一起学校聚集性感染B型流感病毒的病原学特征分析

Analysis of the etiological characteristics of an outbreak of influenza B virus infection

目的对引起淮安市一起聚集性流感疫情的B型流感病毒病原学特征进行分析,为B型流感的防控提供参考。方法收集15例患者的咽拭子标本,利用实时荧光RT-PCR方法进行流感病毒的快速检测,对流感病毒核酸阳性的标本进行HA1基因扩增、测序,利用Lasergene软件进行序列比对及核苷酸同源性分析,并分析血凝素主要的抗原决定簇位点;利用Mega6.0软件构建系统进化树。结果引起聚集性感染的病原体为B型流感病毒,进化树分析显示该病毒为Yamagata系流感病毒,淮安株间的核苷酸同源性为98.2%~99.8%,与江苏株B/Jiangsu-Tianning/11011/2014和浙江株B/Zhejiang-Liandou/11000/2014等的同源性为96.1%~99.7%。与疫苗株相比,淮安株10个氨基酸位点的替换有普遍性,其中有4个位点位于抗原决定簇。结论引起淮安市学校聚集性B型流感的病原体均为Yamagata系B型流感病毒,应加强学校疫情监测并督促防控措施落实。

Objective The pathogenic characteristics of influenza B virus causing a cluster of flu outbreaks in Huai＇an were analyzed to serve as a reference for the prevention and control of influenza B virus. Methods Throat swab specimens were collected from 15 patients.A real-time fluorescence polymerase chain reaction was used to detect the influenza virus.The HA1 gene was amplified and sequenced.Sequence alignment and nucleotide homology analysis were performed using the software Lasergene,and the main antigenic sites of hemagglutinin were analyzed.A phylogenetic tree was constructed using the software Mega6.0. Results The pathogen causing the cluster of infections was the influenza B virus.Phylogenetic analysis indicated that the virus was a Yamagata flu virus.Nucleotide sequences of influenza B virus isolates were 98.2-99.8% similar to those of the Huai＇an strains and 96.1-99.7%similar to those of the Jiangsu strain B/Jiangsu-Tianning/11011/2014 and the Zhejiang strain B/Zhejiang-Liandou/11000/2014.Ten amino acids were widely substituted in comparison to vaccine strain B/Massachusetts/2/2012.Four of the amino acids were antigenic determinants.Conclusion The pathogen that caused a cluster of infections in schools in Huai＇an was the Yamagata lineage of the influenza B virus.Surveillance of the prevalence of the influenza B virus in schools should be enhanced,and prevention and control measures should be implemented.