Epidemiology and Molecular Characterization of Highly Pathogenic H5N1 Avian Influenza Viruses Isolated from Backyard Poultry
Highly Pathogenic H5N1 influenza viruses have repeatedly caused serious outbreaks of disease in poultry since its first report in 1997. The disease is a major concern because of its economic impact on poultry industry due to high mortality and potential threat to human health. Outbreaks due to highly pathogenic avian influenza (HPAI) H5N1 virus were reported for the first time in India during 2006, in Jalgoan and Navapur areas of Maharashtra state. Three virus isolates of H5N1 obtained from the backyard poultry were used in this study for molecular characterization. To study the phylogenetic relationship of H5N1 virus isolates with other H5N1 viruses, world over, complete genome of all the eight RNA segments were amplified, sequenced and subjected to phylogenetic analysis. The phylogenetic tree shows that the viruses belong to clade 2.2 and were most likely introduced to India from China via Europe because isolates share a direct ancestral relationship with the virus isolates of china. The presence of polybasic amino acids at HA cleavage site and also amino acid lysine at 627 position of PB2 protein suggested their capability to cross the host barrier. This change had indicated the propensity of viruses to infect non-avian species and its threats to humanbeing.