Return and reformation after a century-from 1918 to 2009 H1N1

Undoubtedly,H1N1 has been a keyword for the past year of 2009.This swine influenza virus is the first pandemic of the 21st century(announced by the World Health Organization(WHO)on June 11th,2009)and took around 18,000 lives by April,2010(http://www.who.int/csr/don/2010_04_23a/en/index.html).Despite of the well-acknowledged high mutation rate for pandemic influenza viruses,the Wilson group at the Scripps Research Institute(Xu et al.,2010),the Stevens group at Centers for Disease Control and Prevention(Yang et al.2010),and the Gao group at the Institute of Microbiology,Chinese Academy of Sciences(in the current issue of Protein&Cell)independently discovered that the 1918 and 2009 pandemic influenza viruses share fantastic similarities in regards to the structure of hemagglutinin(HA),which is the major influenza virus surface envelope protein.In addition,the Gao group also reported the changes of N-glycosylation sites in the HA protein and proposed another underlying evolutionary hint.