IMMUNIZATION WITH PNEUMOCYSTIS-CARINII GPA IS IMMUNOGENIC BUT NOT PROTECTIVE IN A MOUSE MODEL OF PNEUMOCYSTIS-CARINII PNEUMONIA

Immunization with whole Pneumocystis carinii has been shown to protect mice from the development of P. carinii pneumonia (PCP) when they are subsequently immunosuppressed and challenged with viable organisms. T o determine whether these results could be duplicated by using a subun it vaccine, we examined the immunogenicity and efficacy of an immuniza tion strategy based on P. carinii gpA, This antigen was chosen for stu dy because passive immunoprophylaxis, based on gpA, has been shown to be partially protective in various animal models of infection, Immuniz ation with gpA produced an anti-gpA specific antibody response compara ble to that resulting from immunization with whole organisms. However, in contrast to immunization with whole P, carinii, which was protecti ve, immunization with gpA did not protect T-cell-depleted mice from th e development of PCP, These studies suggest that other antigens in add ition to gpA need to be evaluated for their role in protective immunit y against P, carinii.