Highly pathogenic H5N6 influenza A viruses recovered from wild birds in Guangdong, southern China, 2014-2015

Abstract

Since 2013, highly pathogenic (HP) H5N6 influenza A viruses (IAVs) have emerged in poultry in Asia, especially Southeast Asia. These viruses have also caused sporadic infections in humans within the same geographic areas. Active IAV surveillance in wild birds sampled in Guangdong province, China from August 2014 through February 2015 resulted in the recovery of three H5N6 IAVs. These H5N6 IAV isolates possess the basic amino acid motif at the HA1-HA2 cleavage site that is associated with highly pathogenic IAVs infecting chickens. Noteworthy findings include: (1) the HP H5N6 IAV isolates were recovered from three species of apparently healthy wild birds (most other isolates of HP H5N6 IAV in Asia are recovered from dead wild birds or fecal samples in the environment) and (2) these isolates were apparently the first recoveries of HP H5N6 IAV for two of the three species thus expanding the demonstrated natural host range for these lineages of virus. This investigation provides additional insight into the natural history of HP H5N6 IAVs and identifies the occurrence of non-lethal, HP H5N6 IAV infections in wild birds thereby demonstrating the value of active IAV surveillance in wild birds.

Figure 1

Phylogenetic analyses of complete hemagglutinin (A) and PB2 (B) genes of indicated H5N6 viruses. Viruses highlighted in blue were characterized in this study. Human-isolated H5N6 are marked in red. Genotypes of the influenza viruses are shown on the right (A) as eight coloured blocks representing each gene segment (from left to right: PB2, PB1, polymerase acidic, haemagglutinin, nucleoprotein, neuraminidase, matrix and non-structural) with the colour indicating the lineage of that segment. Host species are: CK (chicken), DK (duck), GS (goose), PG (pigeon). Geographic locations are: ZJ (Zhejiang), GD (Guangdong), JX (Jiangxi), YN (Yunnan), DG (Dongguan), JS (Jiangsu), GZ (Guangzhou), Env (environment), SC (Sichuan), WZ (Wenzhou), SD (Shandong), SZ (Shenzhen), NC (Nanchang), WH (Wuhan), and HB (Hubei).