Influenza A virus H5 hemagglutinin (H5 HA) (H5 HA)

Influenza A virus H5 hemagglutinin (H5 HA) is the primary surface glycoprotein of H5-subtype influenza viruses, including the highly pathogenic H5N1 avian flu [PubMed: 29165205]. It functions as a class I fusion protein, responsible for recognizing and binding to sialic acid receptors on host cells and subsequently mediating the fusion of the viral envelope with the host endosomal membrane [UniProt: Q6DQV1]. Because of its prominent position on the viral envelope, H5 hemagglutinin is the principal target for neutralizing antibodies elicited by infection or vaccination [PubMed: 25124742]. Vaccines targeting H5 HA aim to produce antibodies that bind to the immunodominant globular head or the more conserved stem region to prevent viral entry [PubMed: 30104374]. The high rate of mutation in the HA gene allows the virus to undergo antigenic drift, which can reduce the effectiveness of vaccine-elicited antibodies over time. Consequently, H5 HA is a major focus for pandemic preparedness and the development of universal influenza vaccines [WHO].

Other names

Hemagglutinin H5H5N1 hemagglutininHA5Influenza A virus hemagglutinin H5 subtypeInfluenza A virus H5 hemagglutinin – vaccine-elicited antibody

Vaccine-elicited antibodies bind to the H5 hemagglutinin protein to neutralize the virus by blocking its attachment to host cell sialic acid receptors or by inhibiting the conformational changes required for membrane fusion [PubMed: 30104374].