上海和无锡流感病毒病原学监测及血凝素基因变异

Surveillance of hemagglutinin genetic variation of influenza viruses in Shanghai and Wuxi

目的了解2004至2006年流感流行季节流感病毒型及亚型在上海及无锡两地流感样患者中流行情况及病毒型内血凝素(HA)基因变异状况。方法与上海及无锡市疾病预防控制中心合作,对门诊流感样患者及集体单位聚集性流感样暴发患者采集鼻咽拭标本,接种MDCK细胞,分离流感病毒,直接荧光免疫法鉴定阳性分离株型别,对甲型流感病毒采用RT-PCR鉴定亚型,并对部分H3、H1亚型流感病毒进行HA全基因片段测序,分析流感病毒HA基因变异状况。结果2004年8月至2006年9月,上海及无锡两地流感样患者中共分离到126株流感病毒,其中53株为H3N2亚型,43株为H1N1亚型,30株为B型。聚集性流感样疾病暴发多在2、3月份,分析7起聚集性流感样疾病暴发,分别为H3N2流感病毒感染2起,H1N1流感病毒感染1起,B型2起,及H3N2、B和H1N1、B混合感染各1起。HA序列分析,H1、H3与同期其他国家和地区的分离株近源。结论上海及无锡两地散发和局部暴发的甲型流感病毒感染仍主要为H1N1、H3N2亚型,未发现HA、NA重组株和新的HA、NA亚型;1～3月份为发病高峰;H1、H3型内变异状况与其他国家和地区相似。

Objectives To explore the type and subtype distribution of influenza viruses in influenza-like patients and the hemagglutinin （HA） genetic variation of influenza A viruses in Shanghai and Wuxi during the influenza prevalent season from 2004 to 2006. Methods Throat swabs were collected from the influenza-like patients in the sentinel hospitals and during the outbreaks, and then inoculated into MDCK cells to isolate influenza viruses, which were subsequently identified by direct immunofluorescence（DIF） and reverse transcription-polymerase chain reaction （RT-PCR）. HA segments of influenza A viruses were sequenced to analyze the genetic variation of HA. Results One hundred and twenty-six strains of influenza viruses, including 53 H3N2, 43 H1N1 and 30 influenza B viruses were isolated from August 2004 to September 2006, and 7 outbreaks. All these outbreaks occurred in February or March The pathogens were identified as H1N1 in one outbreak, H3N2 in two outbreaks, B in two outbreaks and mix infections in two outbreaks （1 H1N1 and B, 1 H3N2 and B, respectively）. By sequencing the HA segment, the H3 and H1 segments were all homologous to the isolates from different countries in the same period. Conclusions H3N2 and H1N1 are the major strains prevalent in Shanghai and Wuxi, which reach the peak from January to March No HA and NA recombinant strains and new HA and NA subtypes are found in these areas. The variations of H1 and H3 are similar to those found in other countries.