Genetic analyses of avian influenza viruses in Mongolia, 2007 to 2009, and their relationships with Korean isolates from domestic poultry and wild birds.

The present study was conducted to monitor wild birds based on the concern that they could disseminate avian influenza virus (AIV) between Mongolia and Korea, which shares the same migratory flyway. Of 1,528 fecal samples analyzed, 21 low-pathogenic AIV were isolated from 2007 to 2009. Nineteen AIV-positive fecal samples were identified as Anseriformes by DNA bar coding. The most frequently isolated subtype was H3 (61.9%), and the most prevalent hemagglutinin/neuraminidase combination was H3N8 (52.4%). Phylogenetic analysis was performed to assess their genetic relationships with those of domestic poultry and wild birds in Korea. The H3 and H7 surface genes belonged to the Eurasian lineage and clustered together in a group with Korean wild birds and poultry. Most N8 genes clustered phylogenetically with viruses isolated in Eurasia, whereas 1 of the Mongolian viruses and some Korean viruses belonged to the North American lineage. The polymerase acidic protein of the internal gene was not distinguishable from the H5N1 highly pathogenic AIV of the goose/Guangdong/1/1996 (Gs/Gd)-like virus. Our study suggests that Mongolian AIV isolates have evolved with genetically multiple genotypes and are closely related to those of AIV in poultry as well as in wild birds in Korea.

Use of a baculovirus-expressed structural protein for the detection of antibodies to foot-and-mouth disease virus type A by a blocking enzyme-linked immunosorbent assay.

A blocking enzyme-linked immunosorbent assay (ELISA) with a baculovirus-expressed structural protein was developed for the detection of antibodies to foot-and-mouth disease virus type A. It exhibited 99% specificity with a cutoff of 53% inhibition. Its sensitivity was comparable to the sensitivities of the virus neutralization test and the liquid-phase blocking ELISA, indicating its potential as an alternative assay.

A description of two outbreaks of capripoxvirus disease in Mongolia.

Mongolia had no reported cases of capripoxvirus disease from 1977 until an outbreak of sheeppox in 2006-2007 and then goatpox in 2008. The two outbreaks occurred in geographically distant areas of Mongolia and, most strikingly, were highly species-specific. The 2006-2007 sheeppox outbreak affected no goats and the 2008 goatpox outbreak affected no sheep despite communal herding. The diseases were diagnosed using the polymerase chain reaction and virus neutralisation test. The P32 gene of the Mongolian sheeppox and goatpox viruses from the recent outbreaks were sequenced and compared with an archived 1967 strain of Goatpox virus from Mongolia. The P32 gene of the 2006-2007 Mongolian Sheeppox virus strain was identical to previously published sheeppox strains. The P32 gene of the 2008 Mongolian Goatpox virus strain was identical to the gene from virus isolated from recent goatpox outbreaks in China and Vietnam. The archived Mongolian Goatpox virus strain was unique.

Evidence of recombination in a new isolate of foot-and-mouth disease virus serotype Asia 1.

Phylogenetic analysis of the nucleotide sequence of VP1 revealed that a new isolate of foot-and-mouth disease virus (FMDV) serotype Asia 1 identified in Mongolia in 2005 was related to Chinese and Russian strains isolated during the same year. In this study, these strains were defined as East Asian strains having a common geographical origin, and the complete genomic sequence of the Mongolian strain (As1/MOG/05) was determined and compared to other strains of serotype Asia 1. As1/MOG/05 showed 100% identity with an East Asian strain from China (As1/Qinghai/CHA/05) in terms of its VP1 nucleotide sequence. However, the Mongolian strain has a four-amino acid extension in 3D that is missing from all other strains of serotype Asia 1, and which is not due to an insertion. A full genomic scan revealed that the Mongolian strain is closer to the East Asian strain As1/JS/CHA/05 than to all other strains of serotype Asia 1 in nearly all genomic regions. Within the narrow region of low similarity between the two sequences, As1/JS/CHA/05 was found to have a mosaic structure with a partial 2C fragment supposedly transferred from Hong Kong strain As1/HNK/CHA/05. The genomic mosaicism and extension detected in non-structural protein-coding regions in this study may be used to trace the origins and evolution of problematic strains of serotype Asia 1 that have arisen in East Asia since 2005.

Pathogenicity and vaccine efficacy of different clades of Asian H5N1 avian influenza A viruses in domestic ducks.

Waterfowl represent the natural reservoir of all subtypes of influenza A viruses, including H5N1. Ducks are especially considered major contributors to the spread of H5N1 influenza A viruses because they exhibit diversity in morbidity and mortality. Therefore, as a preventive strategy against endemic as well as pandemic influenza, it is important to reduce the spread of H5N1 influenza A viruses in duck populations. Here, we describe the pathogenicity of dominant clades (clades 1 and 2) of H5N1 influenza A viruses circulating in birds in Asia. Four representatives of dominant clades of the viruses cause symptomatic infection but lead to different profiles of lethality in domestic ducks. We also demonstrate the efficacy, cross-protectiveness, and immunogenicity of three different inactivated oil emulsion whole-virus H5 influenza vaccines (derived by implementing reverse genetics) to the viruses in domestic ducks. A single dose of the vaccines containing 1 mug of hemagglutinin protein provides complete protection against a lethal A/Duck/Laos/25/06 (H5N1) influenza virus challenge, with no evidence of morbidity, mortality, or shedding of the challenge virus. Moreover, two of the three vaccines achieved complete cross-clade or cross-subclade protection against the heterologous avian influenza virus challenge. Interestingly, the vaccines induce low or undetectable titers of hemagglutination inhibition (HI), cross-HI, and/or virus neutralization antibodies. The mechanism of complete protection in the absence of detectable antibody responses remains an open question.