Hemagglutinin (Influenza A virus H3N2) (HA)

Hemagglutinin (HA) is the primary surface glycoprotein of the Influenza A virus H3N2 subtype, playing a dual role in viral infection. It first mediates the attachment of the virus to host cells by binding to terminal sialic acid residues on cell surface glycoproteins and glycolipids (UniProt, 2017; Wikipedia, 2024). Following endocytosis, the acidic environment of the endosome triggers a dramatic conformational change in the HA protein, specifically the HA2 subunit, which facilitates the fusion of the viral envelope with the endosomal membrane, releasing the viral genome into the cytoplasm (NIH, 2024; Wikipedia, 2024). As the major antigen on the viral surface, HA is the primary target for seasonal influenza vaccines and the focus of efforts to develop universal vaccines (MDPI, 2020; NIH, 2024). Therapeutic strategies targeting HA include small molecule fusion inhibitors like umifenovir (Arbidol) and broadly neutralizing monoclonal antibodies that target the conserved stem region to prevent membrane fusion (ASM, 2019; Exploration Pub, 2023). However, the protein's high rate of antigenic drift and the potential for egg-adaptive mutations during vaccine manufacturing present significant challenges for maintaining long-term therapeutic efficacy (MDPI, 2020; NIH, 2024).

Other names

H3 HAH3N2 HemagglutininHA1/HA2Viral hemagglutininHemagglutinin protein

Inhibition of viral-host membrane fusion by stabilizing the prefusion conformation or blocking the conformational change required for fusion; blocking of viral attachment to host cells by interfering with sialic acid receptor binding (ASM, 2019; Exploration Pub, 2023; PatSnap, 2024).