Characterization of H5N6 highly pathogenic avian influenza viruses isolated from wild and captive birds in the winter season of 2016 –2017 in northern Japan

ABSTRACT On November 15, 2016, a suspected case of highly pathogenic avian influenza (HPAI) in a dead black swan was reported from a zoo in Akita prefecture, northern Japan, and an HPAI virus (HPAIV) belonging to the H5N6 subtype was isolated from specimens taken from the bird. After the initial report, 230 cases of HPAI caused by H5N6 viruses were reported from wild birds, captive birds, and domestic poultry farms throughout the country during the winter season. In the present study, we further characterized 66 H5N6 HPAIVs isolated from northern Japan. Phylogenetic analysis of the hemagglutinin gene showed that the H5N6 viruses isolated in northern Japan clustered into Group C of Clade 2.3.4.4 together with other isolates collected in Japan, Korea, and Taiwan during the winter season of 2016–2017. The antigenicity of the Japanese H5N6 isolate differed slightly from that of HPAIVs isolated previously in Japan and China. The virus exhibited high pathogenicity and a high replication capacity in chickens, whereas virus growth was slightly lower in ducks compared with an H5N8 HPAIV isolate collected in Japan in 2014. Comprehensive analyses of Japanese isolates, including those from central, western, and southern Japan, as well as rapid publication of this information are essential to facilitate greater control of HPAIVs.
Source: Microbiology and Immunology - Category: Microbiology Authors: Tags: Original Article Source Type: research