Influenza,AIDS,andEbola:Virusesarenormallydefinedaspathogens.Mostvirusesare,however,notenemiesorkillers.Well-knownvirologistandcancerresearcherKarinMoellingdescribessurprisinginsightsaboutacompletelynewandunexpectedworldofviruses.Virusesareubiquitous,intheoc