Influenza A virus hemagglutinin (H1 subtype) (HA (H1))

Influenza A virus hemagglutinin (HA) is the primary surface glycoprotein of the influenza virus and the principal target for neutralizing antibodies and vaccine development [6, 24, 38]. The H1 subtype of HA is particularly significant as it has been responsible for major global health crises, including the 1918 "Spanish flu" and the 2009 "swine flu" pandemics, and continues to circulate as a seasonal influenza strain [8, 14, 25]. The term "H1B" in this context often refers to the 1B lineage of H1 viruses (human-seasonal-like viruses circulating in swine) or the H1b phylogenetic clade, which includes avian subtypes like H11, H13, and H16 [1, 6, 10, 15]. HA functions by binding to sialic acid receptors on the host cell surface to facilitate viral attachment and subsequently undergoes a conformational change in the endosome to mediate membrane fusion and viral entry [17, 25, 39]. Therapeutic interventions targeting H1 antigens include seasonal and pandemic vaccines, as well as broadly neutralizing monoclonal antibodies (bNAbs) that target the conserved stem region of the protein to provide cross-subtype protection [12, 15, 35, 42]. A major challenge in targeting H1 antigens is the virus's ability to undergo rapid antigenic drift and occasional antigenic shift, necessitating frequent vaccine updates and the development of "universal" influenza therapies [5, 13, 21, 38].

Other names

H1 HemagglutininH1 HAInfluenza A H1 antigenLineage 1B H1Clade H1bH1B influenza antigenHaemophilus influenzae type b

Neutralization of viral entry by blocking receptor binding or membrane fusion; induction of protective neutralizing antibodies and T-cell responses through vaccination.