[A phylogenetic analysis of genes of the influenza virus. Phylogenetic trees and fixation rates].

The phylogenetic trees of influenza virus genes of hemagglutinins, neuraminidases, and of NS genes were composed. Considering properties of synonimic replacements to be neutral and their rates constant at each tree, the dates of ancestor branch points were calculated, and the rates of fixation of synonimic (Ks) and non-synonimic (Kns) replacements estimated. The epidemic branches were mostly shown to be "deadlocks", non-epidemic ones being internal or "roots." The ratios of the numbers of synonimic to non-synonimic replacements (vs/vns) were correspondingly 1.32+/-0.42 and 4.78+/-1.28 for all trees, the difference being significant. It was shown that the dated branch points for hemagglutinins are non-randomly clustered around the initial points of the main genetic shifts of the A-type virus, corresponding to the influenza pandemics. It seems that these ancestor forms of virus behave similar to the "train" of these shifts, reproducing together with the pandemic forms under conditions of decreased immune resistance of host population. The rates of fixation of non-synonimic replacements in the epidemic branches of this tree are 4 times increased, as compared to non-epidemic ones.