泉州市流感疫情实验室检测及H3N2亚型基因特性分析

Laboratory diagnosis and genetic characterization analysis of the subtype A3 influenza viruses in Quanzhou

目的 了解2009年泉州地区流感流行及病毒株的变异情况,探讨流感病毒基因的变异与流感流行的关系.方法 对泉州市198例流感患者的咽拭子采用MDCK细胞培养进行病毒分离,经血清学试验鉴定分型和实时荧光RT-PCR方法检测病毒核酸.对其中4株毒株提取病毒RNA,采用RT-PCR扩增病毒HA1基因,纯化产物进行核苷酸序列测定,用DNAstar megalign软件分析基因.结果 198份咽拭子中有98份为H3N2亚型流感病毒核酸阳性,分离到62株H3N2亚型流感病毒,HA1基因经核苷酸序列测定显示,其基因特性更接近于A/Ningbo/333/2008,核苷酸同源性为98.7%,与A/Xiamen/70/2004的同源性为96.8%,由HA1基因核苷酸序列推导的氨基酸系列与疫苗株A/Brisbane/10/2007相比,有7个氨基酸位点发生变异,其中有1个位点位于抗原决定簇A区（144）,有2个位点位于抗原决定簇B区（158、189）,种系发生树分析也证实HA1基因存在一定差异.结论引起2009年泉州市流感在部分集体单位流行的病毒为H3N2亚型,其基因特性和抗原性与疫苗株相比均发生了一定变异.

Objective To obtain the information of the 2009 influenza outbreak and the variations of influenza virus strains in quanzhou, and explore the relationship between the genetic variation of influenza virus and influenza epidemic. Methods During the influenza outbreak in quanzhou,one hundred and ninetyeight throat swabs specimens from the patients with influenza were collected. Viruses were isolated with MDCK cells and identified with serological test, followed by real-time RT-PCR. RNA of four influenza virus strains were extracted, then HA1 gene was amplified by RT-PCR. The purified PCR products were sequenced. The data were analyzed with the software DNAstar megalign. Results Total 98 pieces of H3N2 subtype influenza virus nucleic acid were detected in 198 throat swabs specimens,among which 62 influenza virus strains were identified as subtype influenza A（ H3N2 ）. The sequencing results of HA1 gene in these positive strains showed that their genetic characterization were more closed to strains A/Ningbo/333/2008 with a nucleotide homology of 98.7%, which was 96.8% as compared with A/Xiamen/70/2004. The amino acids sequences deduced from the nucleotide sequences in HA1 region of the isolated strain had 7 mutant sites compared with A/Brisbane/10/2007 vaccine strain. One variant amino acids were found located in the antigenic determinant sites A（ 144 ）, two were in the sites B（ 158,189 ）. Phylogenetic analysis also confirmed the difference in HAl domain. Conclusion The influenza virus strains causing the flu outbreak among some communities of quanzhou in 2009 are subtype influenza A （ H3N2 ）, whose genetic characterization and antigenicity were different from the vaccine strain.