CHARACTERISTICS OF BORIC ACII) TOLERANT VIBRIO CHOLERAE

Abstract

Two strains of boric acid tolerant Vibrio cholerae have been studied in order to identify the characteristics which distinguish them from the 'wildtype' virulent strains. Strain Ib5 requires either amino acid cysteine or methionine while strain Ib5S requires deoxyribonucleic acid (DNA) for growth. Although the strains did not grow on desoxycholate citrate agar (DCA) they grew well on chocolate agar. Morphologically filamentous, bacillary and comma-shaped forms were seen, depending on the media and incubation period. The strains failed to cause accumulation of fluid in gut ligation and permeability factor tests. With the single radial immunodiffusion test, strain Ib5S gave positive reaction in 83% of the tests when DNA was added to the growth medium. On the other hand only 25% of the tests were positive when no DNA was added to the growth medium, even though the antigen was concentrated ten-fold. Strain Ib5 only gave 50% positive tests when the antigen was concentrated tenfold. It is therefore suggested that Ib5S strain is a choleragenoid producer in the presence of DNA, and may be useful as an effective vaccine against cholerea