Exotoxins of Pseudomonas aeruginosa. II. Concentration, purification, and characterization of exotoxin

Antitoxic sera were produced in rabbits, goats, and ponies with purified exotoxin A of Pseudomonas aeruginosa (strain PA-l03). None of these sera contained agglutinating antibody against the bacterial cells, and all antitoxins appeared in the IgG fraction. Antitoxic titers of pony sera tended to be higher than those obtained with other animals, and 1 ml of these sera neutralized as much as a 5,000 mouse LD50 dose of toxin. The antitoxic sera, when given in sufficient quantity, could prevent the lethal effects of infection caused by strains of P. aeru-ginosa whose somatic antigens were unrelated to those of strain PA-I03, provided the serotype of the exotoxin produced by the organisms was identical. Antitoxin A did not neutralize the cell-bound protein toxins of these organisms. The findings seemed to indicate that neither the cell-bound protein toxin nor the lipopoly-saccharide somatic antigen was an important factor in the pathogenesis of P. aeruginosa. Exotoxin A produced by strain PA-l03 of Pseu-domonas aeruginosa has proved to be sufficiently stable to be concentrated and purified by relatively simple methods [1, 2]. Although efforts to convert this toxin to a toxoid have not been successful, we have produced antitoxin with the toxin itself. This paper describes the procedures that were used in the immunization and the characteristics of anti-toxic sera that were obtained. Materials and Method