Hemagglutinin protein from Influenza A virus subtype H7N9 (HA (H7N9))

The hemagglutinin (HA) protein from Influenza A virus subtype H7N9 is a trimeric viral envelope glycoprotein responsible for binding sialic acid-containing receptors on host cells, thereby facilitating viral entry and infection[2][3][7]. It consists of a globular head with a receptor binding site (RBS) and a stalk region required for membrane fusion[3][1]. H7N9 HA shows variable specificity for avian (α2-3-linked sialic acid) and human (α2-6-linked) receptors, with mutations (such as Gln226Leu) increasing human receptor binding and pandemic potential[2][4][7]. As the principal antigenic determinant, HA is the main target of neutralizing antibodies elicited by infection or vaccination, and structural studies are key for vaccine design and pandemic surveillance[8][9]. HA from H7N9 is considered a high-priority therapeutic and vaccine target due to its essential role in viral pathogenesis, transmission, and immune recognition[4][6].

Other names

Hemagglutinin (H7N9)H7N9 HAInfluenza A virus H7N9 hemagglutininH7 hemagglutinin (when subtype is specified)

Blockade of receptor binding (prevents viral entry by inhibiting HA interaction with host sialic acid receptors) Inhibition of membrane fusion (prevents the conformational changes required for fusion between viral and host membranes) Neutralization of virus particle by direct antibody binding