Trimming Sugars Yields Better Flu Antibodies

Truncating the sugar chains attached to an influenza protein leads to antibodies that can better bind to and neutralize the virus, reports a group led by Che Ma and Chi-Huey Wong at Academia Sinica, in Taiwan (Proc. Nat. Acad. Sci. USA, DOI: 10.1073/pnas.0909696106). The team investigated the glycosylation of influenza hemagglutinin (HA), a glycoprotein on the viral coat that enables the virus to enter respiratory-tract cells by binding to glycan receptors. The team compared normally glycosylated HA with HA that was enzymatically pared down in three ways: to remove just the sialic acid groups from the sugar chains, to leave a high proportion of mannose groups, and to truncate the sugar chains so that just a single N-acetylglucosamine remained at each glycosylation site. The researchers found that antibodies raised against the N-acetylglucosamine-only protein showed better binding affinity and neutralization activity against the influenza virus than antibodies raised against fully glycosylated HA. The results may point toward a new strategy for making vaccines against influenza and other viruses, the authors say.