Influenza A virus group 1 hemagglutinin (HA)

Influenza A virus group 1 hemagglutinin (HA) is a critical surface glycoprotein that mediates viral entry into host cells by binding to sialic acid receptors and facilitating membrane fusion (Skehel & Wiley, 2000). It is a trimeric protein composed of two subunits: HA1, which forms the distal globular head containing the receptor-binding site, and HA2, which forms the proximal stem region responsible for fusion (UniProt P03452). Group 1 HA encompasses several subtypes, including H1, H2, H5, and H9, which are significant drivers of seasonal and pandemic influenza. Therapeutic agents like CF-401 are monoclonal antibodies designed to target the highly conserved HA2 stem region rather than the rapidly mutating HA1 head (ContraFect Corp, 2017). By binding to this conserved epitope, these drugs inhibit the structural rearrangements necessary for the fusion of the viral and endosomal membranes, effectively neutralizing a broad range of Group 1 influenza strains (Throsby et al., 2008). This strategy aims to provide more durable and broad-spectrum protection compared to traditional vaccines that target the variable head region (Nature Communications, 2018).

Other names

HemagglutininInfluenza A HAGroup 1 HAHA1/HA2 complexViral surface glycoproteinInfluenza A virus group 1 hemagglutinin – CF-401

Binding to the highly conserved stem region (HA2 subunit) of the hemagglutinin protein to sterically inhibit the pH-dependent conformational change required for the fusion of the viral envelope with the host cell endosomal membrane (PubMed: 19079061; ContraFect Corp, 2017).