Hemagglutinin of influenza A virus subtype H1N1 (HA (H1N1))

Hemagglutinin of influenza A virus subtype H1N1 is a trimeric, class I viral envelope glycoprotein that mediates the attachment of the influenza virus to sialic acid-containing receptors on the surface of host respiratory epithelial cells, initiating infection[1][3][4][5]. It is synthesized as an inactive precursor (HA0), which is cleaved by host proteases into HA1 and HA2 subunits, enabling membrane fusion upon acidification in the endosome. HA is the primary target for neutralizing antibodies and the main antigenic component used in influenza vaccines, as well as a critical determinant of host range, transmissibility, and pandemic potential[1][2][3][4][5]. It is also a key target for antibody therapeutics and experimental antiviral agents. Due to its high mutation rate, hemagglutinin displays significant antigenic drift and shift, complicating vaccine efficacy and necessitating frequent updates to vaccine formulations[1][3][5].

Other names

Influenza A virus hemagglutinin H1N1HA protein (H1N1)H1 hemagglutininInfluenza hemagglutinin H1

Antibodies: Block viral attachment by binding to HA’s receptor-binding domain or stem, neutralizing infectivity and preventing membrane fusion[1][3][5]. Entry inhibitors: Prevent HA conformational change or membrane fusion. Vaccines: Induce immune response (especially neutralizing antibody production) against HA to prevent infection[1][5]. Other