title: Induction of the phoE promoter upon invasion of Salmonella typhimurium into eukaryotic cells.
abstract: Live attenuated Salmonella typhimurium strains expressing foreign antigens can be used for vaccination purposes. Due to deleterious effects of constitutive, high-level expression of the heterologous antigens, there is often strong selection pressure against plasmids encoding these antigens, resulting in rapid segregation in vivo. In vivo-inducible promoters may be a good alternative for constitutive promoters. The outer membrane protein PhoE of Escherichia coli is being used as a carrier for foreign antigenic determinants. Here we studied whether its expression from a plasmid is induced in S. typhimurium upon invasion of eukaryotic cells. This appeared to be the case. Furthermore, a S. typhimurium phoE mutant was constructed and the effects of the mutation on invasion, intracellular survival and virulence were studied. Survival in HEp-2 cells or in the macrophage-like cell line J744 was not, or only slightly, affected. Furthermore, the mutant appeared to be as virulent for mice as the wild-type strain.
authors.affiliation: Department of Molecular Cell Biology, Utrecht University, Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Janssen
authors.forename: G M
authors.initials: GM
authors.lastname: Verjans
authors.forename: J G
authors.initials: JG
authors.lastname: Kusters
authors.forename: J
authors.initials: J
authors.lastname: Tommassen
mesh_terms: D002460:Cell Line; D029968:Escherichia coli Proteins; D005057:Eukaryotic Cells / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D010641:Phenotype; D018272:Porins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012486:Salmonella typhimurium / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D018272:Porins; C082922:PhoE protein, E coli