Antigenic drift allows influenza virus to escape seasonal vaccination and necessitates the yearly development of new vaccines. However, two related papers in Science by Goudsmit et al. and Lanzavecchia et al., as well as one by Harrison et al. in the Proceedings of the National Academy of Science, suggest the possibility of generating broadly neutralizing but distinct antibodies to influenza virus. Hemagglutinin, the main surface antigen on influenza virus, binds its cellular receptor sialic acid and thereby gains entry to the cell. In the Science papers, the authors identify antibodies to the relatively conserved stem region of hemagglutinin. Depending on the antibody, these could effectively neutralize influenza virus in vitro and in vivo throughout the major influenza subgroup 2 or, to a certain extent, subgroups 1 and 2. In contrast, the antibody identified by Harrison and colleagues demonstrates broad reactivity to influenza H1N1 strains of subgroup 1 by binding to the globular head of hemagglutinin in a way that closely mimics that of the natural receptor sialic acid.

Science 333, 843–850 & 850–856 (2011); Proc. Natl. Acad. Sci. USA 108, 14216–14221 (2011)