Influenza A virus hemagglutinin H1 subtype (HA (H1 subtype))

Influenza A virus hemagglutinin H1 subtype is a surface glycoprotein found on the envelope of H1N1 influenza A viruses[5][1][3]. It is responsible for binding to sialic acid-containing receptors on the surface of host epithelial cells, mediating viral attachment and entry via receptor-binding and subsequent fusion of the viral and host membranes[1][5][3][7]. The HA protein is a homotrimer, with each subunit consisting of a globular head (receptor binding) and a stem domain (fusion machinery)[1][3][7]. The structure and antigenic sites of HA are the principal targets of host neutralizing antibodies and inform vaccine design[2][1][7]. Mutations in HA are key drivers of antigenic evolution (drift), immune evasion, and viral adaptation, and the H1N1 subtype has caused several pandemics in the past century, most notably in 1918 and 2009[6][4]. HA is both a diagnostic marker and a critical target for antiviral and vaccine strategies against influenza A H1N1 infection[1][5][8].

Other names

Influenza hemagglutinin H1H1 hemagglutininH1N1 HAInfluenza A(H1N1) hemagglutinin

Viral entry inhibitor (theoretical small molecules or antibodies: block receptor binding/fusion); Neutralization by vaccine-elicited or monoclonal antibodies (bind HA to prevent interaction with host cells and/or inhibit structural rearrangements needed for membrane fusion)