Molecular Epidemiological Studies On H5N1 Influenza Viruses From Poultry In Nanning

Objective: The outbreak and wide spread of H5N1 influenza virus in Southeastern Asia and continuing interspecies transmission into humans make World Health Organization (WHO) believe that this virus became the most likely candidate for the next human pandemic influenza. To better understand the genesis and evolution of this virus, an influenza surveillance study was carried out at Nanning live-poultry markets. The information generated in this study is helpful for further understanding the avian influenza prevalence and recognizing the possible interspecies transmission.Methods: Virus isolation was routinely performed in embryonated chicken's eggs. Hemagglutination test (HA test) was used to screen out the positive virus and to decide the virus titer. Hemagglutination inhibition test (HI test), neuraminidase inhibition test (Nl test) and RT-PCR reactions were used to subtype all virus isolates. 16 representative H5N1 influenza viruses were partially sequenced for each of their eight gene segments. We genetically analysed and compared them with the viruses from Hong Kong, Southeastern Asia and Guangdong. Nucleotide homology analysis was conducted and phylogenetic trees were generated to understand the characteristic of Guangxi viruses and their relationship with viruses from Hong Kong, Southeastern Asia and Guangdong in genetics. Results: In total, 202 strains of influenza virus were isolated from 2463 swabs.