广西2株H9N2亚型猪源流感病毒的HA基因序列分析

HA Gene Sequence Analysis of Two H9N2 Subtype Swine Influenza Virus in Guangxi

【目的】了解广西H9N2亚型猪源流感病毒的分子流行病学特征并揭示其遗传变化规律,为有效防控猪流感提供参考依据。【方法】运用PCR方法扩增广西2株H9N2亚型猪源流感病毒(A/swine/Guangxi/P2/2011和A/swine/Guangxi/P3/2011)的HA基因,并进行克隆测序及序列比对分析,绘制遗传进化树。【结果】2株H9N2亚型猪流感分离株的HA基因全长1701 bp,开放阅读框(ORF)全长1683 bp,编码560个氨基酸;与参考毒株核苷酸的同源性在83.7%~98.3%,推导氨基酸同源性在86.6%~98.2%。遗传进化树分析结果显示,2株分离株与A/Duck/HongKong/Y280/97病毒同属欧亚谱系的Y280亚系,其HA基因的裂解位点序列均为RSSR↓GLF,具有低致病性流感病毒的分子生物学特征;共有8个糖基化位点,其中6个位于HAl区,2个位于HA2区;HA受体结合位点均具有人流感病毒和猪流感病毒特征。【结论】分离获得的广西2株H9N2亚型猪源流感病毒A/Swine/Guangxi/P2/2011和A/Swine/Guangxi/P3/2011,其HA基因属于欧亚普系的Y280亚系,均具备典型的低致病性和与人流感受体结合特征。

【Objective】To provide a better control and prevention of swine influenza H9N2,we analyzed the HA gene to understand the molecular epidemiology and revealed its genetic variation.【Method】By using RT-PCR technique,the HA gene of two strains of H9N2 swine influ-enza virus(A/swine/Guangxi/P2/2011 and A/swine/Guangxi/P3/2011)were amplified,cloned and sequenced while analyzed by phylogenetic tree.【Result】The HA gene of both strains was 1701 bp and their ORF was 1683 bp in length respectively which encoded 560 amino acids.The nucleotide homology with reference strain was 83.7%to 98.3%and the deduced amino acid homology was 86.6%-98.2%respectively.The phylogenetic tree analysis revealed that the two isolates were most closely related to A/Canine/Guangxi/1/2011 and belonged to A/duck/Hong Kong/y280/97 virus.The cleavage sites sequences of HA gene of both isolates were RSSR↓GLF,which were low pathogenic influenza virus.There were 8 glycosylation sites,6 in HAI region and 2 in HA2 region.The amino acids at RBS sites of HA protein of Guangxi isolates had been characterized by both human and swine influenza virus.【Conclusion】Both of strains,A/Swine/Guangxi/P2/2011 and A/Swine/Guangxi/P3/2011(H9N2)HA genes belong to Y280 subfamily of the Eurasian genus and have typical low pathogenicity,sexual and human influenza binding characteristics.