Wilson's laboratory used X-ray crystallography to determine the atomic structures of the H7N9 hemagglutinin protein bound to these sialic acid receptor molecules. (sciencedaily.com)
The simplified cartoon below represents five hemagglutinin protein sequences mixed together into one. (sciencenews.org)
The method described by Kawaoka and his colleagues is conceptually different in that it mimics the mutations that occur in nature and accelerates their accumulation in the critical hemagglutinin protein. (sciencedaily.com)