated resistance to the H5N8 HPAIV infection. In addition, we revealed that the isolated virus was a genetic reassortant between the existing H5N8 HPAIV and LPAIV(s). Although further studies are warranted to assess the impact of the genetic reassortment on virus pathogenicity, the potential role of mandarin ducks in HPAIV dissemination should be re-evaluated.

DOI： 10.3390/zoonoticdis2010004

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Language：Japanese   Publisher：The Mammal Society of Japan  

<p>To date, Endo’s pipistrelle (<i>Pipistrellus endoi</i>) had not been recorded, in Kyushu District. To confirm the bat fauna, particularly whether <i>P. endoi</i> occurred, we performed a capture survey using mist nets in Yamaemura, Kumamoto Prefecture, in August 2021. Two bats were captured, one of which was identified as <i>Myotis macrodactylus</i>. The other bat which could not be identified was used as a specimen, which was considered to be either <i>P. abramus</i> or <i>P. endoi</i>. Measurements showed that the tragus of the specimen was wider than that of <i>P. abramus</i>. The upper first incisor was significantly longer than the upper second incisor. The upper second premolar of the specimen was larger than that of <i>P. abramus</i>, and the lower canine was smaller than that of <i>P. abramus</i>. The skull measurements of the specimen were the same as those of <i>P. endoi</i> in Honshu. The shape of the baculum of the specimen was similar to that of <i>P. endoi</i> in Honshu, and the length of the baculum was 9 mm, which was shorter than that of <i>P. abramus</i>. On the basis of these results, the specimen was identified as <i>P. endoi</i>. The results of principal component analysis for the 15 skull measurements of both species, including the present specimen, also indicated that the specimen was within the range of <i>P. endoi</i>, and skull shapes differed between the two species. Furthermore, phylogenetic analyses based on mitochondrial <i>CO1</i> sequences showed that the specimen belonged to a different genetic lineage than <i>P. abramus</i>.</p>

DOI： 10.11238/mammalianscience.62.239

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

We isolated two highly pathogenic avian influenza viruses (HPAIVs) of subtype H5N8 clade 2.3.4.4b from falcated duck (Anas falcata) feces and environmental water collected at an overwintering site in Japan. Our isolates were almost genetically identical to each other and showed high genetic similarity with H5N8 HPAIVs recently isolated in South Korea, a distant part of Japan, and European countries. These results suggest the potential role of falcated ducks in the dissemination of HPAIVs.

DOI： 10.3390/pathogens10020171

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Event date： 2025.6

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Event date： 2022.9

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Event date： 2022.9

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Event date： 2021.9

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Language：English   Presentation type：Poster presentation