Influenza A virus hemagglutinin H1 (HA (H1))

Influenza A virus hemagglutinin H1 is a trimeric glycoprotein present on the surface of the influenza A H1N1 virus, essential for viral infectivity and entry into host cells[1][4]. Each monomer of HA consists of two disulfide-linked subunits: HA1, which mediates receptor (sialic acid) binding on host respiratory epithelial cells, and HA2, whose fusion peptide facilitates the merger of viral and endosomal membranes in low pH environments[2][3][4]. This multi-domain structure allows HA to act as both an attachment and fusion protein. There are 18 HA subtypes, of which H1 is found in viruses infecting humans, most notably causing the 1918 and 2009 influenza pandemics[1][4]. HA is the principal antigenic determinant targeted by neutralizing antibodies and forms the basis for seasonal influenza vaccine composition[1][4]. Its rapid antigenic evolution, through both mutation and reassortment, presents continuing therapeutic and vaccine development challenges.

Other names

Hemagglutinin H1HA H1Influenza A hemagglutinin H1H1 hemagglutinin

Inhibition of receptor binding; Inhibition of conformational change or membrane fusion; Neutralization by antibody binding to HA1 head or HA2 stem