Promoter activities in Vibrio cholerae ctx phi prophage

Abstract

Comparison of cholera toxin (CT) production directed by different gene constructs and S1 nuclease mapping revealed the presence of a ctxB-specific promoter within the ctxA coding sequence. Initiation of transcription in this region occurred in wild-type El Tor and classical biotype choleragenic vibrios. We propose that transcription from the ctxB-specific promoter and a stronger ribosomal binding site on the ctxB mRNA synergistically contribute to achieve the correct (5B:1A) subunit stoichiometry. Plasmid pB, a CT promoterless vector expressing only CTB, was used to detect promoter activity by restoration of A-subunit synthesis. Promoter activity expressed in vitro and in vivo was detected upstream of the zonula occludens toxin gene, suggesting that this factor could be produced in vivo to contribute to fluid accumulation. No promoter activity was detected in vitro and in vivo upstream from the accessory cholera enterotoxin gene.

Preliminary Assessment of the Safety and Immunogenicity of a New CTXΦ-Negative, Hemagglutinin/Protease-Defective El Tor Strain as a Cholera Vaccine Candidate

“…Measurement of CT. CT was measured in culture supernatants by GM 1 enzyme-linked immunosorbent assay (ELISA) by using monoclonal antibody 1G10G5 against CTA and peroxidase-conjugated anti-mouse immunoglobulin G (IgG) as the primary and secondary antibodies, respectively (7).…”

Zonula Occludens Toxin Is a Powerful Mucosal Adjuvant for Intranasally Delivered Antigens

“…Zonula occludens toxin (Zot) is a single polypeptide chain of 44.8 kDa encoded by the filamentous bacteriophage CTX⌽, present in toxigenic strains of V. cholerae (1,7,30). Zot has the ability to increase the permeability of the small intestine by affecting the structure of epithelial tight junctions (8,9), thus allowing the passage of macromolecules by the paracellular route.…”

Cholera toxin differentially regulates nitric oxide synthesis, tumor necrosis factor-α production and respiratory burst in murine macrophages

“…CT and cholera toxin B subunit (CTB) purified from V. cholerae strain 569B were kindly provided by Dr. R.A. Finkelstein (University of Missouri School of Medicine, Columbia, MO, USA). Monoclonal antibody 4E1G5 reacts with the B subunit of CT [14, 15].…”