RESUMO
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.
Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/fisiologia , Escherichia coli/efeitos da radiação , Regulação Bacteriana da Expressão Gênica/efeitos da radiação , Estresse Oxidativo/efeitos da radiação , Fator sigma/metabolismo , Transativadores/metabolismo , Raios Ultravioleta , Sobrevivência Celular/efeitos da radiação , Relação Dose-Resposta à Radiação , Escherichia coli/citologia , Proteínas de Escherichia coli/genética , Estresse Oxidativo/fisiologia , Doses de Radiação , Transativadores/genéticaRESUMO
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
Assuntos
Animais , Camundongos , Adesinas de Escherichia coli , Proteínas de Bactérias/imunologia , Vacinas Bacterianas , Enterotoxinas , Escherichia coli/imunologia , Imunização Secundária , Salmonella typhimurium/imunologia , Vacinas de DNA , Formação de Anticorpos , Imunidade nas Mucosas , Camundongos Endogâmicos BALB C , Infecções por Salmonella/imunologiaRESUMO
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.