Isolation of ortho- and paramyxoviruses from feral birds in Hokkaido, Japan--1980 and 1981

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

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.

Antigenic variation of Newcastle disease viruses isolated from wild ducks in Japan

Nineteen strains of Newcastle disease virus (NDV) isolated from wild ducks in Japan were placed into 4 distinct antigenic groups on the basis of their reactivities to 8 monoclonal antibodies against the HN molecule of NDV in hemagglutination inhibition tests. The NDV strains of duck origin were antigenically distinct from NDV-B1 and NDV-Miyadera originated from chickens, and varied in their virulence to chicken embryos. No apparent correlation was found between the antigenicity of the HN molecule and virulence.

Antigenic and genetic conservation of H3 influenza virus in wild ducks

The hemagglutinins of H3 influenza viruses isolated from migratory ducks on the Pacific flyway in Japan during the period 1977 to 1985 were analyzed antigenically and genetically. Antigenic analysis using monoclonal antibodies to the hemagglutinins of A/Aichi/2/68 (H3N2) and A/duck/Hokkaido/8/80 (H3N8) viruses showed that antigenic drift occurred extensively in human strains, whereas the hemagglutinins of duck viruses were highly conserved. It was also found that the hemagglutinins of duck viruses were antigenically closely related to that of human 1968 H3 prototype strains. Nucleotide sequence analysis of seven duck H3 hemagglutinin genes showed a limited number of changes among the six duck isolates and between these duck isolates and Aichi/68. The deduced amino acid sequence revealed amino acid changes randomly distributed throughout the molecule and not confined to antigenic sites. These findings indicate that the duck virus hemagglutinin genes are conserved in nature and that viruses of different lineages cocirculate.

Pathogenicity and immunogenicity in chickens of Newcastle disease viruses isolated from wild ducks. Brief report

Three Newcastle disease viruses (NDV) isolated from wild ducks in Japan were evaluated for their biological activities, pathogenicity and immunogenicity against one-day-old chickens. One isolate was of the mesogenic type and the other two were of the lentogenic type for chicken. The lentogenic isolates could induce enough immunity in chickens to protect them from challenge with a virulent strain of NDV.

Contact infection of mink with 5 subtypes of avian influenza virus. Brief report

Avian influenza viruses of H3N8, H11N4, H7N7, H8N4, and H5N3 infected mink by contact.