Induction of the phoE promoter upon invasion of Salmonella typhimurium into eukaryotic cells.
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.
Janssen
R
R
Department of Molecular Cell Biology, Utrecht University, Netherlands.
Verjans
G M
GM
Kusters
J G
JG
Tommassen
J
J
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
D029968:Escherichia coli Proteins; D018272:Porins; C082922:PhoE protein, E coli