Induction of Salmonella stress proteins upon infection of macrophages.

Regulated expression of bacterial genes allows a pathogen to adapt to new environmental conditions within the host. The synthesis of over 30 Salmonella proteins is selectively induced during infection of macrophages. Two proteins induced by Salmonella are the heat shock proteins GroEL and DnaK. Two avirulent, macrophage-sensitive mutants of Salmonella synthesize GroEL and DnaK but fail to synthesize different subsets of proteins normally induced within the macrophage. Enhanced expression of selected Salmonella proteins contributes to bacterial survival within macrophages and may also contribute to the apparent immunodominance of heat shock proteins.