First isolation of an H1N1 avian influenza virus from wild terrestrial non-migratory birds in Argentina.

A type A avian influenza (AI) virus was isolated from dead or severely ill red-winged tinamous (Rhynchotus rufescens) found in a hunting ground in April 2008 in Argentina. The subtype of A/red-winged tinamou/Argentina/MP1/2008 was determined as H1N1 by sequence analysis. The cleavage site of the viral hemagglutinin corresponded to a low pathogenic influenza virus, although the clinical presentation and pathological studies suggest that the virus was pathogenic for red-winged tinamous. Phylogenetic analysis of the viral genome suggested that while the hemagglutinin and neuraminidase genes were related to AIV from North America, the internal genes were most closely related to other South American isolates. These findings support the postulated South American phylogenetic lineage for AIV PB2, PB1, PA, M and NS genes, and suggest that the evolutionary pathways of HA and NA genes involve exchanges between the Northern and Southern hemispheres.