Influenza A virus hemagglutinin H3N2 (HA (H3N2))

Influenza A virus hemagglutinin H3N2 is a homotrimeric glycoprotein present on the surface of the influenza A virus, subtype H3N2. It mediates the initial stages of viral infection by binding to sialic acid-containing receptors on host epithelial cells, primarily in the human respiratory tract[1][3][7]. Hemagglutinin is synthesized as an inactive precursor (HA0) which is cleaved by host proteases into HA1 (receptor-binding subunit) and HA2 (membrane fusion subunit)[3][5][7]. Upon endosomal acidification, HA undergoes conformational changes that drive fusion between the viral envelope and host endosomal membrane, allowing viral RNA entry into the host cytoplasm[1][3][5]. Hemagglutinin is the major antigen of the influenza virus, responsible for antigenic variation (drift/shift), and is a key target in vaccine and therapeutic antibody development[3][4][5]. The evolution of H3N2 HA influences viral transmissibility, severity, and immune recognition[4]. Neutralizing antibodies targeting HA can prevent virus binding or fusion, making it a principal target for influenza vaccines and therapeutic antibody development[1][6][7].

Other names

Hemagglutinin (H3N2)Influenza hemagglutinin H3H3N2 HA glycoproteinH3 hemagglutinin

Antibodies: Bind to receptor-binding domain or stem of HA to block sialic acid attachment or membrane fusion, preventing viral entry and neutralizing infectivity[1][6]. - Entry inhibitors: Block conformational changes required for fusion.