Phylogenetic Analysis of H6 Influenza Viruses Isolated from Rosy-Billed Pochards (Netta peposaca) in Argentina Reveals the Presence of Different HA Gene Clusters

Abstract

Until recently, influenza A viruses from wild waterfowl in South America were rarely isolated and/or characterized. To explore the ecology of influenza A viruses in this region, a long-term surveillance program was established in 2006 for resident and migratory water birds in Argentina. We report the characterization of 5 avian influenza viruses of the H6 hemagglutinin (HA) subtype isolated from rosy-billed pochards (Netta peposaca). Three of these viruses were paired to an N2 NA subtype, while the other two were of the N8 subtype. Genetic and phylogenetic analyses of the internal gene segments revealed a close relationship with influenza viruses from South America, forming a unique clade and supporting the notion of independent evolution from influenza A viruses in other latitudes. The presence of NS alleles A and B was also identified. The HA and NA genes formed unique clades separate from North American and Eurasian viruses, with the exception of the HA gene of one isolate, which was more closely related to the North American lineage, suggesting possible interactions between viruses of North American and South American lineages. Animal studies suggested that these Argentine H6 viruses could replicate and transmit inefficiently in chickens, indicating limited adaptation to poultry. Our results highlight the importance of continued influenza virus surveillance in wild birds of South America, especially considering the unique evolution of these viruses.

Migratory birds in southern Brazil are a source of multiple avian influenza virus subtypes

“…Rimondi et al13 reported the existence of a South American H6 influenza virus lineage in Argentinian aquatic birds in 2008; most of the Argentinian virus genes were phylogenetically distinct from those of the North American lineages and had probably evolved independently and in isolation. However, one of the sequenced NA genes appeared to be derived from a virus of North American lineage, indicating that viruses of the 2 American genetic lineages do have opportunities to interact 13…”

“…In South America, AIV has been confirmed in wild birds in multiple years in Argentina (H13N9, H1N1, H6N2, and H9N2),13, 39, 40 Bolivia (H7N3),41 (H7N3),42 Colombia (H5N2),19 Peru (H3N8, H4N5, H10N9, and H13N2),42, 43 and Brazil (H11N9) 20. However, the H6N1 subtype has not previously been identified in shorebirds.…”

“…AIVs in Eurasia and Australia appear to have diverged from those in North America, presumably as a result of different flyways being established and a consequent lack of contact between birds and therefore viruses, from the different continents 12. Similarly, the HA and NA genes of AIVs in Argentina differ from those of viruses circulating in North America and Eurasia 13. The main subtypes of AIV consistently reported to circulate in other countries14, 15, 16, 17, 18, 19 have not been reported in Brazil.…”

Avian Influenza in Wild Birds from South America: Review, Implications and Perspectives

“…13,14 In comparison, studies in South America have found an overall prevalence of 0.21% in Anseriformes (range: 0.25-0.86%) and 0.32% in Charadriiformes (range: 0.21-3.80%) (Table 3). 33,[35][36][37][38][39][40][41][42][43][44] It is worth noting that Mathieu et al stands out among South American studies for having found a slightly higher AIV prevalence (3.8%), which is probably related to the fact that this study investigated gulls that had been found dead, as opposed to actively capturing healthy birds in their natural habitat. 36 The reasons as to why South American wild birds appear to have a lower prevalence of AIV are unclear, and future studies will be necessary to confirm whether this is a widespread pattern and identify possible causes, or to dismiss the possibility that this reflects differences in sample collection season or storage.…”

<b>Vírus da influenza aviária:</b> monitoramento em aves de subsistência criadas no entorno de sítios de aves migratórias no Brasil

“…Na América do Sul, infecção pelo AIV subtipo H6 foi relatada na Argentina, a partir do isolamento do vírus de aves selvagens da espécie Netta peposaca (RIMONDI et al, 2011). Esta espécie, conhecida vulgarmente como marrecão, se reproduz no RS e nos países do Cone Sul e fora do período reprodutivo já foi observada nos estados de SP, RJ e MS (WIKIAVES, 2016).…”