Influenza A virus H7 hemagglutinin (H7HA) (H7HA)

Influenza A virus H7 hemagglutinin (H7HA) is a major surface glycoprotein and a critical virulence factor of the H7 subtype of Influenza A viruses, including the highly pathogenic H7N9 strain [1, 10]. As a class I fusion protein, it exists as a homotrimer on the viral envelope, where it mediates the initial stages of infection [4, 16]. The HA1 subunit is responsible for recognizing and binding to sialic acid-containing receptors on the host cell surface, while the HA2 subunit facilitates the fusion of the viral and endosomal membranes following a low-pH-induced conformational change [4, 14]. This dual functionality makes H7HA essential for viral entry and a primary determinant of host range and pathogenicity [13, 17]. In the context of therapeutics, H7HA is the principal target for both seasonal and pandemic vaccines, as well as for the development of neutralizing monoclonal antibodies [5, 15]. Drugs and antibodies targeting H7HA typically work by either blocking the receptor-binding site on the globular head to prevent attachment or by binding to the conserved stem region to inhibit the structural rearrangements necessary for membrane fusion [7, 9]. Notable therapeutic candidates include broadly neutralizing antibodies like MEDI8852 and small molecule fusion inhibitors like tert-butyl hydroquinone (TBHQ) [10, 11]. However, the high rate of antigenic drift in the HA protein presents a significant challenge, necessitating continuous monitoring and the development of universal influenza therapies [6, 15].

Other names

H7 hemagglutininHemagglutinin subtype H7H7N9 hemagglutininHA7Influenza A virus H7N9 hemagglutinin

Drugs targeting H7 hemagglutinin primarily act by neutralizing the virus through two main mechanisms: blocking the receptor-binding site on the HA1 head domain to prevent attachment to host sialic acid receptors [4, 8], or binding to the conserved HA2 stem region to inhibit the pH-dependent conformational change required for membrane fusion and viral entry [7, 10].