[Local immunization against P. aeruginosa with an outer-membrane-protein vaccine]

Averting initial colonization of the respiratory tract with P. aeruginosa would be of great benefit for patients with cystic fibrosis (CF). Our approach to this problem is mucosal immunization with a vaccine prepared from the OMP fraction of a PAO-1 strain of P. aeruginosa. Sprague-Dawley rats were given 5 intragastric doses of the vaccine on 5 consecutive days and an intranasal booster dose 21 days later. Immunized animals developed high titers of OMP-specific IgG antibodies in serum and a specific IgA response in bronchioalveolar and small intestinal lavage samples, all determined by ELISA. When challenged 7 days after the booster (day 28) by intratracheal injection of live bacteria of a heterologous strain of P. aeruginosa the immunized rats showed enhanced bronchopulmonary bacterial clearance compared to nonimmunized controls, as indicated by bacterial counts from homogenized lung tissue taken 4 hrs after challenge. Thus, mucosal immunization with OMP vaccines might hinder initial colonisation of the lungs with P. aeruginosa.