ABSTRACT
The SoxRS regulon is induced when bacterial cells are exposed to redox-cycling agents such as menadione or paraquat. In this paper it is shown that a physical agent, such as ultraviolet radiation with a wavelength of 312 nm (UVB) can induce soxS gene expression. The results indicate that this induction involves the RpoS protein. Moreover, an unexpected increase of soxS gene expression independent of a functional soxR gene in UVB-irradiated cells has been verified. This increase could be explained by transcription of soxS gene in a rpoS-dependent pathway.
Subject(s)
Bacterial Proteins/metabolism , Escherichia coli Proteins/metabolism , Escherichia coli/physiology , Escherichia coli/radiation effects , Gene Expression Regulation, Bacterial/radiation effects , Oxidative Stress/radiation effects , Sigma Factor/metabolism , Trans-Activators/metabolism , Ultraviolet Rays , Cell Survival/radiation effects , Dose-Response Relationship, Radiation , Escherichia coli/cytology , Escherichia coli Proteins/genetics , Oxidative Stress/physiology , Radiation Dosage , Trans-Activators/geneticsABSTRACT
Systemic and mucosal antibody responses against both the major subunit of colonization factor antigen I (CFA/I) of enterotoxigenic Escherichia coli (ETEC) and the somatic lipopolysaccharide expressed by recombinant bivalent Salmonella vaccine strains were significantly enhanced by coadministration of a detoxified derivative with preserved adjuvant effects of the ETEC heat-labile toxin, LT((R192G)). The results further support the adjuvant effects of LT((R192G)) and represent a simple alternative to improve responses against passenger antigens expressed by orally delivered Salmonella vaccine strains.
Subject(s)
Adjuvants, Immunologic/pharmacology , Antibodies, Bacterial/biosynthesis , Bacterial Toxins/pharmacology , Enterotoxins/pharmacology , Escherichia coli Proteins , Escherichia coli/immunology , Fimbriae Proteins , Immunity, Mucosal , Animals , Antigens, Bacterial/administration & dosage , Antigens, Bacterial/genetics , Bacterial Proteins/administration & dosage , Bacterial Proteins/genetics , Bacterial Toxins/genetics , Bacterial Vaccines/administration & dosage , Bacterial Vaccines/genetics , Enterotoxins/genetics , Escherichia coli/genetics , Lipopolysaccharides/administration & dosage , Mice , Mice, Inbred BALB C , Mutation , Salmonella typhimurium/genetics , Salmonella typhimurium/immunology , Vaccines, Synthetic/administration & dosage , Vaccines, Synthetic/geneticsABSTRACT
The induction of systemic (IgG) and mucosal (IgA) antibody responses against the colonization factor I antigen (CFA/I) of enterotoxigenic Escherichia coli (ETEC) was evaluated in mice primed with an intramuscularly delivered CFA/I-encoding DNA vaccine followed by two oral immunizations with a live recombinant Salmonella typhimurium vaccine strain expressing the ETEC antigen. The booster effect induced by the oral immunization was detected two weeks and one year after the administration of the DNA vaccine. The DNA-primed/Salmonella-boosted vaccination regime showed a synergistic effect on the induced CFA/I-specific systemic and secreted antibody levels which could not be attained by either immunization strategy alone. These results suggest that the combined use of DNA vaccines and recombinant Salmonella vaccine strains can be a useful immunization strategy against enteric pathogens.
Subject(s)
Bacterial Proteins/immunology , Bacterial Vaccines , Enterotoxins , Escherichia coli Infections/prevention & control , Escherichia coli/immunology , Fimbriae Proteins , Fimbriae, Bacterial/immunology , Salmonella typhimurium/immunology , Vaccines, DNA , Animals , Antibody Formation , Escherichia coli Infections/immunology , Immunity, Mucosal , Immunization, Secondary , Mice , Mice, Inbred BALB CABSTRACT
The induction of systemic (IgG) and mucosal (IgA) antibody responses against the colonization factor I antigen (CFA/I) of enterotoxigenic Escherichia coli (ETEC) was evaluated in mice primed with an intramuscularly delivered CFA/I-encoding DNA vaccine followed by two oral immunizations with a live recombinant Salmonella typhimurium vaccine strain expressing the ETEC antigen. The booster effect induced by the oral immunization was detected two weeks and one year after the administration of the DNA vaccine. The DNA-primed/Salmonella-boosted vaccination regime showed a synergistic effect on the induced CFA/I-specific systemic and secreted antibody levels which could not be attained by either immunization strategy alone. These results suggest that the combined use of DNA vaccines and recombinant Salmonella vaccine strains can be a useful immunization strategy against enteric pathogens
Subject(s)
Animals , Mice , Adhesins, Escherichia coli , Bacterial Proteins/immunology , Bacterial Vaccines , Enterotoxins , Escherichia coli/immunology , Immunization, Secondary , Salmonella typhimurium/immunology , Vaccines, DNA , Antibody Formation , Immunity, Mucosal , Mice, Inbred BALB C , Salmonella Infections/immunologyABSTRACT
An expression plasmid (pCFA-1) carrying the cfaB gene that codes for the enterotoxigenic Escherichia coli (ETEC) fimbrial adhesin colonization factor antigen I (CFA/I) subunit was constructed and used to transform a derivative of the attenuated Salmonella typhimurium aroA vaccine strain SL3261 carrying an F'lacIq. Treatment of the transformed strain with isopropyl-beta-D-thiogalactopyranoside (IPTG) resulted in elevated in vitro expression of the CFA/I subunit. Although flagellar function and lipopolysaccharide (LPS) synthesis were similar in both the parental and the recombinant strains, spleen colonization was reduced in the recombinant strain. All BALB/c mice parenterally inoculated with the recombinant strain developed significant anti-CFA/I and anti-LPS serum antibody titers (P < 0.05). Moreover, 2 of 5 mice orally inoculated with the engineered Salmonella strain developed anti-CFA/I intestinal IgA (P > 0.05) while 4/5 of the same mice developed anti-LPS IgA (P < 0.05). The results indicate that the vaccine strain elicited an antibody response against the bacterial host both after oral and intravenous immunization while the response against the CFA/I antigen was significant only after inoculation by the intravenous route.
Subject(s)
Antigens, Bacterial/immunology , Bacterial Proteins/immunology , Bacterial Vaccines/immunology , Diarrhea/prevention & control , Escherichia coli Infections/prevention & control , Fimbriae Proteins , Salmonella typhimurium/immunology , Animals , Antibody Formation/immunology , Diarrhea/immunology , Diarrhea/microbiology , Escherichia coli Vaccines , Mice , Mice, Inbred BALB C , Vaccines, Attenuated , Vaccines, SyntheticABSTRACT
An expression plasmid (pCFA-1) carrying the cfaB gene that codes for the enterotoxigenic Escherichia coli (ETEC) fimbrial adhesin colonization factor antigen I(CFA/I) subunit was constructed and used to transform a derivative of the attenuated Salmonella typhimurium aroA vaccine strain SL3261 carrying an F'lacl(q). Treatment of the transformed strain with isopropyl-beta-D-thiogalactopyranoside (IPTG) resulted in elevated in vitro expression of the CFA/I subunit. Although flagellar function and lipopolysaccharide (LPS) synthesis were similar in both the parental and the recombinant strains, spleen colonization was reduced in the recombinant strain. AII BALB/c mice parenteally inoculated with the recombinant strain developed significant anti-CFA/I and anti-LPS serum antibody titers (P<0.05). Moreover, 2 of 5 mice orally inoculated with the engineered Salmonella strain developed anti-CFA/I intestinal IgA (P>0.05) while 4/5 of the same mice developed anti-LPS (P<0.05). The results indicate that the vaccine strain elicited an antibody response against the bacterial host both after oral and intravenous immunization while the response against the CFA/I antigen was significant only after inoculation by the intravenous route.
Subject(s)
Animals , Mice , Antigens, Bacterial/immunology , Bacterial Vaccines/immunology , Diarrhea , Escherichia coli Infections , Salmonella typhimurium/immunology , Antibody Formation/immunology , Bacterial Proteins , Diarrhea/immunology , Diarrhea/microbiology , Enterotoxins/biosynthesis , Mice, Inbred BALB C , Molecular Sequence Data , Plasmids/immunology , Vaccines, Attenuated , Vaccines, SyntheticABSTRACT
Mutagenesis induced by several genotoxic agents has been reported to be inhibited by cobaltous chloride. In order to study the effects of this metal in some SOS functions we evaluated mutagenesis, lysogenic induction and phage reactivation in Escherichia coli cells treated with CoCl2. We detected that cobaltous chloride, when present in the plating medium, was able to block mutagenesis and lysogenic induction promoted by UV irradiation. We also found that CoCl2 blocked protein synthesis, so we propose that this effect can be responsible for the antimutagenic and antilysogenic effects of this metal. On the other hand, if the cells were treated for a short period of time with CoCl2, in the absence of Mg, we observed that cobaltous chloride per se was able to promote lysogenic induction as well as to enhance the phage reactivation induced by UV irradiation. We conclude that depending on experimental conditions, cobaltous chloride may act either as an inhibitor or as an inducer of the SOS functions.
