MOLECULAR ANALYSIS OF RIBOSOMAL-RNA AND CHOLERA-TOXIN GENES CARRIED BY THE NEW EPIDEMIC STRAIN OF TOXIGENIC VIBRIO-CHOLERAE-O139 SYNONYM BENGAL

Vibrio cholerae 0139 synonym Bengal recently caused large epidemics of cholera-like disease in Bangladesh and India. We compared the restric tion fragment length polymorphisms of ctxA and rRNA genes (ribotypes) in 27 isolates of V. cholerae 0139 from patients in Bangladesh and Ind ia with those of 48 isolates of V. cholerae 01 from patients and 21 V. cholerae isolates from surface waters in Bangladesh, which included 2 0139 and 19 other non-01 isolates. Ribotyping of the isolates with Bg lI revealed that all 29 isolates of 0139 vibrios belonged to a single ribotype, suggesting a clonal nature of the infection. However, the 01 39 vibrios comprised two ctxA genotypes and carried three or more copi es of the ctxA gene, and the chromosomal locations of these copies wer e unlike those of the El Tor or classical vibrios. Analysis of the res triction fragment length polymorphisms of the rRNA genes suggested tha t V. cholerae 0139 isolates are more closely related to El Tor strains of V. cholerae 01 than were 19 other non-01 vibrios and 33 classical V. cholerae 01 isolates that were studied. However, further studies ar e needed to determine whether V. cholerae 0139 originated from mutatio ns and genetic changes in a V. cholerae 01 strain or was due to the ac quisition of virulence genes by a previously unknown V. cholerae non-0 1 strain.