2018–2020年人轮状病毒锦州地方株VP4及VP7基因特征

Gene characterization of human rotavirus Jinzhou strains VP4 and VP7 during 2018 and 2020

摘要:

【背景】人A组轮状病毒(Rotavirus Group A，RVA)是婴幼儿胃肠炎的主要病原体及发展中国家婴幼儿死亡的重要原因，目前无特效药物治疗，疫苗预防是唯一可行的预防感染方法。外衣壳蛋白VP7和VP4是疫苗设计的主要靶点，针对该基因加强RVA地方株分子流行病学监测十分必要。【目的】对锦州地方流行RVA株VP7和VP4基因进行型别鉴定和序列特征分析。【方法】收集锦州地区2018?2020年RVA感染腹泻患儿的粪便标本，提取病毒RNA，通过RT-PCR扩增VP7、VP4基因片段并测序，得到7株RVA VP7和VP4序列。使用在线基因分型工具RotaC v2.0对测序结果进行分型分析。应用BLAST、DNAstar、Mega X、Bioedit等生物软件与临床流行株及疫苗株进行系统发育分析及氨基酸序列比对分析。【结果】分型结果表明7株锦州地方株均为G9P[8]型，系统发育分析证实其VP7和VP4基因分别属于G9-Ⅵ和P[8]-3谱系，核苷酸序列相似性分别为99.32%?100%与99.41%?100%。JZ株VP7与疫苗株Rotavac和Rotasiil相比，在抗原表位区7-1a、7-1b、7-2中分别存在4个和3个氨基酸替换。JZ株VP4与疫苗株Rotarix和RotaTeq VP4氨基酸序列相比，发现7个和4个氨基酸替换，位于抗原表位区8-1和8-3。【结论】2018?2020年在辽宁锦州地区检测到7株G9P[8]型RVA株，VP7和VP4序列相似性高于99%，G9P[8]型可能是辽宁省锦州地区2018?2020年婴幼儿轮状病毒腹泻的主要流行基因型之一。与同基因型疫苗株比较，位于JZ株VP7和VP4抗原表位区的氨基酸位点差异对于野毒株免疫逃逸机制的研究具有意义。

Abstract:

[Background] Human rotavirus group A (RVA) is the main pathogen of gastroenteritis in infants and important cause of infant death in developing countries. There are no specific drugs until now and vaccines are the only feasible method to prevent infection. As outer capsid proteins VP7 and VP4 are the main targets of rotavirus vaccine, it is necessary to strengthen molecular epidemiological surveillance of local clinical circulating RVA strains against these genes. [Objective] To identify VP7 and VP4 genotypes and analyze their sequence characterization of RVA circulating strains in Jinzhou. [Methods] The fecal samples of infants suffered from RVA infection diarrhea in Jinzhou during 2018?2020 were collected and viral RNA were extracted. VP7 and VP4 gene fragments were amplified by RT-PCR and PCR products were sequenced. Seven RVA strains VP7 and VP4 genes were obtained. The sequencing results were analyzed by genotyping using online tool RotaC V2.0. Phylogenetic and amino acid sequence alignments analysis compared to clinical epidemic strains and vaccine strains were carried out with BLAST, DNAstar, Mega X, Bioedit. [Results] The genotyping results showed that 7 Jinzhou strains in this study was G9P[8]. Phylogenetic analysis confirmed that VP7 and VP4 belonged to lineages G9-Ⅵ and P[8]-3, and nucleotide sequence identity were 99.32%?100% and 99.41%?100%, respectively. There were 4 and 3 amino acid substitutions in the antigen epitope regions 7-1a, 7-1b, 7-2 when JZ strains VP7 were compared with vaccine strains Rotavac and Rotasiil VP7. The amino acid sequences of JZ strains VP4 were compared with vaccine strains Rotarix and RotaTeq VP4. Seven and four amino acid substitution sites located in the antigen epitope regions 8-1, 8-3 were found. [Conclusion] Seven G9P[8] RVA strains were detected in Jinzhou, Liaoning province from 2018 to 2020. The identity of VP7 and VP4 sequences was higher than 99%. G9P[8] was probably one of the main epidemic genotypes of infantile rotavirus diarrhea in Jinzhou, Liaoning province in 2018?2020. Compared to the same genotypic vaccines strains, amino acids variations located in VP7 and VP4 epitope regions of JZ strains are significant for understanding immune escape mechanisms of wild RVA strains.