南通地区9株4型星状病毒的全基因组序列分析

Whole-genome Sequence Analysis of Nine HAstV-4 Strain in Nantong Area,China

人类星状病毒(Human astrovirus,HAstV)是全球流行的引起急性胃肠炎常见病原体,主要引起幼儿、老年人及免疫功能低下人群的感染。本研究收集了江苏南通地区定点监测医院门、急诊<5岁儿童急性胃肠炎腹泻监测粪便标本712份,共检测出HAstV阳性22例。对Ct<30的样本进行病毒的分离培养,共得到9个HAstV分离株。对这9个分离株进行了全基因组的测序及分析,以表征其遗传变异及进化特征。所有分离株经blastn比对后,发现其基因序列均与4型HAstV一致性最高。与HAstV-4原型株MK059952相比有较大变异,核苷酸一致性为88.15%~91.98%。重组分析发现9个分离株呈现出两种不同的进化重组方向。氨基酸置换熵值分析及选择压力分析发现有3个氨基酸位点同时满足易突变位点及适应性演化位点,这可能是HAstV能持续在全球流行的因素之一。本研究为南通地区流行的HAstV的遗传多样性和重组提供了进一步的证据,对HAstV引起相关疾病的预防控制将发挥重要作用。

Human astrovirus(HAstV)is a common pathogen causing acute gastroenteritis with global prevalence,mainly causing infection in young children,elderly and immunocompromised populations.In this study,712 stool specimens for monitoring acute gastroenteritis diarrhea in children<5 years old in outpatient and emergency clinics of sentinel surveillance hospitals in Nantong,China,were collected,and a total of 22cases were detected as positive for HAstV.The samples with Ct<30 were isolated and cultured for the virus,and a total of 9 HAstV isolates were obtained.The whole genome of these nine isolates was sequenced and analyzed to characterize their genetic variation and evolutionary features.All isolates were found to have the highest gene sequence identity with type 4 HAstV after blastn comparison.Compared with the prototype HAstV-4 strain MK059952,there was a large variation with nucleotide identity ranging from 88.15%to 91.98%.Recombination analysis revealed that the nine isolates showed two different evolutionary recombination directions.Amino acid substitution entropy analysis and selection pressure analysis revealed three amino acid sites that satisfied both mutation-prone sites and adaptation sites,which may be one of the factors for the continued global prevalence of HAstV.This study provides further evidence for the genetic diversity and recombination of HAstV prevalent in Nantong,China,which will play an important role in the preventive control of HAstV causing related diseases.