福州市2006～2007年乙型流感病毒HA1基因特性的研究

Study on characterization of HA1 gene of influenza B virus between 2006 and 2007 in Fuzhou

目的：了解福州市2006～2007年流行的乙型流感病毒血凝素基因变异特点及种系进化分布。方法：采用狗肾传代细胞培养分离流感病毒，用血凝和血凝抑制试验进行流感病毒型和亚型鉴定，选取部分乙型流感病毒株提取病毒核酸，采用逆转录-聚合酶链反应扩增乙型流感病毒血凝素基因，扩增产物经纯化后，进行血凝素基因HA1区核苷酸序列测定并推导出其氨基酸序列，然后用DNASTAR MegAlign序列分析软件进行基因种系进化特性分析。结果：2006～2007年福州市人群中同时流行着乙型Yamagata系和Victoria系毒株。2006年Victoria系毒株为主要优势流行株，2007年Yamagata系毒株为乙型优势流行株。2006～2007年分离的Yamagata系毒株与B／Shanghai／36I／02比较，在血凝素基因HAl区发生6—10个氨基酸替换，在196位增加一个糖基化位点。2006～2007年分离的Victoria系毒株与B／Zhejiang／2／01比较，在HA1区发生8—9个氨基酸替换，在197位增加一个糖基化位点。与2006～2007年的北半球国际疫苗株B／Malaysia／2506／04比较，在HA1区发生1—3个氨基酸替换。结论：2006～2007年福州市人群中流行的乙型流感病毒与B／Shanghai／361／02和B／Zhejiang／2／01相比基因特性已经发生了进一步改变，抗原已发生漂移。

Objective ：To analyze the genetic characteristics of hemagglutinin gene of influenza B virus to understand its distribution during 2006 - 2007 in Fuzhou. Methods： Viruses were isolated with MDCK cells. The hemagglutination and hemagglutination inhibition tests were used to assay the type and subtype of the viruses and virion RNA were extracted from the representative strains. HA genes of influenza B viruses were amplified by RT - PCR and PCR products were purified and nucleotide sequences of HA1 gene were analyzed and deduced to determine the amino acid sequences. Finally, the phylogenetic tree was analyzed with MegAlign soft ware. Results： The Yamagata - like and Victoria - like viruses were co - circulated in 2006 - 2007. Victoria - like virus had become dominant strains in 2006. Yamagata - like viruses were the main strains in 2007. Compared with B/Shanghai/ 361/02, the Yamagata -like viruses had 6 -9 positions amino acids substitution, and there was one more glycosylation site at 196th site. Compared with B/Zhejiang/2/01, the Victoria-like viruses had 8 -9 amino acids mutation, and there was one more glycoaylation site at 197th site. Compared with the vaccine strain B/Malaysia/2506/04 recommended by WHO ,the Victoria- like viruses had 1 - 3 amino acids substitution. Conclusion： The genetic characteristics and antigenic drift of influenza B viruses had changed comparing with B/Shanghai/361/02 and B/Zhejiang/2/01 in 2006 -2007.