Influenza A virus H7N9 hemagglutinin (HA) (HA)

Influenza A virus H7N9 hemagglutinin (HA) is a primary surface glycoprotein and a critical mediator of viral entry into host cells [11, 12]. It is a homotrimeric class I fusion protein composed of two subunits: HA1, which facilitates binding to sialic acid receptors on the host cell surface, and HA2, which mediates the fusion of the viral envelope with the endosomal membrane following internalization [11, 13]. The H7N9 subtype is of significant clinical concern due to its high pathogenicity in humans, often resulting in severe respiratory distress and a high case-fatality rate, as well as its potential to cause a global pandemic [17, 21]. As the major target of the host immune response, HA is the central component of both inactivated and recombinant vaccines designed to elicit protective neutralizing antibodies [19, 20]. Therapeutic strategies targeting HA include broadly neutralizing monoclonal antibodies, such as MEDI8852 and CR9114, which bind to conserved epitopes in the HA head or stalk to prevent viral attachment or fusion [9, 10]. Additionally, small-molecule inhibitors like Umifenovir (Arbidol) target the HA-mediated fusion process to block viral entry [13]. However, the effectiveness of these interventions is continually challenged by the virus's rapid antigenic drift and the inherently low immunogenicity of the H7 HA protein [6, 15].

Other names

H7 HAH7N9 HAHemagglutinin proteinHA1 subunitHA2 subunitH7N9 hemagglutinin antigen

Neutralization of viral infectivity by blocking attachment to host sialic acid receptors or inhibiting pH-dependent membrane fusion.