The effect of local and systemic immunization of suckling pigs on bronchoalveolar clearance and on intrabronchial infections with Pasteurella multocida

In vivo investigations of bactericidal bronchoalveolar clearance of weaning pigs locally or systemically immunized with Pasteurella antigens exhibited clearly distinctive results, as early as 3 days after the last immunization. They differed from controls by significant increase in the elimination of the homologous Pasteurella multocida A wild strain. That increase in the clearance remains for 21 days and is specific only to the immunized capsular type. There are no relations of this result to the cytological findings of the lavage fluids and to results of the intrabronchial challenge infection. Frequency and severity of pneumonias were reduced by as little as 3 aerogenic immunizations with Pasteurella mutants.