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目的了解2009年5月~2010年4月间北京地区乙型流感的流行特征及血凝素(HA1)变异情况。方法采用real-time RT-PCR法对流感样疑似病人咽拭子进行乙型流感病毒检测,采用DNA Star软件对HA1基因片段核苷酸和氨基酸序列进行系统进化分析。结果 2009年5月~2010年4月共收集并检测流感样疑似病例咽拭子样本2 138份,乙型流感病毒阳性169例,总阳性率为7.9%,且以2010年2月阳性率最高。乙型流感病毒阳性者平均年龄为(35±24)岁,显著高于对照组中的(28±19)岁(P<0.001);女性组中乙型流感病毒阳性率为11.8%,显著高于男性组的7.9%(P<0.015)。HA1片段序列分析显示本地区的乙型流感病毒属于Victoria系,与参考株B/Brisbane/60/2008相比,其核苷酸、氨基酸的同源性分别为93.4%~99.2%和99.3%~99.7%;2个氨基酸发生改变。结论 2009年5月~2010年4月期间北京地区乙型流感病毒的流行高峰为2010年1、2月,主要累及的人群为35岁以上的女性。本地区的优势流行株仍属于Victoria系,其抗原性未发生明显改变,提示以往流感疫苗仍有较好的保护效果。
Objective To understand the prevalence of influenza B and the variation of hemagglutinin (HA1) in Beijing from May 2009 to April 2010. Methods The real-time RT-PCR method was used to detect influenza B virus in throat swabs of influenza-like patients. Phylogenetic analysis of the nucleotide and amino acid sequences of HA1 gene fragments was performed using DNA Star software. Results From May 2009 to April 2010, a total of 2 138 throat swab samples from suspected flu-like cases were collected and tested. The positive rate of influenza B virus was 169 and the total positive rate was 7.9%. The positive rate was highest in February 2010 . The average age of Influenza B (35 ± 24) years was significantly higher than that of the control group (28 ± 19 years) (P <0.001). The positive rate of influenza B in women was 11.8% 7.9% of the male group (P <0.015). The sequence analysis of HA1 showed that the influenza B viruses belonged to the Victoria family in the region, and the nucleotide and amino acid homologies were 93.4% -99.2% and 99.3% -96%, respectively, compared with the reference strain B / Brisbane / 60 / 99.7%; 2 amino acids changed. Conclusions The prevalence of influenza B virus in Beijing from May 2009 to April 2010 was January and February 2010, and the main population affected was female over 35 years old. The dominant epidemic strains in this area still belonged to the Victoria family. The antigenicity did not change significantly, suggesting that the flu vaccine still had a good protective effect in the past.