title: Evolution of the viral hemorrhagic septicemia virus: divergence, selection and origin.
abstract: Viral hemorrhagic septicemia virus (VHSV) is an economically significant rhabdovirus that affects an increasing number of freshwater and marine fish species. Extensive studies have been conducted on the molecular epizootiology, genetic diversity, and phylogeny of VHSV. However, there are discrepancies between the reported estimates of the nucleotide substitution rate for the G gene and the divergence times for the genotypes. Herein, Bayesian coalescent analyses were conducted to the time-stamped entire coding sequences of the six VHSV genes. Rate estimates based on the G gene indicated that the marine genotypes/subtypes might not all evolve slower than their major European freshwater counterpart. Age calculations on the six genes revealed that the first bifurcation event of the analyzed isolates might have taken place within the last 300 years, which was much younger than previously thought. Selection analyses suggested that two codons of the G gene might be positively selected. Surveys of codon usage bias showed that the P, M and NV genes exhibited genotype-specific variations. Furthermore, we proposed that VHSV originated from the Pacific Northwest of North America.
authors.affiliation: College of Life Science, Northeast Forestry University, Harbin 150040, China.
authors.forename: Mei
authors.initials: M
authors.lastname: He
authors.affiliation: Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China.
authors.forename: Xue-Chun
authors.initials: XC
authors.lastname: Yan
authors.affiliation: College of Life Science, Northeast Forestry University, Harbin 150040, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China.
authors.forename: Xiao-Wen
authors.initials: XW
authors.lastname: Sun
authors.affiliation: College of Life Science, Northeast Forestry University, Harbin 150040, China. Electronic address: chunboteng@nefu.edu.cn.
authors.forename: Chun-Bo
authors.initials: CB
authors.lastname: Teng
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D003062:Codon; D014644:Genetic Variation; D005838:Genotype; D029141:Novirhabdovirus / Q000235:genetics*; D010802:Phylogeny; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D003062:Codon
keywords: Divergence; Substitution rate; TMRCA; VHSV