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目的了解2004年流感流行季节(2004年8月—2005年4月)北京地区婴幼儿急性呼吸道感染患儿中分离到的甲3型流感病毒是否存在抗原性的改变以及其变异程度。方法提取1株于2004年3月和32株于2004年流感流行季节从北京地区急性呼吸道感染患儿中分离到的甲3型流感病毒的病毒RNA,经RT-PCR扩增得到HA1区基因片段并进行核苷酸序列测定,使用生物信息软件分析HA1区基因序列。结果所测定的血凝素HA1区基因均为987bp,编码一个含329个氨基酸的蛋白质。将33株甲3型流感病毒流行株的血凝素(HA1)氨基酸序列与近年WHO推荐的参考疫苗株比较,我们发现一致的多处位点的氨基酸突变,而且突变位点涉及2个抗原决定簇(A、B)和受体结合部位。而2004年3月分离到的毒株在进化分析和氨基酸变异上均不同于2004年流行季节的毒株。结论对血凝素基因HA1区的序列分析结果提示2004—2005年流行季节的甲3型流感病毒较春季的流行株和2004年疫苗株出现了较大的漂移,提示其抗原性可能出现了改变。这种变异对于病毒抗原性的影响以及对于疫苗效果评价的意义值得密切关注。
Objective To understand whether there is antigenic change and degree of variation of influenza A virus isolated from children with acute respiratory infection in infants and young children in Beijing during the influenza season of 2004 (August 2004-April 2005). Methods A strain of influenza virus type 3 virus isolated from children with acute respiratory tract infection in Beijing in March 2004 and 32 strains of influenza in 2004 was collected and amplified by RT-PCR. The HA1 gene fragment The nucleotide sequence of HA1 gene was analyzed by Bioinformatics software. Results The hemagglutinin HA1 gene was 987bp and encoded a 329 amino acid protein. Comparing the amino acid sequence of hemagglutinin (HA1) of 33 influenza A (3) strains with the reference vaccine strains recommended by WHO in recent years, we found consistent amino acid mutations at multiple sites and the mutation sites involved two antigenic determinants Cluster (A, B) and receptor binding sites. However, the strains isolated in March 2004 were different from the strains in the epidemic season of 2004 in evolutionary analysis and amino acid variation. Conclusion The results of sequence analysis of the hemagglutinin gene HA1 region suggest that the influenza A (H3N3) influenza virus in the epidemic season from 2004 to 2005 showed a larger drift than the epidemic strains in spring and 2004, suggesting that the antigenicity might change . The impact of this variation on the antigenicity of the virus and the implications for vaccine effectiveness warrants close attention.