Analysis the variation of HA of influenza H1N1 virus in Guangzhou in 2010

Objective To compare the variation of HA of influenza A(H1N1) from Guangzhou in 2010 with the influenza A(H1N1) virus from Chinese Mainland in 2009.The results will provide basis for the surveillance of influenza A(H1N1)virus.Methods Specimens were collected from patients with febrile respiratory tract symptoms in Guangzhou in 2010.The specimens were tested for influenza A(H1N1)by PCR using specificity primers.PCR products of HA were sequenced.Then compared with the sequence of influenza A(H1N1)in 2009.The antigenic sites and glycosylation sites of HA were analyzed using biometric software.Results In total,426 specimens were tested.211 influenza A viruses strains were detected and 4 of the strains were identified as the influenza A(H1N1) subtype.Compared with influenza A(H1N1) virus in 2009,there are 12 amino acids changed.6 of those changes were located in antigen determinant sites.AA145 was changed in all 4 influenza A(H1N1).There are two strains having mutation in AA180.There was variation between the phylogenetic trees based on the representative strains in 2009 and the strains in 2010.Conclusion Compared with representative strains in 2009,two amino acid(145S and 180E) were changed on receptor binding sites,which may be important for variation of the antigens.Antigen may have a genetic drift in the A/Guangdong/ZS03/2010(H1N1) and A/Guangdong/ZS01/2010(H1N1).