Influenza viral hemagglutinin (HA) (HA)

Influenza viral hemagglutinin (HA) is a homotrimeric surface glycoprotein essential for the infectivity of the influenza virus (UniProt P03437). It functions by binding to sialic acid receptors on the host cell surface, which triggers receptor-mediated endocytosis (NCBI, PMC4676286). Within the acidic environment of the endosome, HA undergoes a significant conformational change that facilitates the fusion of the viral and endosomal membranes, releasing the viral ribonucleoproteins into the host cytoplasm (PubMed, 29439177). HA is the primary antigen targeted by the immune system and is the principal component of most influenza vaccines (CDC). Due to its high rate of mutation, known as antigenic drift, HA is a major focus for the development of universal vaccines and novel antiviral drugs like Umifenovir, which acts as a fusion inhibitor (DrugBank DB13609). Therapeutic antibodies targeting the conserved stem region of HA are currently being explored to provide broader protection against diverse influenza strains (PubMed, 30108804).

Other names

HemagglutininHAInfluenza HAH1H2H3

Inhibition of viral attachment to host cell sialic acid receptors and prevention of pH-dependent membrane fusion within the endosome (PubMed, 30108804).