Surveillance and characterization of avian influenza viruses from migratory water birds in eastern Hokkaido, the northern part of Japan, 2009–2010

A literature review of the use of environmental sampling in the surveillance of avian influenza viruses

This literature review provides an overview of use of environmental samples (ES) such as faeces, water, air, mud and swabs of surfaces in avian influenza (AI) surveillance programs, focussing on effectiveness, advantages and gaps in knowledge. ES have been used effectively for AI surveillance since the 1970s. Results from ES have enhanced understanding of the biology of AI viruses in wild birds and in markets, of links between human and avian influenza, provided early warning of viral incursions, allowed assessment of effectiveness of control and preventive measures, and assisted epidemiological studies in outbreaks, both avian and human. Variation exists in the methods and protocols used, and no internationally recognized guidelines exist on the use of ES and data management. Few studies have performed direct comparisons of ES versus live bird samples (LBS). Results reported so far demonstrate reliance on ES will not be sufficient to detect virus in all cases when it is present, especially when the prevalence of infection/contamination is low. Multiple sample types should be collected. In live bird markets, ES from processing/selling areas are more likely to test positive than samples from bird holding areas. When compared to LBS, ES is considered a cost-effective, simple, rapid, flexible, convenient and acceptable way of achieving surveillance objectives. As a non-invasive technique, it can minimize effects on animal welfare and trade in markets and reduce impacts on wild bird communities. Some limitations of environmental sampling methods have been identified, such as the loss of species-specific or information on the source of virus, and taxonomic-level analyses, unless additional methods are applied. Some studies employing ES have not provided detailed methods. In others, where ES and LBS are collected from the same site, positive results have not been assigned to specific sample types. These gaps should be remedied in future studies.

H9 Influenza Viruses: An Emerging Challenge

Influenza A viruses (IAVs) of the H9 subtype are enzootic in Asia, the Middle East, and parts of North and Central Africa, where they cause significant economic losses to the poultry industry. Of note, some strains of H9N2 viruses have been linked to zoonotic episodes of mild respiratory diseases. Because of the threat posed by H9N2 viruses to poultry and human health, these viruses are considered of pandemic concern by the World Health Organization (WHO). H9N2 IAVs continue to diversify into multiple antigenically and phylogenetically distinct lineages that can further promote the emergence of strains with pandemic potential. Somewhat neglected compared with the H5 and H7 subtypes, there are numerous indicators that H9N2 viruses could be involved directly or indirectly in the emergence of the next influenza pandemic. The goal of this work is to discuss the state of knowledge on H9N2 IAVs and to provide an update on the contemporary global situation.

Molecular characterization of Cryptosporidium spp. from migratory ducks around Tokachi subprefecture, Hokkaido, Japan

Cryptosporidium, a waterborne protozoan parasite, has a substantial veterinary and medical impact worldwide. This parasite is more often recognized during waterborne outbreaks because of its resistance to chlorine disinfection, small size making it difficult to inactivate/eliminate through filtration, and presence in many animal species including humans. Migratory waterfowl, in addition to acting as mechanical carriers of Cryptosporidium oocysts, can also serve as natural reservoirs of infection by host-specific Cryptosporidium species. For better understanding of the extent of genetic diversity and inter-relationships among avian isolates of Cryptosporidium, 200 fecal samples of migratory ducks from the Tokachi subprefecture, Hokkaido, Japan were collected and analyzed by nested PCR (N-PCR) at the 18S rRNA gene. N-PCR revealed that 11.5% (23/200) were positive for Cryptosporidium spp. Among all samples, sequence analysis identified that 10% (20/200) were 98-100% identical to Cryptosporidium avian genotype III. On the other hand, 1.5% (3/200) were 99-100% identical to C. baileyi. This is the first molecular study reporting the prevalence of Cryptosporidium in migratory ducks in Japan. Genetic diversity among Cryptosporidium isolates from humans and birds has been reported worldwide. Nevertheless, further studies are important to assess genetic variety and to elucidate the transmission dynamics of Cryptosporidium parasites.

Genetic characterization of an avian H4N6 influenza virus isolated from the Izumi plain, Japan

An influenza A virus of H4N6 subtype was isolated from the Izumi plain, Japan, in 2013. Genetic analyses revealed that two viral genes (M and NS gene segments) of this isolate were genetically distinct from those of the H4N6 virus isolated from the same place in 2012. Furthermore, three viral genes (PB2, PB1 and M gene segments) of this isolate share high similarity with those of the North American isolates of 2014. These results suggest a high frequency of genetic reassortment of avian influenza viruses in Asian waterfowl and intercontinental movements of avian influenza viruses via migratory waterfowl.

Five distinct reassortants of H5N6 highly pathogenic avian influenza A viruses affected Japan during the winter of 2016-2017

To elucidate the evolutionary pathway, we sequenced the entire genomes of 89 H5N6 highly pathogenic avian influenza viruses (HPAIVs) isolated in Japan during winter 2016-2017 and 117 AIV/HPAIVs isolated in Japan and Russia. Phylogenetic analysis showed that at least 5 distinct genotypes of H5N6 HPAIVs affected poultry and wild birds during that period. Japanese H5N6 isolates shared a common genetic ancestor in 6 of 8 genomic segments, and the PA and NS genes demonstrated 4 and 2 genetic origins, respectively. Six gene segments originated from a putative ancestral clade 2.3.4.4 H5N6 virus that was a possible genetic reassortant among Chinese clade 2.3.4.4 H5N6 HPAIVs. In addition, 2 NS clusters and a PA cluster in Japanese H5N6 HPAIVs originated from Chinese HPAIVs, whereas 3 distinct AIV-derived PA clusters were evident. These results suggest that migratory birds were important in the spread and genetic diversification of clade 2.3.4.4 H5 HPAIVs.

Characterization of avian paramyxovirus serotype 14, a novel serotype, isolated from a duck fecal sample in Japan

A hemagglutinating virus isolate designated 11OG0352, was obtained from a duck fecal sample. Genetic and virological analyses indicated that it might represent a novel serotype of avian paramyxovirus (APMV). Electron micrographs showed that the morphology of the virus particle was similar to that of APMV. The complete genome of this virus comprised 15,444 nucleotides complying with the paramyxovirus "rule of six" and contains six open reading frames (3'-N-P-M-F-HN-L-5'). The phylogenetic analysis of the whole genome revealed that the virus was a member of the genus Avulavirus, but that it was distinct from APMV-1 to APMV-13. Although the F-protein cleavage site was TREGK↓L, which resembles a lentogenic strain of APMV-1, the K residue at position -1 of the cleavage site was first discovered in APMV members. The phosphoprotein gene of isolate 11OG0352 contains a putative RNA editing site, 3'-AUUUUCCC-5' (negative sense) which sequence differs from that of other APMVs. The intracerebral pathogenicity index test did not detect virulence in infected chicks. In hemagglutination inhibition (HI) tests, an antiserum against this virus did not detectably react with other APMVs (serotypes 1-4, 6-9) except for low reciprocal cross-reactivity with APMV-6. We designated this isolate, as APMV-14/duck/Japan/11OG0352/2011 and propose that it is a novel APMV serotype. The HI test may not be widely applicable for the classification of a new serotype because of the limited availability of reference antisera against all serotypes and cross-reactivity data. The nucleotide sequence identities of the whole genome of 11OG0352 and other APMVs ranged from 46.3% to 56.1%. Such comparison may provide a useful tool for classifying new APMV isolates. However, the nucleotide sequence identity between APMV-12 and APMV-13 was higher (64%), which was nearly identical to the lowest nucleotide identity (67%) reported in subgroups within the serotype. Therefore, consensus criteria for using whole genome analysis should be established.

High antiviral effects of hibiscus tea extract on the H5 subtypes of low and highly pathogenic avian influenza viruses

Viral neuraminidase inhibitors are widely used as synthetic anti-influenza drugs for the prevention and treatment of influenza. However, drug-resistant influenza A virus variants, including H5N1 highly pathogenic avian influenza viruses (HPAIVs), have been reported. Therefore, the discovery of novel and effective antiviral agents is warranted. We screened the antiviral effects of 11 herbal tea extracts (hibiscus, black tea, tencha, rosehip tea, burdock tea, green tea, jasmine tea, ginger tea, lavender tea, rose tea and oak tea) against the H5N1 HPAIV in vitro. Among the tested extracts, only the hibiscus extract and its fractionated extract (frHibis) highly and rapidly reduced the titers of all H5 HPAIVs and low pathogenic AIVs (LPAIVs) used in the pre-treatment tests of Madin–Darby canine kidney (MDCK) cells that were inoculated with a mixture of the virus and the extract. Immunogold electron microscopy showed that anti-H5 monoclonal antibodies could not bind to the deformed H5 virus particles pretreated with frHibis. In post-treatment tests of MDCK cells cultured in the presence of frHibis after infection with H5N1 HPAIV, the frHibis inhibited viral replication and the expression of viral antigens and genes. Among the plants tested, hibiscus showed the most prominent antiviral effects against both H5 HPAIV and LPAIV.

Genetic characterization of a rare H12N3 avian influenza virus isolated from a green-winged teal in Japan

This study reports on the genetic characterization of an avian influenza virus, subtype H12N3, isolated from an Eurasian green-winged teal (Anas crecca) in Japan in 2009. The entire genome sequence of the isolate was analyzed, and phylogenetic analyses were conducted to characterize the evolutionary history of the isolate. Phylogenetic analysis of the hemagglutinin and neuraminidase genes indicated that the virus belonged to the Eurasian-like avian lineage. Molecular dating indicated that this H12 virus is likely a multiple reassortant influenza A virus. This is the first reported characterization of influenza A virus subtype H12N3 isolated in Japan and these data contribute to the accumulation of knowledge on the genetic diversity and generation of novel influenza A viruses.

Complete genome sequence of a natural reassortant H9N2 avian influenza virus found in bean goose (Anser fabalis): direct evidence for virus exchange between Korea and China via wild birds

In 2011, we isolated a natural recombinant H9N2 avian influenza virus from fecal droppings of bean goose (Anser fabalis) in Korea. Phylogenetic analyses showed that the A/bean goose/Korea/220/2011(H9N2) isolate is a reassortant of Eurasian and North American lineages of avian influenza virus. In addition, the complete genome sequence, including all 8 gene segments, was associated with Chinese H9N2 viruses isolated from wild birds in the Hunan East Dongting Lake National Nature Reserve. These data provide direct evidence for the exchange of avian influenza viruses between Korea and China via wild birds.