宁波市甲3型流感的流行与基因演变连续7年监测分析

Analysis on the correlation between human influenza A/H3N2 hemagglutinin gene variation and the epidemic from 2002 to 2008 in Ningbo

目的了解甲3型流感病毒的抗原变异与流感流行的关系。方法用狗肾传代细胞（MDCK）分离流感病毒，逆转录．聚合酶链反应（RT-PCR）扩增血凝素基因产物，纯化后进行核苷酸序列测定。结果2002-2008年，宁波市流感流行有春季和夏秋季两个季节性高峰，而病毒抗原性突变大多发生在夏秋季这一季节。2002-2005年在血凝素基因HA1片断的变异较快，且第225～228位之间的氨基酸每年都有突变；而2005-2008年间这一区域却相当稳定。结论同一亚型的流感病毒在春季刚流行后紧接着夏秋季再次引起流行这可能与病毒的变异多数发生在每年的下半年有一定联系。甲3型流感2002-2005年的流行强度较2005～2008年强，可能与前者的血凝素基因HA1片断第225-228位每年都发生改变而后者却相当稳定有关。

Objective To study the correlation between human influenza A/H3N2 hemagglutinin gene variation and the epidemic from 2002 to 2008 in Ningbo. Methods Influenza virus was isolated by means of inoculation in Madin-Darby Canine Kidney （MDCK） cells. Viral RNA was extracted and transcribed into cDNA by reverse transcriptase and amplified by PCR. Finally, the PCR product was purified and nucleotide sequence was determined. Results Two influenza A virus peaks were found in the springtime and summer or autumn per annum. We also noticed that most amino acid changes happened in the summer or autumn. Additionally, the changes in HA1 of hemagglutinin gene in the 225-228 sites were brisk from 2002 to 2005, whereas, there were no changes in these sites from 2005-2008. Conclusion Identical subtype virus of influenza epidemics in the springtime followed by epidemics in the summer or autumn were related with most changes of amino acid in the second half of the year. The influenza A/H3N2 activity in the 2002-2005 more powerful than that in the following years was related with changes in HA1 of hemagglutinin gene in the 225-228 sites perhaps.