Detection of rat Pneumocystis carinii proteinases and elastase and antipneumocystis activity of proteinase inhibitors in vitro

Proteinases play an important role in survival of microorganisms and in pat hogenicity of diseases. By using a modified SDS-gelatin-polyacrylamide gel system, proteinases of rat-P.carinii were detected as bonds of proteolytic digestion after electrophoresis. P.carinii organisms obtained from dexameth azone immunosuppressed transtracheally infected rots were cultured in spinn er Flask suspension cultures to minimize host cell contamination. At pH 8.3 , seven Pc-specific proteolytic bands were detected in three clusters of di fferent molecular weights clearly different from host cell patterns. By usi ng a range of pH, various preparations of organisms and bath infected and u ninfected culture media, proteolytic activities have been partially charact erized. Elastase secretion has been assessed based on elastin digestion mod el. Proteinase inhibitors have been tested for their ability to inhibit P.c arinii growth in HEL299 short-term monolayer cultures. Results indicate tha t proteolytic activities are involved in the proliferation of microorganism s since leupeptin exerted in vitro antipneumocystis activity while aprotini n enhanced P.carinii growth.