Whole genomic sequence and pathogenicity analysis of a wild bird-derived H9N2 subtype avian influenza virus

To investigate the biological characteristics of a H9N2 subtype avian influenza virus(AIV) Wide Bird/Hu N/SC1400/2014(H9N2)(WB/400/14) that isolated from wild bird droppings collected in north of Hunan area, the whole genome of the isolate was sequenced and the pathogenicity of the isolate was evaluated in SPF chicken, SPF ducks and BALB/c mice.Sequence analysis showed that the isolate had a HA cleavage site of333 PAASDR ↓ GL340, which was identity to the sequence characters of low pathogenic AIV(LPAIV). The different gene segments of the isolate showed a complicated source, which had the high homology with H9, H6, H4, H1, H11, H10 and H3 subtype LPAIVs, respectively. The infectious experiments demonstrated that the isolate had no ability to duplicate in chicken and mice. However, the virus was able to be detected in partial organs of artificially infected ducks. In addition, the infected ducks were able to shed through throat and cloaca, while the contacting infected ducks only shed through cloaca, which illustrated that the isolate had the ability of horizontal transmission.