Genome-sequence analysis of the pathogenic H5N1 avian influenza A virus isolated in China in 2004.

Analysis of the sequences of the genome of the avian influenza A/chicken/Hubei/327/2004 (H5N1) virus, isolated from a poultry farm during the outbreak of avian influenza (AI) in Hubei Province, central China, in the spring of 2004, revealed that the hemagglutinin (HA) gene of the virus was genetically similar to those of the H5 highly pathogenic avian influenza virus (HPAI). Notably, the neuraminidase gene of the virus had a 20-amino acid deletion in the stalk region and a 5-amino acid deletion in the NS gene which belonged to allele B. Furthermore, the internal genes (PB2, PA, NP, M2) of the A/chicken/Hubei/327/2004 virus with the particular amino acid residues were more closely related to H5N1 viruses of 2000-2003 isolated in Hong Kong and the AIV of Thailand and Vietnam in 2004, but less likely to evolve from the viruses of Hong Kong 1997.