Influenza virus hemagglutinin receptor-binding site (HA RBS)

Influenza virus hemagglutinin (HA) is a trimeric surface glycoprotein essential for the viral life cycle, specifically mediating attachment and entry into host cells (UniProt: P03437). The receptor-binding site (RBS) is a shallow pocket located on the distal globular head of the HA1 subunit, which specifically recognizes and binds to sialic acid residues on host cell surface glycoproteins and glycolipids (PubMed: 24108442). This interaction is the primary determinant of host range and tissue tropism, with human influenza viruses typically preferring α2,6-linked sialic acids found in the upper respiratory tract (NIH: PMC3563341). As the most prominent surface antigen, the HA globular head is the primary target for the host's neutralizing antibody response following infection or vaccination. However, the RBS and surrounding regions are subject to frequent mutations, a process known as antigenic drift, which allows the virus to escape pre-existing immunity and necessitates regular updates to seasonal vaccines (CDC: Antigenic Drift). Therapeutic strategies targeting the RBS include monoclonal antibodies like VIS410 and MHAA4549A, which are designed to block viral attachment and prevent the initiation of the infection cycle (PubMed: 29439963). Additionally, small molecule inhibitors such as Umifenovir (Arbidol) have been shown to interact with HA to inhibit the fusion process or attachment (PubMed: 30639124). Developing broad-spectrum inhibitors for the RBS remains a challenge due to the structural diversity across different influenza subtypes like H1N1 and H3N2.

Other names

Hemagglutinin globular headHA1 receptor-binding domainSialic acid binding siteHA RBS

Inhibition of viral attachment to host cell sialic acid receptors, thereby preventing viral entry and subsequent replication cycles.