Lu Gang, Guo Wei, Qi Ting, Ma Jian, Zhao Shihua, Tian Zhige, Pan Jialiang, Zhu Chao, Wang Xiaojun, Xiang Wenhua
State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China.
Virus Genes. 2013 Oct;47(2):250-8. doi: 10.1007/s11262-013-0935-x. Epub 2013 Jun 19.
Amino acid and phylogenetic analysis showed that PB1-F2 of H7N7 and H3N8 equine influenza virus (EIV) evolved into two and nine clades, respectively. The PB1-F2 gene of H7N7 EIV strains isolated after 1973 was identified as being replaced by that of H3N8 EIV circulating simultaneously. All H7N7 EIV strains before 1973 contained PB1-F2 of 34 aa, while 90 aa after 1973. Meanwhile, most H3N8 EIV strains contained PB1-F2 of 90 or 81 aa. Evolutionary rate of PB1-F2 of H3N8 EIV was similar with that of PB1 in previous study. Meanwhile, PB1-F2 of H7N7 EIV evolved in significantly higher rate when compared with PB1-F2 of H3N8 EIV. Codon usage analysis revealed that PB1-F2 gene of EIV was less biased, which was identified as being determined by three main factors: mutational bias, selection pressure, and gene length. Our studies first in details report the genetic evolution, evolutionary rate, and the factors influencing codon usage bias of PB1-F2 of EIV.
氨基酸和系统发育分析表明，H7N7和H3N8马流感病毒（EIV）的PB1-F2分别进化为两个和九个分支。1973年后分离出的H7N7 EIV毒株的PB1-F2基因被确定已被同时流行的H3N8 EIV的基因所取代。1973年前的所有H7N7 EIV毒株都含有34个氨基酸的PB1-F2，而1973年后为90个氨基酸。同时，大多数H3N8 EIV毒株含有90或81个氨基酸的PB1-F2。H3N8 EIV的PB1-F2的进化速率与先前研究中PB1的进化速率相似。同时，与H3N8 EIV的PB1-F2相比，H7N7 EIV的PB1-F2进化速率明显更高。密码子使用分析表明，EIV的PB1-F2基因的偏向性较小，这被确定由三个主要因素决定：突变偏向、选择压力和基因长度。我们的研究首次详细报道了EIV的PB1-F2的遗传进化、进化速率以及影响密码子使用偏向的因素。
