Evidence of a fixed internal gene constellation in influenza A viruses isolated from wild birds in Argentina (2006–2016)

Wild aquatic birds are the major reservoir of influenza A virus. Cloacal swabs and feces samples (n = 6595) were collected from 62 bird species in Argentina from 2006 to 2016 and screened for influenza A virus. Full genome sequencing of 15 influenza isolates from 6 waterfowl species revealed subtypes combinations that were previously described in South America (H1N1, H4N2, H4N6 (n = 3), H5N3, H6N2 (n = 4), and H10N7 (n = 2)), and new ones not previously identified in the region (H4N8, H7N7 and H7N9). Notably, the internal gene segments of all 15 Argentine isolates belonged to the South American lineage, showing a divergent evolution of these viruses in the Southern Hemisphere. Time-scaled phylogenies indicated that South American gene segments diverged between ~ 30 and ~ 140 years ago from the most closely related influenza lineages, which include the avian North American (PB1, HA, NA, MP, and NS-B) and Eurasian lineage (PB2), and the equine H3N8 lineage (PA, NP, and NS-A). Phylogenetic analyses of the hemagglutinin and neuraminidase gene segments of the H4, H6, and N8 subtypes revealed recent introductions and reassortment between viruses from the Northern and Southern Hemispheres in the Americas. Remarkably and despite evidence of recent hemagglutinin and neuraminidase subtype introductions, the phylogenetic composition of internal gene constellation of these influenza A viruses has remained unchanged. Considering the extended time and the number of sampled species of the current study, and the paucity of previously available data, our results contribute to a better understanding of the ecology and evolution of influenza virus in South America.

Instituto de Virología

Fil: Rimondi, Agustina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología; Argentina

Fil: Gonzalez Reiche, Ana Silvia. University of Georgia. College of Veterinary Medicine. Poultry Diagnostic and Research Center; Estados Unidos. Icahn School of Medicine at Mount Sinai. Department of Genetics and Genomic Sciences; Estados Unidos

Fil: Olivera, Valeria Soledad. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología; Argentina

Fil: Decarre, Julieta. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; Argentina

Fil: Castresana, Gabriel Julián. Buenos Aires. Organismo Provincial para el Desarrollo Sostenible. Dirección de Áreas Naturales Protegidas; Argentina

Fil: Romano, Marcelo. Centro de Investigaciones en Biodiversidad y Ambiente, Rosario; Argentina

Fil: Nelson, Martha I. National Institutes of Health. Fogarty International Center; Estados Unidos

Fil: van Bakel, Harm. Icahn School of Medicine at Mount Sinai. Department of Genetics and Genomic Sciences; Estados Unidos

Fil: Pereda, Ariel Julian. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología; Argentina

Fil: Ferreri, Lucas. University of Georgia. College of Veterinary Medicine. Diagnostic and Research Center; Estados Unidos

Fil: Geiger, Ginger. University of Georgia. College of Veterinary Medicine. Poultry Diagnostic and Research Center; Estados Unidos

Fil: Perez, Daniel Roberto. University of Georgia. College of Veterinary Medicine. Poultry Diagnostic and Research Center; Estados Unidos