Avian Influenza Viruses

Abstract

Avian influenza viruses comprise scores of antigenic subtypes within the genus Influenza A of the Orthomyxoviridae family. They are found most prominently in migratory waterfowl and shorebirds and are sporadically transmitted to other avian and mammalian species. The consequences of such transmissions can range from a subclinical infection to a highly infectious and lethal respiratory disease. Further, such transmissions may result in increased gene mutations or the transfer of avian virus genes into other circulating influenza gene pools or both.

Acquisition of a novel eleven amino acid insertion directly N-terminal to a tetrabasic cleavage site confers intracellular cleavage of an H7N7 influenza virus hemagglutinin

“…Khatchikian et al demonstrated that extensive passages of a LPAI H7N3 in the absence of trypsin resulted in acquisition of an 18-residue insertion at the cleavage site by recombination with ribosomal RNA (Khatchikian et al, 1989). Other events, such as recombination with the nucleoprotein (NP) or matrix (M) proteins, or polymerase slippage have occurred that resulted in the addition of amino acids adjacent to the HA cleavage site (Pasick et al, 2005, Perdue, 2001) (García et al, 1996). The equine H7 naturally acquired an insertion, most likely by recombination, and appears to have done so in horses.…”