2023年德阳市柯萨奇病毒A6型基因特征分析

Genetic characteristics of coxsackievirus A6 in Deyang city in 2023

目的 分析2023年四川省德阳市柯萨奇病毒A6型(coxsackievirus A6,CVA6)的基因特征.方法 对收集到的2023年德阳市疑似手足口病病例咽拭子标本进行肠道病毒(enterovirus,EV)核酸检测后,选取部分CVA6核酸阳性标本对其VP1区和3D区进行核苷酸序列测定,构建进化树,分析基因特征和变异.结果 2023年用荧光-PCR法共检测355份手足口病咽拭子标本,CVA16核酸阳性47份,非EV-A71/非CVA16的其他EV阳性261份,EV通用型核酸阴性47份.261份其他EV核酸阳性标本中,CVA4、CVA6和CVA10核酸阳性分别检出14份、236份和8份,3份标本未定型.选取20份CVA6核酸阳性标本进行测序,17份VP1区和3D区测序成功.VP1区进化分析显示,德阳市CVA6都均为D3基因亚型.3D区进化分析显示,10份标本属于A重组型(recombinant form A,RF-A),7份标本属K2重组型(RF-K2).不同重组型CVA6 VP1区推导氨基酸差异主要位于73和137位点,3D区推导氨基酸差异主要位于67、75、89、93、97、190、260和263位点.结论 CVA6是2023年德阳市HFMD的优势病原体,RF-A和RF-K2共同流行.需继续加强监测,以了解RF-K2是否持续传播.

Objective To analyze genetic characterization of coxsackievirus A6(CVA6)in 2023,Deyang city,Sichuan province.Methods Throat swab samples collected from probable hand,foot,and mouth disease(HFMD)cases in Deyang in 2023 were detected for enterovirus(EV)by real-time PCR.Some CVA6-positive samples were selected for nucleotide sequencing in both VP1 and 3D region.Phylogenetic trees were constructed and the genetic characteristics and nucleotide/amino acid variation were analyze.Results In 2023,355 throat swab samples of HFMD cases were tested by flueroscence PCR.Forty-seven samples were positive for nucleic acid of CVA16,261 were positive of EVs other than EV-A71/CVA16 and 47 were EV-negative.For the 261 other-EV positive samples,14,236 and 8 samples were nucleic acid positive for CVA4,CVA6 and CVA10,respectively,while 3 samples remained unidentified.Twenty CVA6-positive samples were selected for nucleotide sequencing.Both VP1 and partial 3D region were sequenced successfully in 17 samples.Phylogenetic analysis based on VP1 showed that all 17 CVA6 from Deyang city belonged to D3 subgenotype.The analysis based on 3D indicated that 10 sample belonged to recombinant form A(RF-A),while other 7 belonged to RF-K2.The differences in deduced amino acids between RFs,were at positions 73 and 137 in VP1 region and positions 67,75,89,93,97,190,260 and 263 in 3D region,respectively.Conclusions CVA6 was the predominant causative agent of HFMD in 2023,Deyang city while RF-A and RF-K2 were co-circulating.Surveillance should be enhanced to determine the existence of continuous RF-K2 transmission.