Oral immunization of mice with temperature-sensitive Pseudomonas aeruginosa enhances pulmonary clearance of the wild-type.

DBA/2J mice were immunized daily for 3 days per os with 10(8)-10(9) colony forming units (c.f.u.) of two different temperature-sensitive (TS) mutants of Pseudomonas aeruginosa. At varying times after the final immunization the animals were exposed to aerosols of the parental immunotype 1, and the ability of the immunized and control mice to clear their lungs of the wild-type (WT) challenge was measured 4 h later. The number of c.f.u. remaining in the lungs of mice immunized with one mutant, D/1/8, was significantly less (p less than 0.01) than the number remaining in the lungs of control mice and mice immunized with a second TS mutant, E/9/9.