INTRANASAL INOCULATION OF MOUSE, RAT OR RABBIT-DERIVED PNEUMOCYSTIS TO SCID MICE

Pneumocystis carinii is a widespread opportunistic agent found in the lungs of mammals. This organism causes severe pneumonia in immunocompr omised hosts. Antigenic genomic and karyotypic host-species related di fferences have been reported among P. carinii isolates. Nevertheless, it has not been proved if Pneumocystis from a given mammal can infect other host species. We have then attempted to infect P. carinii -free SCID mice with either mouse, rat or rabbit-derived P. carinii isolates by nasal instillation. Forty and 90 days post-inoculation, only SCID mice instillated with mouse-derived parasites developed P. carinii pne umonia (PCP). Our findings suggest that P. carinii exhibits strong hos t species specificity. Furthermore, cross infection experiments would be a useful tool in the identification of Pneumocystis species, and in the epidemiology of PCP.