一株新型鼠类星状病毒的基因组特点和进化分析

Genomic characteristics and phylogenetic analysis of a novel rat astrovirus strain

目的研究一株新型鼠类星状病毒的基因组特点和进化关系。方法采集221只山东省鼠类肠道内容物,采用高通量测序方法进行病毒组研究。结果发现一株新型星状病毒,并获得该病毒接近全长基因组,命名为RoAstV/CHN/S3。RoAstV/CHN/S3具有典型的星状病毒基因组结构,相似性分析表明与啮齿类动物星状病毒和猪星状病毒4型关系最为相近。ORF2的氨基酸遗传距离结果显示,RoAstV/CHN/S3与啮齿类动物和猪星状病毒4型的遗传距离为0.557~0.655,哺乳星状病毒属内种之间的遗传距离为0.338~0.783,推断其可能为新种。根据ORF1a、ORF1b和ORF2的系统发育树结果,RoAstV/CHN/S3与啮齿类动物星状病毒、猪星状病毒4型聚为一簇,表明这些啮齿类动物星状病毒和猪星状病毒4型具有共同祖先,也提示潜在的祖先跨种传播。对221只鼠类的肠道内容物筛查结果显示,4只鼠类为阳性,阳性率为1.8%,其中3只为褐家鼠,1只为黑线姬鼠,均来自山东省济宁市。结论新型星状病毒RoAstV/CHN/S3的发现丰富了星状病毒的多样性,为新发突发传染病的防控提供了重要的数据信息。

Objective To inverstigate the genome characteristics of a novel astrovirus strain and to analyze its phylogenetic relationship with known virus.Methods A total of 221 rat intestinal content samples were collected in Shandong province.High throughput sequencing method was used to study the viral genomes.Results A novel astrovirus strain was discovered and a nearly complete genome was obtained.The strain was named as RoAstV/CHN/S3.RoAstV/CHN/S3 showed typical genomic structure of astrovirus.The similarity analysis showed that RoAstV/CHN/S3 was the most closely related to rodent astrovirus and porcine astrovirus 4.The results of genetic distance by amino acids in ORF2 showed that the genetic distances of RoAstV/CHN/S3 to rodent astrovirus and porcine astrovirus 4 were 0.557-0.655.Since the genetic distances of species in mammalian astrovirus was 0.338-0.783,RoAstV/CHN/S3 should be classified as novel species.The result of phylogenetic tree for ORF1a,ORF1b and ORF2 showed that RoAstV/CHN/S3 was clustered with rodent astroviruses and porcine astrovirus 4,suggesting these viruses shared potential common ancestor and potential cross-species transmission.The screen results to 221 intestinal content samples showed that 4 samples were positive and the positive rate was 1.8%.Three of the 4 rats were sewer rat while the rest one was striped field mouse.All these samples were from the Jining city of Shandong province.Conclusions The discovery of RoAstV/CHN/S3 has expand the diversity of astroviruses and provided the important information to control and prevent emerging infectious disease in the future.