Long-term immune responses induced by low-dose infection with high pathogenicity avian influenza viruses can protect mallards from reinfection with a heterologous strain.

Migratory water birds are considered to be carriers of high pathogenicity avian influenza viruses (HPAIVs). In Japan, mallards are often observed during winter, and HPAIV-infected mallards often shed viruses asymptomatically. In this study, we focused on mallards as potential carriers of HPAIVs and investigated whether individual wild mallards are repeatedly infected with HPAIVs and act as HPAIV carriers multiple times within a season.

Phylogenetic and Pathogenic Analysis of H5N1 and H5N6 High Pathogenicity Avian Influenza Virus Isolated from Poultry Farms (Layer and Broiler Chickens) in Japan in the 2023/2024 Season.

During the 2023-2024 winter, 11 high pathogenicity avian influenza (HPAI) outbreaks caused by clade 2.3.4.

Genetic diversity of H5N1 and H5N2 high pathogenicity avian influenza viruses isolated from poultry in Japan during the winter of 2022-2023.

High pathogenicity avian influenza viruses (HPAIVs) of the H5N1 and H5N2 subtypes were responsible for 84 HPAI outbreaks on poultry premises in Japan during October 2022-April 2023. The number of outbreaks during the winter of 2022-2023 is the largest ever reported in Japan. In this study, we performed phylogenetic analyses using the full genetic sequences of HPAIVs isolated in Japan during 2022-2023 and those obtained from a public database to identify their genetic origin.

Genetics of H5N1 and H5N8 High-Pathogenicity Avian Influenza Viruses Isolated in Japan in Winter 2021-2022.

In winter 2021-2022, H5N1 and H5N8 high-pathogenicity avian influenza (HPAI) viruses (HPAIVs) caused serious outbreaks in Japan: 25 outbreaks of HPAI at poultry farms and 107 cases in wild birds or in the environment. Phylogenetic analyses divided H5 HPAIVs isolated in Japan in the winter of 2021-2022 into three groups-G2a, G2b, and G2d-which were disseminated at different locations and times. Full-genome sequencing analyses of these HPAIVs revealed a strong relationship of multiple genes between Japan and Siberia, suggesting that they arose from reassortment events with avian influenza viruses (AIVs) in Siberia.

Experimental Infection of Chickens with H5N8 High Pathogenicity Avian Influenza Viruses Isolated in Japan in the Winter of 2020-2021.

During the winter of 2020-2021, numerous outbreaks of high pathogenicity avian influenza (HPAI) were caused by viruses of the subtype H5N8 in poultry over a wide region in Japan. The virus can be divided into five genotypes-E1, E2, E3, E5, and E7. The major genotype responsible for the outbreaks was E3, followed by E2.

Detection of H5N1 High Pathogenicity Avian Influenza Viruses in Four Raptors and Two Geese in Japan in the Fall of 2022.

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.

Different Infectivity and Transmissibility of H5N8 and H5N1 High Pathogenicity Avian Influenza Viruses Isolated from Chickens in Japan in the 2021/2022 Season.

H5N8 and H5N1 high pathogenicity avian influenza viruses (HPAIVs) caused outbreaks in poultry farms in Japan from November 2021 to May 2022. Hemagglutinin genes of these viruses belong to clade 2.3.

Genetically Diverse Highly Pathogenic Avian Influenza A(H5N1/H5N8) Viruses among Wild Waterfowl and Domestic Poultry, Japan, 2021.

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.

Multiple Routes of Antibody-Dependent Enhancement of SARS-CoV-2 Infection.

Antibody-dependent enhancement (ADE) of infection is generally known for many viruses. A potential risk of ADE in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has also been discussed since the beginning of the coronavirus disease 2019 (COVID-19) pandemic; however, clinical evidence of the presence of antibodies with ADE potential is limited. Here, we show that ADE antibodies are produced by SARS-CoV-2 infection and the ADE process can be mediated by at least two different host factors, Fcγ receptor (FcγR) and complement component C1q.

Structural Insights into the Interaction of Filovirus Glycoproteins with the Endosomal Receptor Niemann-Pick C1: A Computational Study.

Filoviruses, including marburgviruses and ebolaviruses, have a single transmembrane glycoprotein (GP) that facilitates their entry into cells. During entry, GP needs to be cleaved by host proteases to expose the receptor-binding site that binds to the endosomal receptor Niemann-Pick C1 (NPC1) protein. The crystal structure analysis of the cleaved GP (GPcl) of Ebola virus (EBOV) in complex with human NPC1 has demonstrated that NPC1 has two protruding loops (loops 1 and 2), which engage a hydrophobic pocket on the head of EBOV GPcl.

Receptor-Mediated Host Cell Preference of a Bat-Derived Filovirus, Lloviu Virus.

Lloviu virus (LLOV), a bat-derived filovirus that is phylogenetically distinct from human pathogenic filoviruses such as Ebola virus (EBOV) and Marburg virus (MARV), was discovered in Europe. However, since infectious LLOV has never been isolated, the biological properties of this virus remain poorly understood. We found that vesicular stomatitis virus (VSV) pseudotyped with the glycoprotein (GP) of LLOV (VSV-LLOV) showed higher infectivity in one bat ( sp.

A Surrogate Animal Model for Screening of Ebola and Marburg Glycoprotein-Targeting Drugs Using Pseudotyped Vesicular Stomatitis Viruses.

Filoviruses, including Ebola virus (EBOV) and Marburg virus (MARV), cause severe hemorrhagic fever in humans and nonhuman primates with high mortality rates. There is no approved therapy against these deadly viruses. Antiviral drug development has been hampered by the requirement of a biosafety level (BSL)-4 facility to handle infectious EBOV and MARV because of their high pathogenicity to humans.

Genetic and antigenic characterization of H5 and H7 avian influenza viruses isolated from migratory waterfowl in Mongolia from 2017 to 2019.

The circulation of highly pathogenic avian influenza viruses (HPAIVs) of various subtypes (e.g., H5N1, H5N6, H5N8, and H7N9) in poultry remains a global concern for animal and public health.

Niemann-Pick C1 Heterogeneity of Bat Cells Controls Filovirus Tropism.

Fruit bats are suspected to be natural hosts of filoviruses, including Ebola virus (EBOV) and Marburg virus (MARV). Interestingly, however, previous studies suggest that these viruses have different tropisms depending on the bat species. Here, we show a molecular basis underlying the host-range restriction of filoviruses.

Molecular characterization and phylogenetic analysis of spp. detected from striped leaf-nosed bats () in Zambia.

Bat trypanosomes consist of more than 30 trypanosome species from over 70 species of bats. Recent studies suggest that bats play a role in disseminating trypanosomes from African continent to the terrestrial mammals both in the Afrotropic-Palearctic Ecozones and Nearctic Ecozone. However, the diversity, distribution, and evolution of bat trypanosomes are still unclear.

Generation of bat-derived influenza viruses and their reassortants.

Two novel influenza A virus-like genomes were detected in fruit bats in Central and South America. However, the biological properties of these bat-derived influenza viruses (BatIVs) are still largely unknown since infectious viral particles have never been isolated from the infected host species. In this study, a reverse genetics approach was used to generate infectious BatIV particles entirely from plasmids encoding full-length sequences in eight gene segments.

Single-Nucleotide Polymorphisms in Human NPC1 Influence Filovirus Entry Into Cells.

Niemann-Pick C1 (NPC1), a host receptor involved in the envelope glycoprotein (GP)-mediated entry of filoviruses into cells, is believed to be a major determinant of cell susceptibility to filovirus infection. It is known that proteolytically digested Ebola virus (EBOV) GP interacts with 2 protruding loops in domain C of NPC1. Using previously published structural data and the National Center for Biotechnology Information Single-Nucleotide Polymorphism (SNP) database, we identified 10 naturally occurring missense SNPs in human NPC1.

Seroprevalence of Filovirus Infection of Rousettus aegyptiacus Bats in Zambia.

Bats are suspected to play important roles in the ecology of filoviruses, including ebolaviruses and marburgviruses. A cave-dwelling fruit bat, Rousettus aegyptiacus, has been shown to be a reservoir of marburgviruses. Using an enzyme-linked immunosorbent assay with the viral glycoprotein antigen, we detected immunoglobulin G antibodies specific to multiple filoviruses in 158 of 290 serum samples of R aegyptiacus bats captured in Zambia during the years 2014-2017.

Genetic characterization of feline bocavirus detected in cats in Japan.

Feline bocavirus (FBoV) has been classified into three genotypes (FBoV1-FBoV3). FBoVs are mainly detected in feces. In the present study, we collected rectal swabs from cats in Japan and examined the samples for the presence of FBoV.