Swine Influenza A Viruses and the Tangled Relationship with Humans
- Tavis K. Anderson1,
- Jennifer Chang1,
- Zebulun W. Arendsee1,
- Divya Venkatesh2,
- Carine K. Souza1,
- J. Brian Kimble1,
- Nicola S. Lewis2,
- C. Todd Davis3 and
- Amy L. Vincent1
- 1Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, Iowa 50010, USA
- 2Department of Pathology and Population Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
- 3Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA
- Correspondence: amy.vincent{at}usda.gov
Abstract
Influenza A viruses (IAVs) are the causative agents of one of the most important viral respiratory diseases in pigs and humans. Human and swine IAV are prone to interspecies transmission, leading to regular incursions from human to pig and vice versa. This bidirectional transmission of IAV has heavily influenced the evolutionary history of IAV in both species. Transmission of distinct human seasonal lineages to pigs, followed by sustained within-host transmission and rapid adaptation and evolution, represent a considerable challenge for pig health and production. Consequently, although only subtypes of H1N1, H1N2, and H3N2 are endemic in swine around the world, extensive diversity can be found in the hemagglutinin (HA) and neuraminidase (NA) genes, as well as the remaining six genes. We review the complicated global epidemiology of IAV in swine and the inextricably entangled implications for public health and influenza pandemic planning.
