Influenza A virus H1N1 hemagglutinin globular head (HA1-GH) (HA1-GH)

The globular head of the Influenza A H1N1 hemagglutinin (HA) is the membrane-distal domain of the HA1 subunit, primarily responsible for viral attachment to host cells [1, 8]. It contains the receptor binding site (RBS), which recognizes and binds to terminal sialic acid residues on host cell surface glycoproteins, initiating viral entry via endocytosis [1, 22]. This domain is also the primary target for neutralizing antibodies elicited by seasonal vaccines and natural infection, making it a critical component of the host immune response [11, 13]. However, the globular head is characterized by high genetic plasticity and frequent mutations, a process known as antigenic drift, which allows the virus to evade pre-existing immunity [1, 12, 13]. Therapeutic strategies targeting this domain include monoclonal antibodies that block the RBS and small molecule or peptide inhibitors designed to mimic sialic acid or interfere with the binding pocket [3, 16, 22]. Because of its role in host specificity and immune evasion, the globular head remains a focal point for the development of next-generation vaccines and entry inhibitors [7, 21].

Other names

Hemagglutinin HA1 subunit [4, 7]Hemagglutinin globular head domain [1, 15]Receptor binding domain of hemagglutinin (HA1-RBD) [1, 18]H1N1 HA1 [9, 12]

Inhibition of viral attachment by blocking the receptor binding site (RBS) on the globular head, preventing interaction with host cell sialic acid receptors [1, 3, 22].