Hemagglutinin (H7) (HA)

H7 hemagglutinin (HA) is the primary surface glycoprotein of the H7N9 avian influenza virus, playing a dual role in viral attachment and membrane fusion [1.3.1, 1.5.2]. It mediates entry into host cells by binding to sialic acid receptors—specifically favoring avian-type alpha-2,3 linkages, though mutations can increase affinity for human-type alpha-2,6 linkages [1.1.1, 1.3.3]. As the principal target for the host's neutralizing antibody response, HA is the central component of H7N9 vaccines and a focus for developing novel antiviral therapies [1.2.4, 1.4.1]. Drugs targeting HA aim to block the initial stages of the viral life cycle, either by preventing receptor binding or by inhibiting the pH-dependent conformational change required for fusion with the endosomal membrane [1.2.2, 1.5.1]. Despite its therapeutic potential, H7 HA is known for its relatively low immunogenicity and high rate of antigenic drift, which necessitates the use of potent adjuvants and continuous monitoring of emerging viral lineages [1.3.4, 1.4.1].

Other names

H7 HAHemagglutinin H7H7N9 HemagglutininH7 glycoproteinInfluenza A virus H7N9 hemagglutinin

Hemagglutinin inhibitors prevent viral entry by blocking the binding of the virus to host sialic acid receptors or by inhibiting the pH-dependent conformational change required for membrane fusion [1.2.2, 1.5.4]. Some agents, such as Nitazoxanide, interfere with the post-translational maturation and transport of the hemagglutinin protein to the host cell surface, preventing the assembly of mature virions [1.2.1].