羊轮状病毒NT株VP1基因的测序和分子进化分析

Sequence and evolutionary analysis of VP1 gene of Ovine rotavirus NT

摘要:

摘要：【目的】为了研究羊轮状病毒NT株VP1基因的遗传进化规律，【方法】根据GenBank中相关VP1基因的保守序列，设计合成引物，扩增NT株VP1基因并进行克隆测序和序列分析。【结果】 氨基酸序列比较表明NT株与其他毒株VP1基因的相似性为77.3%～98.4%，且氨基酸突变多发生在VP1蛋白的非功能区。VP1蛋白进化树表明NT株与牛轮状病毒处于同一进化分支，有较近的亲缘关系。结合26株具有代表性的轮状病毒，计算毒株间VP1基因的核苷酸和氨基酸进化距离，并对核苷酸的同义突变率（dS）和非同义突变率（dN）进行研究，发现dN/dS的比值小于1，说明同义替代是VP1基因在进化过程中的主要变异。【结论】本文首次对羊轮状病毒NT株进行了VP1基因的测序，并对VP1基因的进化距离和进化规律进行深入探讨。

Abstract:

Abstract: [Objective] The ovine rotavirus strain NT isolated from diarrhea lamb in China was considered as a promising vaccine strain. Based on the VP1 gene was one of the important structural proteins of rotavirus, we studied on the evolutional characteristics of VP1. [Methods] According to the published conservative sequences of VP1 genes, we designed a pair of specific primers for cloning and sequencing of VP1 gene. [Results] Sequencing result showed that the VP1 gene was 3,302 bp in length and the deduced protein was 1,088 aa. Comparison of amino acid sequences revealed that the ORV-NT shared 77.3% - 98.4% similarities with other group A rotaviruses. Furthermore, sequence alignment analysis manifested that amino acid variations mainly occurred in the non-functional regions of VP1 protein. Phylogenetic analysis of VP1 protein showed that the OVR-NT was grouped in the bovine rotavirus clusters, indicating a closer relationship between them. Evolutionary distance of nucleotide sequence and amino acid sequence among VP1 genes of different rotaviruses were calculated, respectively. Analysis of synonymous mutation rate and Non-synonymous mutation rate demonstrated that synonymous substitution was the major pattern of variation in the process of evolution. [Conclusion] This was the first report on sequencing and evolutionary distance analysis of VP1 gene of ORV-NT.