Genetic evidence of intercontinental movement of avian influenza in a migratory bird: the northern pintail (Anas acuta)

Abstract

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses confirmed the genetic divergence between Asian and North American strains of LPAI, but also suggested inter-continental virus exchange and at a higher frequency than previously documented. In 38 isolates from Alaska, nearly half (44.7%) had at least one gene segment more closely related to Asian than to North American strains of LPAI. Additionally, sequences of several Asian LPAI isolates from GenBank clustered more closely with North American northern pintail isolates than with other Asian origin viruses. Our data support the role of wild birds in the intercontinental transfer of influenza viruses, and reveal a higher degree of transfer in Alaska than elsewhere in North America.

Bridge hosts for avian influenza viruses at the wildlife/domestic interface: An eco-epidemiological framework implemented in southern Africa

“…In addition, phylogenetic analyses of LPAI indicated intercontinental movements of strains across waterfowl populations (Koehler et al, 2008). Therefore, understanding the role of wild birds in AIV epidemiology is of paramount importance to understand AIV strains' spread and emergence between wild and domestic avian populations (including the emergence of HPAI) (Caron et al, 2009).…”

Cross-Seasonal Patterns of Avian Influenza Virus in Breeding and Wintering Migratory Birds: A Flyway Perspective

“…Within this flyway the dispersal of AIV has potential public health risks. Of the four migratory flyways that encompass North America, the Pacific Flyway has the greatest potential for the introduction of the highly pathogenic AIV of the lethal H5N1 subtype by wild birds due to overlap with birds from Asia where outbreaks occur frequently (Winker et al 2007, Koehler et al 2008, Pearce et al 2009). Although trans-hemispheric gene flow appears to be relatively rare, invasion of a Eurasian subtype hemagglutinin gene has been documented within the Pacific Flyway.…”

Surveillance for High Pathogenicity Avian Influenza Virus in Wild Birds in the Pacific Flyway of the United States, 2006–2007

“…While HPAI H5N1 virus strains currently circulating in Asia and other parts of the world have not yet been detected in the Western Hemisphere, evidence of gene flow between Europe/Asia and North America of LPAI viruses supports the possibility of its introduction via migratory birds (21,28). Owing to the potential impact of this virus on the U.S. poultry industry as well as the potential that genetic changes in the virus could trigger a pandemic, the U.S. government developed and instituted in 2006 the U.S. Interagency Strategic Plan (U.S. Strategic Plan) for the early detection of HPAI H5N1 (43).…”