Molecular Characteristic Of Rabies Virus And The Relationship With Epidemic And Distribution

Rabies is an ancient virulent disease of humans and animals, and more than50,000people die of rabies annual in the globle. China has the second higest number of rabies cases behind India, and rabies in China is a serious public health problem. The etiological agents of rabies is lyssavirus (LYSSA), which is an unsegmented, single-strand, negative strand RNA virus of Rhabdoviridae family. Currently, there are seven recognised genotypes (GT) of lyssavirus, and GT1(rabies virus, RABV) is responsible for classical rabies in terrestrial mammals globally and in bats on the American continent, as well as the cause of most rabies-related human deaths worldwide. Understanding the evolution of viruses can be a major step in fighting and controlling viral diseases. Therefore, we sequenced a whole genome of a human rabies virus vaccine strain of China (aG strain) and112G sequences of China street strains, and cited almost all the genome and G sequences of LYSSA to conduct the genome comparative analysis and of spatial and temporal dynamics of G gene. According to the analysis, we can understand the genetic and evolution characteristic of whole LYSSA, and especially illustrate the origin and spread of China rabies virus, for providing scientific basis for the effective prevention and control of China rabies.In this study, we sequenced the full-length genomic sequence of aG strain, a human rabies virus vaccine strain in China. The length of the complete aG genome was11925nt, and the genomic organization of aG, which is typical of all previously characterized RABV, is summarized as follows:a3’leader region of58nucleotides (1-58), the N gene (59-1482), P gene (1485-2476), M gene (2482-3284), G gene (3290-5356), L gene (5381-11855), and the5’trailer region of70nucleotides (11856-11925). The aG strain genome sequence has been compared to all street lyssavirus genomes as well as other typical vaccine strain genomes available from GenBank, and their lengths varied between11903nt and12278nt.3’UTR completely reserves in length (70nt), while the length of other non-coding regions are variable. The predicted size of the coding regions is similar among genotypes, with the M protein identical in length across all genotypes and the P protein the most variable. The percentage identity order N>L>M>G>P is reinforced by both intragenotypic and intergenotypic comparisons. These recognized and putative genotypes of LYSSA may be grouped3different phylogroups. The important functional sites of LYSSA genome seems more conserved in the same genotyoe than between different genotypes. In addention, we precidated the structure of the RABV entodomain first time, and we found the G303mutation between CTN181and street strain HN10may change the structure of Domain Ⅱ, which maybe related to the different of pathogenicity of them.We got112complete G sequences of Chinese samples from13provinces, and421G sequences from21specises in56countries were cited to analyse using BEAST(v1.6.1) and MigraPhyla(v1.0) softwares. The result showed that China street strains can be identified5groups:China I, distributing20provinces, was the most important epidemic group, and Hunan and Jiangsu may be the rabies spread centers of this group; China Ⅱ just circulated in China like China Ⅰ, and included ferret badger strains from Jiangxi and Zhejiang and some dog strains in South of China; China Ⅲ, from Yunnan and Guangxi, was close with Southesat Asia strains and maybe spread from Thailand; China Ⅳ was a part of Cosmopolitan clade of GT1, and maybe spread from India; China V only included Raccoon dog strains from Inner Mongolia, which closed with raccoon dog or dog strains in South Korea, and circulated in the Arctic-related clade of GT1. Spatial analysis showed that possible spread centers of Asia are Thailand and India.The mean rate of nucleotide substitution estimated for the G gene was3.01x10"4substitutions per site per year. Based on the substitution value, the TMRCA of all the LYSSA was estimated to be aproximatedly5030years, and other important TMRCA include2000,500, and200years, which well meet the important times of development of human civilization. So we precidated that migration frequent and activities extention of human may increase the diversity of LYSSA. Host switching in Lyssavirus history from the Chiroptera to the Carnivora orders was identified in our study.In this study, the genetic characteristic of LYSSA different genotypes or phylogroups were analysed, and, for the first time, based on the precidated RABV G structure, we explored the amino acid sites related on virulence of vaccine and street strains. Different RABV groups in China were identified based on rich G sequence data, and possible origin and spread direction of every group were speculated. According to the migration analysis of Asia RABV, we first reported that Thailand and India maybe the spread centers of Asia RABV. In addition, the nature evolutionary history of global LYSSA were described. All these results were important for scientific and effective prevention and control of rabies.