Molecular characterization of avian influenza virus (H7N8) isolated from poultry in Central China in the mid-1980s

The molecular and pathogenic properties of avian influenza virus (A/duck/Hubei/216/1985/H7N8) isolated from Hubei Province of China in 1985 were characterized. The hemagglutinin gene (HA) of Dk/Hb/216/85/H7N8 had the multiple amino acid sequences (-PEIPKGRG-) at the connecting peptide between HA1 and HA2, which is considered to be a distinguishing molecular characteristic of low pathogenicity. The key sites of host markers among the genes (M, NP, NS, PA and PB2) of Dk/Hb/216/85/H7N8 were similar to those of H5N1 viruses. Phylogenetic analysis showed that the genes (M, NS and PB2) of Dk/Hb/216/85/H7N8 clustered closely with those of Gs/Guangdong/1996/H5N1 (Gs/GD/96), implying that three ancient genes of Gs/GD/96-like viruses had been circulating in Central China during the 1980s. In experimental infection, Dk/Hb/216/85/H7N8 was lowly pathogenic to chickens and mice, consistent with the molecular feature of HA gene.