甲型流感病毒血凝素基因变异与抗原变异关系研究

目的 了解甲型流感病毒流行株的血凝素基因变异和抗原变异及两者间的关系,结合流行病学资料分析基因变异和抗原变异的吻合情况.方法 从2005-2007年上海市季节性流感样病例分离到的甲型流感病毒株中,选取H1N1、H3N2两个亚型中部分有代表性的病毒株,并同WHO北半球流感疫苗推荐株一起,进行血凝素全基因序列测定后做基因进化树分析.同时用灭活的全病毒抗原免疫金黄地鼠,通过血凝抑制试验测定病毒的血凝效价,对血凝抑制结果进行聚类分析,绘制病毒的抗原变异图.结果 H3N2分离株与WHO北半球疫苗推荐株A/Sydney/5/97、A/Fujian/411/2002处于不同的基因进化分枝上,时间间隔越久,进化距离越远,同样的结果也出现在抗原变异分析中.而H1N1分离株的基因变异情况和抗原变异情况则不一致,在基因变异中,与疫苗推荐株A/New Caledonia/20/1999的距离远近受到分离时间的影响,抗原变异还与病毒是否从散发病例或聚集性病例分离有关.结论 流感病毒血凝素的基因变异和抗原变异的结果基本吻合,采用流行株免疫血清的血凝抑制试验能更好地反映病毒的变异和进化情况.

Study for the correlation between genetic diversity and antigenic variation of hemagglutinin in influenza A viruses

Objective To study the correlation between genetic diversity and antigenic variation of hemagglutinin in influenza A viruses and analyze the coincidence of these two variations with epidemiological data. MethodsA/H1N1 and A/H3N2 influenza viruses isolated from flu-like cases in Shanghai and surrounding areas during 2005-2007 influenza seasons as well as some vaccine strains for northern hemisphere recommended by WHO were used. The correlation between genetic diversity and antigenic variation of hemagglutinin in influenza A viruses was studied. Full-length sequence encoding hemagglutinin was determined and analyzed by phylogenetic tree analysis. Golden hamsters were immunized with inactivated influenza viruses, and their sera were titrated for the virus hemagglutinin by hemagg/utination inhibition assay (HIA). HIA data were clustered and mapped. Results A/H3N2 viruses isolated in Shanghai and WHO recommended vaccine strains, such as A/Sydney/5/97-like and A/Fujian/411/2002-like, were located at different clusters. The distance was associated with time when the virus was isolated. The more the interval time between isolations, the longer was the distance. Similar trend was found in antigenic variation. In A/H1N1 strains, however, the antigenic variation was not in accordance with the genetic diversity. The distances of genetic diversity between Shanghai isolates and the WHO recommended vaccine strain, A/New Caledonla/20/1999-like, were influenced by time. Whereas, the distance of antigenic variation was not only associated with the time of isolation but also with the virus strains isolated from sporadic or clustered cases. Conclusions The genetic diversity of hemagglutinin is similar to antigenic variation of hemagglutinin in influenza A viruses, and the mutation and evolution of hemagglutinin antigen can be better reflected with HIA by using the immune sera of epidemic strains.