2002年广东省H3N2亚型流感病毒流行的分子基础

目的 了解广东省2002年H3N2亚型流感病毒流行及抗原性变异情况。方法 用狗肾传代细胞(MDCK)和鸡胚进行流感病毒分离，用交叉血凝抑制实验对毒株进行抗原性分析；提取病毒RNA，用一步法RT-PCR扩增血凝素基因(H3A)，产物纯化后，并将其克隆到pMD18—T Vector，进行序列测定和分析。结果 2002年1-10月共获得流感病毒246株，其中H3N2亚型210株，占85．4％，H1N1亚型2株，占0．8％，B型34株，占13．8％；2002年流感流行的高峰是6月；抗原性分析显示，2002年广东省H3N2亚型流感病毒A／粤/236/2002和2001年流行株A／粤／448／2001以及目前国内代表株A／闽／151／2001的抗原比分别是5．6和4．0；其HAl区氨基酸序列和国际代表株A／悉尼／5／97同源性为94．2％，有19个氨基酸差异，其中发生在抗原决定族A、B、E上的有6个，受体结合部有3个。结论 2002年广东省流感病毒以H3N2亚型为主，其流行的分子基础是基因变异导致抗原性发生漂移。

The Molecular Basis of the Prevailing of Influenza A(H3N2) Prevail in Guangdong Province in 2002

Objective To understand the epidemics and antigenic drift of influenza A(H3N2) viruses in Guangdong province in 2002. Method Influenzas viruses isolated were cultured in MDCK cell and embryonated eggs. The cross hemagglutination inhibition test was used for antigenic analysis. Virion RNAs were extracted and amplified by one-step RT-PCR. The PCR were purified and cloned into pMD18-T vector for sequencing. Phylogenetic analysis of the sequencing data was performed with the Megalign and Editseq software.Results 246 influenza strains were obtained,including 210(85.4%)strains of H3N2,2(0.8%) strains of H1N1, 34(13.8%) strains of B. The prevailing of influenza A(H3N2) was peaked at June. The antigenic ratio was 5.6 between A/Guangdong/236/2002 and A/Guangdong/448/2001, and 4.0 between A/Guangdong/236/ 2002 and domestic reference stain A/Fujian/151/2001.The amino acid sequence on HAl domain of the A/Guangdong/236/2002 strain showed a 94.2% homology with the international representative strain A/Sendey/5/97(H3N2) .There were six amino acid changed in A, B, E antigenic determination, and three amino acid changed in receptor bind site. Conclusion Influenza A (H3N2) viruses predominated in 2002,and the molecular basis of epidemic were gene variation leading to antigenic drifts of this influenza A(H3N2).