Suzuki Yoshiyuki
Center for Information Biology and DNA Data Bank of Japan, National Institute of Genetics, 1111 Yata, Mishima-shi, Shizuoka-ken 411-8540, Japan.
Gene. 2008 Dec 31;427(1-2):111-6. doi: 10.1016/j.gene.2008.09.012. Epub 2008 Sep 20.
It has been proposed that antigenic evolution of hemagglutinin 1 (HA1) for H3N2 human influenza A virus was punctuated. In the population genetic analysis, however, it was controversial whether positive selection operated on HA1 in a punctuated manner for the branches of the phylogenetic tree where transitions to new antigenic clusters occurred (C branches), or continuously. In the molecular evolutionary analysis, positive selection was detected for the trunk (T) branches but the relationship between antigenic evolution and positive selection was unclear. Here molecular evolutionary analysis was conducted to examine natural selection operating on HA1 of H3N2 human influenza A virus by dividing HA1 into epitopes A-E and other sites, as well as dividing the phylogenetic tree into the C branches overlapping with the T branches (C-T branches), those not overlapping with the T branches (C-NT branches), the T branches not overlapping with the C branches (NC-T branches), and other branches (NC-NT branches). Positive selection was detected for C, T, and NC-T branches, whereas evolution for the NC-NT branches appeared to be mainly neutral. Positive selection appeared to have operated throughout the trunk, which covered the entire time period of the phylogenetic tree, suggesting that positive selection operated continuously on HA1 during evolution of H3N2 human influenza A virus.
有人提出，H3N2甲型流感病毒血凝素1（HA1）的抗原进化是间断性的。然而，在群体遗传分析中，对于在系统发育树中发生向新抗原簇转变的分支（C分支），正向选择是否以间断的方式作用于HA1，还是持续作用，存在争议。在分子进化分析中，在主干（T）分支中检测到正向选择，但抗原进化与正向选择之间的关系尚不清楚。在此进行分子进化分析，通过将HA1分为A - E表位和其他位点，以及将系统发育树分为与T分支重叠的C分支（C - T分支）、不与T分支重叠的C分支（C - NT分支）、不与C分支重叠的T分支（NC - T分支）和其他分支（NC - NT分支），来研究作用于H3N2甲型流感病毒HA1的自然选择。在C、T和NC - T分支中检测到正向选择，而NC - NT分支的进化似乎主要是中性的。正向选择似乎在整个主干中起作用，主干覆盖了系统发育树的整个时间段，这表明在H3N2甲型流感病毒进化过程中，正向选择持续作用于HA1。
