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Abstract
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.
Highlights
EnterotoxigenicEscherichia coli (ETEC) causes diarrheal disease with high morbidity and mortality rates among children in developing countries [1]
In the present study we report an alternative strategy of intracellular colonization factor antigen I (CFA/I) subunit expression based on the use of an attenuated S. typhimurium strain carrying a double-plasmid regulatory system
Since there was no significant difference in the expression of the colonization factor antigens (CFAs)/I subunit in cells induced by IPTG concentrations ranging from 0.1 mM to 1 mM, the concentration of 0.5 mM was chosen for further experiments (Figure 1A)
Summary
EnterotoxigenicEscherichia coli (ETEC) causes diarrheal disease with high morbidity and mortality rates among children in developing countries [1]. It is the infectious agent associated with traveller’s diarrhea, which afflicts people travelling to places where the pathogen is endemic [1,2]. ETEC relies on its ability to colonize the small intestine to cause disease. ETEC adhesion is usually mediated by fimbriae, known as colonization factor antigens (CFAs), which bind to glycolipid receptors on the enterocyte surface. The CFA/I is one of the best characterized ETEC fimbriae and has a widespread occurrence in endemic areas, including South America [4,5,6]. The CFA/I fimbriae contain a single protein subunit encoded by the plasmidial cfaB gene endowed with structural and functional (adhesion) roles [7]
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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