Influenza virus hemagglutinin protein, H2 subtype (HA (H2 subtype))

Influenza virus hemagglutinin protein, H2 subtype is a major surface glycoprotein of influenza A viruses responsible for viral entry into host cells through binding to sialic acid-containing receptors and mediating membrane fusion at low pH[1][3][4][5][6][7]. It consists of a homotrimer, each monomer containing an HA1 subunit (responsible for receptor binding) and HA2 subunit (mediates membrane fusion), generated by cleavage of the precursor HA0. The H2 subtype triggered the 1957–1968 "Asian flu" pandemic and remains a pandemic threat as it circulates in avian and swine reservoirs[1][3][5][6]. Hemagglutinin is the principal target for neutralizing antibodies elicited by infection or vaccination, and mutations in its structure facilitate antigenic drift and host specificity shifts. Despite not being the direct target of most approved small-molecule antivirals, it is the molecular target for monoclonal antibody therapeutics and the critical antigen for all current influenza vaccine strategies[1][3][4][6][7].

Other names

Hemagglutinin H2HA H2H2 HAInfluenza A virus hemagglutinin H2H2N2 hemagglutininAsian flu hemagglutininInfluenza A HA H2

Neutralizing antibodies bind hemagglutinin, blocking receptor binding or fusion[4][6][7]. Vaccines induce protective antibodies against hemagglutinin head or stem region[4][6][7]. Host protease inhibition (experimental: protecting against activation cleavage)[4].