Passive protection of mice against intraperitoneally injected Vibrio cholerae by G and M antibody.

Fractions of rabbit anti-Vibrio cholerae serum containing gammaG antibodies were compared with fractions containing gammaM antibodies for their ability to protect mice against lethal infection resulting from the intraperitoneal injection of organisms suspended in mucin. About twice as much gammaG as gammaM (estimated by quantitative precipitation) was required to protect against approximately 1,000 50% lethal doses when the antibody was given intraperitoneally 4 hr before challenge. When protective serum fractions were given subcutaneously, however, the amount of gammaM required to protect was increased about 40-fold, whereas gammaG was about equally effective subcutaneously and intraperitoneally.