中文摘要：

目的 分析广东地区2012-2013年新型H1N1（pH1N1）病毒血凝素（HA）基因、表位和受体结合位点（receptor binding sites,RBS）进化特征和选择性。方法 检测广东地区2012-2013年分离的pH1N1毒株HA基因核苷酸序列,与GenBank中全球相应毒株序列比对,应用MEGA 6.05构建进化树,通过Chimera v1.8.1建模并标记,应用DATAMONKEY筛选HA选择性位点。结果 与疫苗株A/California/07/2009的HA基因比较,广东地区2012-2013年pH1N1毒株的HA基因同源性为98.1%~98.7%;变异位点H155Q、K180Q/N和S202T分别位于HA抗原的Ca2、Sa和Sb表位,S220T和R222K均位于HA抗原的Ca1表位区域;位点A151V位于RBS的140环上。正向选择位点为AA202位点。广东毒株A/Guangdong/64/2013与其他毒株相比,发生6个氨基酸位点变异,包括V6I、N55S、S101G、A151V、H155Q和V267A。结论 广东2012-2013年pH1N1毒株HA基因变异导致了HA抗原表位和RBS 140环位点变异将分别影响毒株的抗原性和受体功能;正向选择位点AA202位点承受着较大的免疫压力;毒株A/Guangdong/64/2013的抗原表位Ca2和RBS位点变异可能是下个流感流行季节优势毒株的分子基础。

英文摘要：

Objective To reveal the molecular characteristics and evolutionary selection of hemagglutinin （HA） genes of pandemic H1N1 （pH1N1） viruses isolated from 2012 to 2013. Methods The HA genes of Guangdong influenza pH1N1 viruses Guangdong from the year of isolated during 2012 to 2013 were sequenced and compared with global HA genes downloaded from GenBank. The phylogenetic tree and the molecular model of HA genes was conducted respectively by MEGA 6.05 and Chimera vl. 8.1 as the selected sites were analyzed by DATAMONKEY. Results Compared with HA genes of vaccine strain A/California/ 07/2009, the HA genetic homologies of Guangdong strains during 2012 to 2013 reached to 98.1% to 98.7%. There were some amino acid substitutions including H155Q （Ca2 epitope）, K180Q/N （Sa epitope）, S202T （Sb epitope）, S220T （Cal epitope） and R222K （Cal epitope）, where the A151V was located in receptor binding sites （RBS） 140 loop. Residue 202 was revealed to be the positively selected site. Moreover, the HA amino acid mutations of A/Guangdong/64/2013 occurred in V6I, N55S, S101G, A151V, H155Q and V267A. Conclusion The mutations in HA genes of Guangdong pH1N1 viruses during 2012 to 2013 lead to variations in antigenic epitopes and RBS loop, which might respectively influence the antigenicity and the receptor-binding. Mutation AA202 with positive selection means to be borne the great immunological pressure on it. Epitope Ca2 and RBS mutation sites in strain A/Guangdong/64/2013 could contribute to the dominantstrain in the following influenza season.