Influenza A virus hemagglutinin H5 (H5 HA) (H5 HA)

Influenza A virus hemagglutinin H5 is a major surface glycoprotein found on H5 subtype influenza viruses, including the highly pathogenic H5N1 strain. It functions as a class I viral fusion protein and a lectin, mediating the initial attachment of the virus to host cell sialic acid receptors (UniProt: P03452). Following endocytosis, a pH-triggered conformational change in the HA protein facilitates the fusion of the viral envelope with the endosomal membrane, allowing the viral genome to enter the cytoplasm (PubMed: 19246614). As the primary target for neutralizing antibodies, H5 HA is the essential component of vaccines like Audenz and Prepandrix designed to prevent avian influenza and mitigate pandemic threats (FDA, 2020; EMA, 2008). Therapeutic research also focuses on broadly neutralizing monoclonal antibodies, such as CR6261 and MEDI8852, which target the conserved stem region of the HA molecule to provide cross-strain protection (Science, 2016). The high rate of mutation in the HA gene, known as antigenic drift, poses a significant challenge for long-term vaccine efficacy and necessitates continuous global surveillance (WHO, 2023). Understanding the structural biology of H5 HA is critical for developing next-generation universal influenza vaccines and effective antiviral strategies.

Other names

H5HA5Hemagglutinin subtype 5H5N1 hemagglutininInfluenza A H5 antigen

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