一起由柯萨奇病毒A4引起的聚集性发热的分子流行病学研究

Molecular epidemiological analysis of a cluster offebrile illness caused by coxsackievirus A4

目的对2018年北京市一起聚集性发热疫情的病原进行鉴定,并对其进行分子流行病学分析。方法采集此次疫情4例患儿咽拭子标本,提取标本核酸,用实时荧光PCR对其进行初步病原学鉴定。用分型引物通过RT-nPCR对肠道病毒VP1区部分核苷酸序列进行扩增,通过测序和GenBank Blast比对确定肠道病毒型别,并对其进行序列和进化分析。结果 4例患儿标本均为CVA4阳性,在VP1区,其核苷酸序列同源性为100%;序列分析发现,其与2016年澳大利亚CVA4分离株MH111027同源性最高,为99%;与2004—2016年中国境内CVA4分离株同源性为83%～90%。进化分析显示,此次疫情毒株与近年来中国境内流行的CVA4优势毒株不在一个进化树分支上。结论引起此次聚集性发热疫情的病原体是CVA4,其与近年来我国流行的CVA4优势毒株具有不同的种系来源。

Objective To identify the causative agent of a cluster of febrile illness in Beijing in 2018, and to analyze its molecular epidemiological characteristics. Methods Throat swabs were collected from 4 cases of the cluster. RNA was extracted and preliminary identified by real-time PCR. Partial VP1 sequences were amplified by RT-nPCR with HEV typing primers. The virus type was identified by sequencing and GenBank Blast. Sequence and phylogenetic analyses were performed. Results Samples of the 4 cases were tested positive for CVA4. During the VP1 region, nucleotide identity between the 4 CVA4 strains were 100%. They shared the highest nucleotide identity of 99% with MH111027 isolated from Australia in 2016, and shared the relatively low nucleotide identities of 83%-90% with the domestic CVA4 strains isolated in 2004-2016. Phylogenetic analysis showed that the CVA4 strains in this study were not clustered with the dominant CVA4 strains epidemic in recent years in China. Conclusion The causative agent of the cluster of febrile illness was CVA4, and its lineage was different from the dominant CVA4 stains epidemic in China in recent years.