Agglutinating and precipitating capacity of rabbit anti-Salmonella typhosa gamma G and gamma M-antibodies during prolonged immunization.

Pike, Robert M. (University of Texas Southwestern Medical School, Dallas), Mary L. Schulze, and Cleo H. Chandler. Agglutinating and precipitating capacity of rabbit anti-Salmonella typhosa gammaG and gammaM antibodies during prolonged immunization. J. Bacteriol. 92:880-886. 1966.-Antibody produced in rabbits immunized with acetone-dried typhoid bacilli was followed over a period of 445 days by agglutination and by quantitative precipitation. Repeated injections of vaccine resulted in suppression of antibody titers. Both gammaG and gammaM antibodies were rapidly increased by booster injections after rest periods during which titers had decreased to low levels. The O agglutinin titers and the amount of antibody protein, as determined by precipitation with endotoxin, generally were parallel, except in serum specimens in which unusually large proportions of the agglutinating activity were found in the gammaG fraction. These exceptions were explained by the greater agglutinating capacity of the gammaM. Endotoxin precipitated about 10 times as much antibody from gammaG preparations as it did from gammaM fractions of equivalent agglutinating strength. A much higher proportion of the serological activity, therefore, was found in the gammaG fractions when antibody was measured by precipitation than when agglutination was used as the measure of activity.