How to become a pathogen

Abstract

For most bacterial species, virulence is viewed as a derived state, whereby pathogens acquire certain loci and are rendered virulent. The majority of virulence genes in Salmonella are present in closely related nonpathogenic species, and most genes known to be confined to the salmonellae are not essential for virulence. Alternative evolutionary scenarios may explain the origins of pathogenicity in Salmonella.