Influenza A virus

Influenza A virus (IAV) is a pathogen that causes the flu in birds and some mammals, including humans. It is an RNA virus whose subtypes have been isolated from wild birds. Occasionally, it is transmitted from wild to domestic birds, and this may cause severe disease, outbreaks, or human influenza pandemics.

Each virus subtype includes a wide variety of strains with differing pathogenic profiles; some may cause disease only in one species but others to multiple ones. Because the viral genome is segmented, subtypes are neither strains nor lineages, as the subtype designation refers to proteins encoded by only two of the eight genome segments.

A filtered and purified influenza A vaccine for humans has been developed and many countries have stockpiled it to allow a quick administration to the population in the event of an avian influenza pandemic. In 2011, researchers reported the discovery of an antibody effective against all types of the influenza A virus.