Influenza A virus hemagglutinin H7N9 (HA (H7N9))

Influenza A virus hemagglutinin H7N9 is a surface glycoprotein (antigen) of the H7N9 subtype of influenza A virus, responsible for mediating viral attachment and entry into host cells. The hemagglutinin binds to host cell membrane sialic acid residues, with specificity determined by recognition of α2-3-linked (avian) and α2-6-linked (human) sialosides. Key mutations, such as G186V and Q226L, alter the HA’s receptor-binding preferences, modulating the potential for zoonotic transmission and adaptation to human hosts. HA is the primary antigenic determinant for immune recognition and is the focus of vaccine and antibody-based prophylaxis. H7N9 HA has been associated with several zoonotic outbreaks since 2013, leading to human infections with a risk of severe respiratory illness and pandemic threat due to its capacity for mutation and recombination. The protein remains a critical target for both surveillance and intervention strategies in influenza public health.

Other names

H7N9 HA proteinH7 hemagglutininHemagglutinin subtype H7 (from Influenza A virus H7N9)Influenza hemagglutinin H7N9

Receptor blockers: Antibodies or small molecules block HA’s ability to bind to host sialic acid receptors, preventing viral entry. Inhibitors of viral fusion: Prevent conformational changes required for viral membrane fusion. Neutralization by antibodies: Vaccine-induced or therapeutic antibodies recognize and neutralize HA.