Hemagglutinin protein H5 (Influenza A virus) (H5)

The Hemagglutinin protein H5, often abbreviated as H5, is a critical surface glycoprotein of the Influenza A virus, specifically the H5 subtype associated with avian influenza. It functions as a class I fusion protein, playing a dual role in viral infectivity by binding to sialic acid receptors on host cells and mediating the fusion of the viral envelope with the host cell membrane, thereby facilitating viral entry. H5 is a major determinant of the virus's host range and virulence, contributing significantly to the pathogenicity of highly pathogenic avian influenza (HPAI) H5N1 strains. Infection with H5N1 can lead to severe respiratory disease, including viral pneumonia, and is associated with high mortality rates in both poultry and humans. As a therapeutic target, H5 is central to vaccine development, with various H5N1 vaccines designed to induce antibodies that block its functions and neutralize viral infectivity. Additionally, monoclonal antibodies and specific inhibitors are being explored to target H5 directly, preventing viral attachment and entry. However, challenges remain due to the virus's antigenic drift and the potential for drug resistance.

Other names

Hemagglutinin H5HA H5H5 proteinH5 hemagglutininAvian influenza H5

Vaccines targeting H5 induce antibodies that block its functions, such as receptor binding and membrane fusion, thereby neutralizing virus infectivity. Monoclonal antibodies directly bind to H5, preventing viral attachment and entry into host cells. Other inhibitors, like curcumin derivatives and AL-1, interfere with H5 to block virus binding to cellular receptors, while DAS181 cleaves sialic acid receptors on host cells, preventing H5 from binding.