Enlarge Image Crystal ball. The 2009 pandemic virus has the same amino acids at the tip of its HA as the 1918 strain shown here bound to an antibody (red and yellow ribbons) taken from a survivor of the 1918 pandemic. Credit: R. Xu et al., Science (Advanced Online Edition) Researchers have found that the H1N1 swine influenza virus that last year caused the first human pandemic in 4 decades shares an important surface protein with the virus responsible for the 1918 flu, the deadliest in human history. This newfound similarity answers many mysteries about the 2009 pandemic, including...