Neutralisation of the new cholera toxin by antiserum against crude enterotoxin of cholera toxin gene-positive Vibrio cholerae 01 in rabbit ileal loop model.

The enterotoxicity of the new cholera toxin (NCT) prepared from cholera toxin gene-negative (CT-) V. cholerae 01 strains isolated from human diarrhoeal and environmental sources was assayed in rabbit ileal loops and the toxin unit was calculated to be 24 micrograms of protein. The enterotoxicity of the NCT preparations were completely neutralised by the antiserum raised against the enterotoxin preparation from the CT+ V. cholerae 01 strain 569B at 1 in 16 dilution in ileal loops. The antiserum contained 1 unit of antitoxin in 85 x 10(-4) ml amount. The data indicate that the antiserum prepared against the enterotoxin of CT+ strain contains antibody against the NCT and can neutralise the toxin in vivo. The observations also suggest that CT+ strains liberate the NCT simultaneously with CT and the latter gets eliminated during the process of purification.