Hemagglutinin (H5 influenza A) (H5HA)

Hemagglutinin (HA) is the primary surface glycoprotein of the H5 subtype of Influenza A virus, playing a critical role in the initial stages of viral infection [1, 10]. It functions as a homotrimeric class I fusion protein that mediates both the attachment of the virus to host cell sialic acid receptors and the subsequent fusion of the viral envelope with the host endosomal membrane [1, 5]. The H5 subtype, particularly H5N1, is notable for its high pathogenicity and the ability of its HA to be cleaved by a wide range of host proteases, which facilitates systemic infection beyond the respiratory tract [9, 10]. As the major target for the host immune response, H5 HA is the central component of avian influenza vaccines and a primary focus for the development of novel antiviral therapeutics [4, 6]. Therapeutic strategies include monoclonal antibodies such as CR6261 that target the conserved stalk region to prevent membrane fusion, as well as small molecules like Umifenovir that stabilize the pre-fusion conformation [5, 12]. Monitoring HA through sequence analysis and neutralization assays is essential for assessing pandemic risk and the efficacy of medical countermeasures [10, 15].

Other names

H5HAHemagglutinin H5H5N1 HemagglutininSurface glycoproteinInfluenza A virus H5 hemagglutinin

Inhibition of viral entry by blocking the binding of the hemagglutinin globular head to host sialic acid receptors or by preventing the pH-induced conformational change of the stalk region required for membrane fusion.