DEVELOPMENT OF AN ENZYME-LABELED OLIGONUCLEOTIDE PROBE FOR THE CHOLERA-TOXIN GENE

An alkaline phosphatase-conjugated 30-mer oligonucleotide probe was de veloped to detect the cholera toxin gene (ctx) in Vibrio cholerae O1. For rapid identification, V. cholerae O1 was grown on selective agar ( thiosulfate-citrate-bile salts agar) or in alkaline peptone water and organisms were transferred directly to nylon membranes. Lysis of cells , denaturation of DNA, neutralization, and hybridization were carried out on the membrane. These procedures required only 3 h for completion . The results of the hybridization test with 88 clinical and 20 enviro nmental isolates agreed almost exactly with the results of the immunol ogical tests (anti-cholera toxin antibody-sensitized latex agglutinati on tests). The specificity of the probe was also tested with strains o f enterotoxigenic Escherichia coli, V. cholerae non-O1, and Vibrio mim icus.