Review: molecular evolution and the feasibility of an avian influenza virus becoming a pandemic strain--a conceptual shift.

摘要

During recent years, a conceptual shift took place with respect to the genetic dynamics of influenza A viruses. In difference of the widely accepted approach that avian viral strains have the capacity to infect man only after undergoing genetic reassortment within pigs, it is now contended that direct transfection of man by intact avian-harbored viral genotypes is an actual, recurrent move, which may bring bout the generation of a new pandemic strain. This cardinal conceptual shift has been propelled by the appearance in 1997 of the zoonotic avian influenza H5N1 virus--a virulent, not yet contagious strain for humans--and ostensibly followed a genuine, unprecedented path within the evolutionary paradigm of Influenza A virus. This paper suggests that direct avian-human genetic interface is a pristine fundamental within the natural history of this protean pathogen, points at earlier as well as corroborative findings leading to such postulation, and regards the course of the H5N1 virus (and alike), as a readily detectable and traceable one, presently, rather then a novel development It further examines the general feasibility of various components of that interface at large, such that give rise--whether gradually or abruptly--to pandemic genotypes, in terms of infectivity, pathogenicity and contagiousness. Within that context, the anticipated involvement of certain human-adapted antigenic subtypes is referred to, extrapolatively. Connectedly, the significance of natural ice as plausible regenerator of influenza A viruses, and its possible contribution to the emergence and reemergence of pandemic strains are accentuated.