Publication / Source: Infectious Diseases Hub
Authors: Janet M Daly (School of Veterinary Medicine and Science, University of Nottingham, UK)
Avian reservoir of influenza A virus subtypes
Influenza A viruses (IAVs) infect a broad range of species (from bats and birds to pigs and people), but waterfowl are regarded as the main reservoir species . IAVs are classified into subtypes on the basis of the two proteins that project from the virus particle, hemagglutinin (HA) and neuraminidase (NA). There are currently 18 known HA subtypes (H1 to H18) and 11 NA subtypes (N1 to N11).
Until the recent identification of two novel subtypes in bats (H17N10 and H18N11 ), all known HA and NA subtypes had been identified in birds in 117 of the 144 possible combinations of H1–H16 and N1–N9 . Occasionally, spill-over events occur and certain subtypes have subsequently adapted to and become established in mammalian hosts (e.g. H3N2 and H1N1 in people and H3N8 in horses). The mechanisms that allow IAVs to jump from one host species to another are still not fully understood.