Pbs: Nova Science Now: Genetically Engineering the Avian Flu

This video examines the threat of a virus being spread from birds to humans, and then from humans to humans. It details the mechanisms viruses use to infect cells, and explores how mutations in a virus may change its virulence and how it can spread. It also looks at work being done with a re-created flu virus -- from the deadly 1918 strain -- that may help prevent future flu pandemics. [5:08]