Influenza A virus hemagglutinin (H5 subtype, clade 2.3.4.4b, B1 lineage) (H5 HA (B1 lineage))

Influenza A virus hemagglutinin (HA) is the primary surface glycoprotein responsible for viral entry into host cells. The H5 subtype, particularly within clade 2.3.4.4b, has gained significant global attention due to its high pathogenicity in avian species and its recent spillover into various mammals, including cattle and humans. The B1 lineage is a specific phylogenetic sublineage of the H5 HA gene that emerged and began co-circulating with the B2 lineage around 2021, primarily in Europe and North America. HA functions by binding to sialic acid receptors on the host cell surface and subsequently mediating the fusion of the viral envelope with the endosomal membrane under acidic conditions. As the major antigen of the virus, it is the primary target for seasonal and pandemic vaccines, as well as for the development of broadly neutralizing antibodies. Therapeutic strategies targeting this molecule aim to block viral attachment or fusion, thereby preventing infection and reducing disease severity.

Other names

H5 hemagglutininH5 HAClade 2.3.4.4b B1 lineage HAHPAI H5N1 B1 lineage hemagglutininInfluenza A virus H5N1 hemagglutinin

Inhibition of viral attachment to host sialic acid receptors, inhibition of pH-dependent membrane fusion, and neutralization of viral infectivity through antibody binding to the HA head or stem domains.