一起聚集性发热伴血小板减少综合征病原S基因分子进化分析

目的 对2020年4月南京鼓楼医院送检的一起疑似聚集性发热伴血小板减少综合征(SFTS)开展病原检测,对其S基因进行测序,分析基因分型和系统发育特征。方法 采用荧光定量PCR法对6例疑似患者血清标本进行新型布尼亚病毒(SFTSV)核酸定性检测, RT-PCR扩增SFTSV S基因片段并测序。分析核苷酸同源性,构建系统进化树。结果 6例血清样本中,SFTSV核酸阳性5例。5例核苷酸高度同源,其中4例S片段基因核苷酸序列同源性100%,1例与其他4例间同源性为99.7%;最大相似株为江苏2014年分离株JS2014-06、2015年分离株JS2015-26,同源性100%。5例均聚集在C2亚型分支上。结论 聚集性疫情SFTSV基因型为C2型,与近年来国内分离株亲缘关系近。需加强监测和宣教,关注病毒的进化与变异。

Phylogenetic analyses of the S gene of SFTSV in a cluster of cases of severe fever with thrombocytopenia syndrome

To detect the pathogen involved in a cluster of cases of severe fever with thrombocytopenia syndrome (SFTS) from Nanjing Gulou Hospital in April 2020, the S gene of the pathogen was sequenced, and the genotype and phylogenetic characteristics were studied. Nucleic acid qualitative detection of SFTSV was carried out by the fluorescence quantitative PCR method in six cases with serum samples taken in the acute stage. The S fragments of positive samples were amplified by RT-PCR and sequenced. Nucleotide homology was analyzed and a phylogenetic tree was constructed. Five of the six serum samples were positive for SFTSV, and the five cases were highly homologous: four had 100% homology of the S fragment nucleotide sequence, and one case had 99.7% homology with the other four cases. The most similar strains were isolated from Jiangsu in 2014 (JS2014-06) and 2015(JS2015-26), with 100% homology. The five cases were all in a branch of the C2 subtype. The SFTSV genotype of this cluster outbreak is C2 and its nucleotides are highly homologous with domestic isolates in recent years. Monitoring and education need to be strengthened and we should pay attention to the evolution and mutation of the virus.