Substitutions affecting the HA–NA–receptor balance preceded the emergence of the pandemic 2009 H1N1 virus
Significance Influenza A pandemics greatly affect the human population every few decades when a novel animal virus breaches the species barrier. The H1N1 pandemic of 2009 (H1N1pdm09) is the first pandemic in the genomics era, which allows us to identify and study in detail mutations in prepandemic swine viruses associa...