Influenza A Virus Hemagglutinin Glycoproteins
David A. Steinhauer
from: Influenza: Molecular Virology (Edited by: Qinghua Wang and Yizhi Jane Tao). Caister Academic Press, U.K. (2010)
The influenza A virus hemagglutinin glycoprotein (HA) is the principle mediator of viral entry into host cells. It is responsible for attachment of virions to sialic acid-containing receptors on the host cell surface, and for inducing membrane fusion between viral envelopes and cellular endosomal membranes following endocytosis. HA serves a classic example of a type I membrane glycoprotein, with a cleaved N-terminal signal sequence, a membrane anchor domain near the C-terminus, and post-translational modifications resulting from the addition of N-linked oligosaccharide side chains to the ectodomain, and acylation of cysteine residues in the cytoplasmic tail region. HA spikes on the viral surface are also the major target for neutralizing antibodies, and as such, the antigenic properties of the HA are of fundamental significance for the design of influenza vaccines. The depth of knowledge relating to high resolution atomic structures of HA in various forms have made it a prototype for the investigation of viral glycoproteins in general, and this chapter outlines some of the special features that have derived from structure-function studies on HA read more ...