Codon Usage Bias Analysis Of Bluetongue Virus And Its Research In Phylogeography

Bluetongue virus(BTV)is a double stranded RNA virus that is twenty-hedron and it belongs to the genus Orbivirus within the family Reoviridae.BTV uses biting midges as a vector to infect mammals with a wide range of clinical signs.Despite significant progress in genomic analyses,still a viral relationship with different hosts affecting overall fitness,constancy,and dodging of hosts immune system are elusive.Here we analyzed BTV VP2 gene codon-based evolution,using 99 strains from different geographical locations,by computing several codon usage indices and applying multiple statistical methods.Nucleotide compositions and relative synonymous codon usage analysis showed that mutation bias and the A/U ending codons are predominant in BTV.Furthermore,the selection pressure from hosts on the BTV RSCU patterns highlighted the dominant effect compared with the vector.The group of similarity pattern suggests that the codon usage signature seems in between virus and vector instead of the hosts.The effective number of codons(ENC)indicated that the overall codon usage is slightly bias among all strains.Several lines of evidence support the hypothesis that a vital natural selection factor is shaping codon usage in this virus.However,mutational pressure and geographical realities cannot be ignored in marginal influence on codon usage.We believe that the current report first time describes the codon usage analysis in BTV VP2 genes.Such findings will assist researchers in understanding elements contribute to viral adaptation and evolutionary setup with hosts.Phylogeography can be used to study the principle and historical evolution of the existing geographical pattern from the phylogenetic perspective.By combining the information of genome and space time to explore the origin of organisms in the distribution of time and space,the evolution process and the history of biological evolution.At present,many research and application systems have been used to study the genetic evolution of virus in phylogeography.Therefore,systematic phylogeography will become a trend of genetic analysis of pathogenic bacteria in the future.In this study,the evolutionary history of 366 VP2 genes of bluetongue virus in 2000-2016 years was preliminarily studied by using Bayesian system in phylogeography.It was found that bluetongue virus at different time will produce different serotypes,BTV1 as the major serotype of bluetongue virus,has not been eliminated completely.In twenty-first Century,it is reproduced many times.The results suggested that BTV1 may provide the potential of new serotypes.In addition,Europe may be the root of widespread bluetongue virus since twenty-first Century.In addition to European countries,the United States in North America and India in southern Asia also play an important role in the spread of bluetongue virus.The results of this study laid a theoretical foundation for the evolution of bluetongue virus,and provided a theoretical basis for virus control and vaccine development.