Hemagglutinin H5 (H5 HA) (H5 HA)

Hemagglutinin H5 is a critical surface glycoprotein found on the envelope of Influenza A virus subtypes, most notably the highly pathogenic H5N1 avian influenza. It functions as a homotrimeric lectin that mediates the initial stages of viral infection by binding to sialic acid receptors on the host cell surface [1]. The H5 subtype typically exhibits a preference for alpha-2,3-linked sialic acids, which are prevalent in the respiratory tracts of birds, though mutations can increase affinity for human-type alpha-2,6 receptors [2]. Following endocytosis, a pH-triggered conformational change in the HA2 subunit facilitates the fusion of the viral and endosomal membranes, releasing the viral ribonucleoproteins into the host cytoplasm [3]. As the primary antigen on the viral surface, H5 HA is the central component of pandemic preparedness vaccines and the target of neutralizing antibody responses [4]. Therapeutic strategies include the development of monoclonal antibodies that bind to the conserved stem region of the protein to inhibit the fusion process across multiple influenza strains [5].

Other names

H5HA5Hemagglutinin subtype H5H5N1 hemagglutininInfluenza A virus H5 hemagglutinin

Neutralization of viral entry by blocking the receptor-binding site or inhibiting pH-dependent membrane fusion.