Variation of HA gene of influenza A H1N1 influenza virus isolated from 2009 to 2014 in Chongqing city / 重庆医学

ABSTRACT

Objective In order to analyze the variation of HA genes of influenza viruses (H1N1) by being compared with the vaccine strain A/California/07/2009(H1N1) recommended by WHO ,influenza viruses (H1N1) isolated from 2009 to 2014 were selected to do this study .Methods According to the different isolating time and place ,47 strains of H1N1 collected from 2011 to 2014 were selected .Then the 47 strains′ nucleotide sequence of HA genes which were sequenced in the study and other 25 se‐quences of HA genes which were sequenced in 2009 were collected .Nucleotide and amino acid sequences were analyzed by using molecular biology software ,and the phylogenetic trees were drawn .Results A total of 72 strains isolated from 2009 to 2014 were closely related to the vaccine strain A/California/07/2009(H1N1) ,the nucleotide variance and amino acid variance between the 72 strains were 0-2 .7% and 0-3 .1% respectively .Compared with the vaccine strain A/California/07/2009(H1N1) ,the nucleotide variance and amino acid sequence variance were 0 .4% -2 .4% and 0 .9% -3 .1% respectively .The amino acids sequence indicated that ,although the variance was increased by years ,the H1N1 viruses were still showed characteristics of low pathogenic influenza viruses .It was also found that there were 9 strains lost their potential glycosylation site at HA protein site 481 in 2009 ,while in 2013 there were 6 strains got new potential glycosylation sites at HA protein site 162 .Conclusion The vaccines (H1N1) recom‐mended by WHO was still protective to people in Chongqing .But as time goes by ,antigen drift may occur in some new antigenic drift strains and the routine monitoring of influenza viruses should be continued .