Influenza virus hemagglutinin stalk domain (HA stalk)

The influenza virus hemagglutinin stalk domain is the highly conserved structural region at the base of hemagglutinin (HA), the major surface glycoprotein of influenza viruses. HA is synthesized as a precursor (HA0) and cleaved into HA1 (globular head) and HA2 (stalk), with the stalk composed of most or all of HA2 and portions of HA1. The stalk domain supports the head, mediates pH-triggered conformational changes that drive membrane fusion for viral entry, and contains conserved epitopes targeted by broadly neutralizing antibodies. Unlike the variable globular head, the stalk domain is relatively conserved across influenza subtypes, making it a promising target for universal vaccine and antibody therapies. Broadly neutralizing antibodies can bind the stalk, locking HA in its pre-fusion state and preventing infection. The stalk domain is critical for both viral infectivity and as a focus for next-generation anti-influenza interventions.

Other names

Hemagglutinin stemHA stemStalk domain of hemagglutininInfluenza hemagglutinin stalk

Neutralizing antibodies: Bind to conserved stalk epitope, inhibit conformational changes necessary for membrane fusion, block viral entry Small-molecule inhibitors: Stabilize pre-fusion conformation, block membrane fusion process