DNA immunization followed by a viral vector booster in a Chlamydia pneumoniae mouse model.

Vaccination against Chlamydia pneumoniae would be a beneficial strategy for either preventing or controlling infection by this human respiratory pathogen that also causes persistent infections. In the present study, we used recombinant Semliki Forest virus (rSFV) particles for delivering C. pneumoniae antigens major outer membrane protein (MOMP) or outer membrane protein 2 (Omp2) to the mice or applied the prime-boost technique, where mice were first primed with naked DNA and then boosted with the viral vector coding for the same proteins. Partial protection suggested by the reduced number of cultivable bacteria from the lungs of the challenged mice was seen in mice immunized by either method with MOMP expressing constructs. A significant protection was also achieved after DNA/rSFV immunization with Omp2. DNA priming followed by rSFV boosting induced a more prominent IFN-gamma production after challenge at the site of the infection in pulmonary and mediastinal cells.