DEVELOPMENT OF AN IMPROVED SYNTHETIC MEDIUM FOR A BETTER PRODUCTION OF THE NEW CHOLERA-TOXIN AND ITS IMMUNOLOGICAL RELATIONSHIP WITH THE TOXIN PRODUCED BY VIBRIO-CHOLERAE-O139 STRAINS

An improved synthetic medium (M4) comprising syncase medium supplement ed with sodium chloride (1%) and sucrose (0.5%) pH adjusted to 7.4 was developed for a better production of the new cholera toxin (NCT); The culture filtrates prepared in the M4 medium caused significantly (P < 0.05) more fluid accumulation than that in syncase medium. Crude toxi n, prepared in the M4 medium with V. cholerae 01 strains (X-392 and 27 40-80) caused a reaction similar to that of the same amount of NCT (32 mu g) prepared in the syncase medium. The neutralization of the optim al loop reacting dose of the NCT prepared in the M4 medium by anti-NCT raised against syncase prepared toxin indicates the release of the sa me kind of toxin in both media. These observations indicate that the m odified M4 medium may be used for NCT preparation and further characte rization. All the strains of Vibro cholerae 0139 used in this study pr oduced a toxin antigenically similar to NCT.