摘要目的:调查2022年绵阳市手足口病病例的感染情况，分析柯萨奇病毒A6型(CVA6)的进化特征。方法:采集2022年绵阳市手足口病患者咽拭子，采用实时荧光定量PCR检测样本中的肠道病毒。对肠道病毒阳性样本使用肠道病毒分型引物进行巢式PCR扩增部分VP1基因，进一步鉴定病毒型别。通过PCR对所有CVA6阳性样本的VP1编码区和部分样本的全基因组进行扩增及测序。对绵阳市流行株进行系统进化、基因同源性、氨基酸变异和基因重组分析。结果:共采集2022年绵阳市手足口病患者咽拭子151份，实时荧光定量PCR检测肠道病毒阳性样本104份，总检出率为68.87%(104/151)。分型结果显示CVA6有77例，阳性率为50.99%(77/151)。本研究扩增测序并成功拼接了77株CVA6 VP1基因全长，系统发育分析表明77株均为D3基因型，与参考株相比，绵阳市流行株存在多处氨基酸变异位点。扩增测序并成功拼接了20条全基因组序列，经同源性分析，20条阳性序列之间核苷酸同源性为97.0%～99.9%。进行系统进化和基因重组分析显示，本次研究流行株在各编码区均未发生基因重组现象。结论:2022年绵阳市手足口病病例中主要病原体为CVA6 D3亚型，与2022年全国流行情况一致。

abstractsObjective:To investigate the etiology of hand, foot and mouth disease (HFMD) in Mianyang city in 2022, and to analyze the genetic characteristics of coxsackievirus A6.Methods:Pharyngeal swabs were collected from patients with HFMD in Mianyang city in 2022. Real-time fluorescence quantitative PCR was used to detect enteroviruses in the samples. Part of the VP1 gene in enterovirus-positive samples was amplified by nested PCR using enterovirus typing primers to further identify the viral types. The VP1 coding region of all CVA6-positive samples and the whole genome of some samples were amplified and sequenced by PCR. The endemic strain in Mianyang city was analyzed for phylogeny, gene homology, amino acid variation and genetic recombination.Results:A total of 151 pharyngeal swabs were collected, and 104 enterovirus-positive samples were detected by real-time fluorescence quantitative PCR, with an overall detection rate of 68.88% (104/151). The typing results showed that there were 77 cases of CVA6 infection, with a positive rate of 50.99% (77/151). The full-length VP1 genes of 77 CVA6 strains were amplified, sequenced, and successfully spliced, and phylogenetic analysis showed that all 77 strains were of the D3 genotype. There were multiple amino acid variant sites in the prevalent strains in Mianyang city compared with the reference strain. Twenty whole genome sequences were amplified, sequenced, and successfully spliced, and homology analysis showed that the nucleotide homology between the 20 positive sequences ranged from 97.0% to 99.9%. Phylogenetic tree and recombination analysis showed that no recombination occurred in the coding regions of the epidemic strains in this study.Conclusions:The predominant pathogen causing HFMD in Mianyang city in 2022 is CVA6 D3 subtype, which is consistent with the national epidemic in 2022.