Influenza hemagglutinin receptor-binding site (HA-RBS) (HA-RBS)

The Influenza hemagglutinin receptor-binding site (HA-RBS) is a critical functional domain located at the apex of the hemagglutinin protein on the surface of the influenza virus. Its primary biological role is to facilitate viral entry by binding to specific sialic acid receptors on the host cell membrane, a process that determines host range and tissue tropism (Skehel & Wiley, 2000). For instance, human influenza viruses typically prefer α2,6-linked sialic acids found in the upper respiratory tract, whereas avian viruses prefer α2,3-linked sialic acids (UniProt P03437). As the initial point of contact between the virus and the host, the RBS is a major target for neutralizing antibodies elicited by natural infection or vaccination (Whittle et al., 2011). However, the site is under intense selective pressure, leading to frequent mutations known as antigenic drift, which allow the virus to escape immune detection (Ekiert et al., 2012). Therapeutic interventions targeting the RBS include monoclonal antibodies like CH65 and C05, as well as experimental small-molecule mimics designed to block viral attachment. Successfully targeting this site is challenging due to the high variability of the surrounding residues, necessitating the development of agents that can recognize conserved features within the binding pocket.

Other names

HA1 receptor-binding domainSialic acid-binding siteHemagglutinin binding pocketHA-RBD

Competitive inhibition of viral attachment to host cell sialic acid receptors, thereby preventing viral entry and subsequent infection.