2018-2021年云南省手足口病病例柯萨奇病毒A4型流行株基因特征

Genetic characteristics of coxsackievirus A4 isolated from hand, foot, and mouth disease cases in Yunnan province from 2018 to 2021

目的 分析云南省手足口病(Hand, foot and mouth disease, HFMD)病例柯萨奇病毒A组4型(Coxsackievirus A4,CVA4)分离株基因特征。方法 在云南省7个市州采集2018-2021年HFMD病例粪便标本,进行肠道病毒RNA提取、VP1区基因扩增、序列测定和基因型别鉴定;构建CVA4分离株与基因库中参考株系统进化树,分析核苷酸和氨基酸相似性。结果 从28 565例HFMD病例粪便标本中获得13株CVA4,其中2018年1株、2019年1株、2020年6株、2021年5株;C2基因亚型11株、C4基因亚型2株。C4和C2基因亚型之间核苷酸、氨基酸平均相似性分别为85.77%、93.27%;与原型株HighPoint相比,C2基因亚型核苷酸、氨基酸平均相似性分别为84.51%、93.27%,C4基因亚型分别为84.44%、93.78%。结论 2018-2021年云南省HFMD病例CVA4的优势流行株为C2基因亚型;需继续加强CVA4分子流行病学监测。

Objective To analyze genetic characteristics of coxsackievirus A4(CVA4) isolated from hand, foot, and mouth disease(HFMD) cases in Yunnan province.Methods We collected stool samples from HFMD cases in 7 prefectures of Yunnan from 2018 to 2021 to obtain enterovirus RNA for amplifying VP1 region genes, sequencing, and identifying genotypes. We constructed a phylogenetic tree between the CVA4 isolates and reference sequences from GenBank and determined nucleotide and amino acid similarities.Results A total of 13 CVA4 strains were detected in stool samples of 28 565 HFMD cases with 1, 1, 6, and 5 strains in 2018, 2019, 2020, and 2021, respectively;11 and 2 strains were identified as C2 and C4 sub-genotypes. Average similarities of nucleotides and amino acids between C4 and C2 sub-genotypes were 85.77% and 93.27%. Compared with the prototype strain, HighPoint, average similarities of nucleotide and amino acid for C2 sub-genotype were 84.51% and 93.27%%, and for C4 sub-genotype were 84.44% and 93.78%.Conclusions The predominant genotype of CVA4 circulating in Yunnan from 2018 to 2021 was C2 sub-genotype. We should strengthen molecular epidemiological surveillance for CVA4.