The Spanish flu pandemic of 1918 killed more people than died in the First World War—at least 20 million—but why this strain of the disease was so virulent has remained a mystery. Analysis of the crystal structure of viral hemagglutinin (HA)—a major surface antigen that mediates binding to the host cell—shows the 1918 virus antigen is related to the avian antigen, suggesting that the virulence resulted from a recent chicken/human cross-species jump.
Alan Hay, director of the World Health Organization Collaborating Centre for Reference and Research on Influenza at the National Institute for Medical Research (NIMR) and who was not involved in the studies, told The Scientist, “All this information helps us to understand what sort of changes may facilitate human infection by an avian virus. The accumulated data that we have on the structural detail helps us to look for changes which might have an impact on the ability ...
