One of the most significant and challenging features of influenza A virus (IAV) is its ability to rapidly change to escape immunity or adapt to a new host.
IAVs are divided into subtypes on the basis of differences between the two proteins that project from the surface of the virus, the haemagglutinin (HA) and the neuraminidase (NA). There are 18 known HA subtypes (H1–H18) and 11 NA subtypes (N1–N11), which can occur in many different combinations (e.g. H5N1 or H5N8).
Most known subtypes of IAV can be found in ducks, which generally don’t become sick as a result of infection and are regarded as the reservoir host. Occasionally, particular subtypes jump into other species where they become established and cause disease (such as H1N1 and H3N2 viruses, currently circulating in people). Two subtypes (H17N10 and H18N11) were also recently discovered in bats.
The disease caused depends what species is infected. However some subtypes, like H5 and H7, can gain the ability to cause very severe disease (when they become known as highly pathogenic avian influenza).
Here in the One Virology Research Group, we’re developing important new work on both avian and equine influenza strains.