Characterization of a Novel Influenza A Virus Hemagglutinin Subtype (H16) Obtained from Black-Headed Gulls

Abstract

In wild aquatic birds and poultry around the world, influenza A viruses carrying 15 antigenic subtypes of hemagglutinin (HA) and 9 antigenic subtypes of neuraminidase (NA) have been described. Here we describe a previously unidentified antigenic subtype of HA (H16), detected in viruses circulating in black-headed gulls in Sweden. In agreement with established criteria for the definition of antigenic subtypes, hemagglutination inhibition assays and immunodiffusion assays failed to detect specific reactivity between H16 and the previously described subtypes H1 to H15. Genetically, H16 HA was found to be distantly related to H13 HA, a subtype also detected exclusively in shorebirds, and the amino acid composition of the putative receptorbinding site of H13 and H16 HAs was found to be distinct from that in HA subtypes circulating in ducks and geese. The H16 viruses contained NA genes that were similar to those of other Eurasian shorebirds but genetically distinct from N3 genes detected in other birds and geographical locations. The European gull viruses were further distinguishable from other influenza A viruses based on their PB2, NP, and NS genes. Gaining information on the full spectrum of avian influenza A viruses and creating reagents for their detection and identification will remain an important task for influenza surveillance, outbreak control, and animal and public health. We propose that sequence analyses of HA and NA genes of influenza A viruses be used for the rapid identification of existing and novel HA and NA subtypes.

A bivalent influenza VLP vaccine confers complete inhibition of virus replication in lungs

“…Influenza viruses present in birds continue to be a source for a diverse combination of antigenic subtypes including 16 hemagglutinin (HA) and 9 neuraminidase (NA) and represent a large reservoir of novel antigens to which the human population is naïve [1,2]. Chemically inactivated whole influenza A and B virus vaccines, or detergentsplit virus vaccines have been extensively used in humans.…”

Avian Influenza among Waterfowl Hunters and Wildlife Professionals

“…Wild ducks, geese, and shorebirds are the natural reservoir for influenza A virus ( 1 ); all 16 hemagglutinin (H) and 9 neuraminidase (N) subtypes are found in these wild birds ( 1 , 2 ). Recently, the rapid spread of influenza A/H5N1 virus to new geographic regions, possibly by migrating waterfowl, has caused concern among public health officials who fear an influenza pandemic.…”

Epidemiological update on swine influenza (H1N1) in pigs

“…The virus is further classifi ed into subtypes based on the antigenic properties of the external glycoproteins hemagglutinin (HA) and neuraminidase (NA). Depending on the antigenicity of these two envelope spikes, infl uenza A viruses are categorized into 16 H (H1-H16) and nine N (N1-N9) groups, and their combination designates the subtype of the virus [5]. To date, 105 infl uenza A virus subtypes have been identifi ed, all of which are endemic in water birds.…”