Hemagglutinin globular head domain (HA globular head domain)

The hemagglutinin globular head domain is the membrane-distal, antigenic region of the influenza hemagglutinin (HA) glycoprotein, composed mainly of HA1 subunit residues. It contains the receptor-binding site (RBS) that recognizes sialic acid residues on host cells, enabling viral attachment and entry. The globular head domain is the primary target for neutralizing antibodies, making it a central focus for influenza vaccine development and immunological studies. High variability in this region (antigenic drift) underlies the necessity for frequent influenza vaccine updates. Structural features include a compact arrangement of α-helices and β-sheets forming a globular domain, with surface loops (130-loop, 150-loop, 190-helix, 220-loop) surrounding the conserved receptor-binding pocket. This domain is a well-validated therapeutic and vaccine target critical to influenza virus infectivity, immunity, and vaccine efficacy.

Other names

HA globular headInfluenza hemagglutinin head domainHA1 globular domainHemagglutinin HA1 head

Antibodies bind the globular head domain and block virus receptor engagement, preventing viral attachment and entry into host cells. Vaccines elicit antibodies that target the head, neutralizing the virus.