Purification and Initial Characterization of a Ferret Pneumocystis Carinii Surface Antigen

The purification and initial characterization of a ferret Pneumocystis carinii surface glycoprotein is described. Previous studies have demonstrated that passive administration of monoclonal antibody recognizing this glycoprotein reduces the severity of P. carinii pneumonitis in animal models of infection. This acidic glycoprotein (approximate isoelectric point, 5.0-5.7) contains both mannose (and/or glucose) and N-acetyl-glucosamine residues. The cross-reactive surface antigen on P. carinii of human origin is also a mannose- (and/or glucose-) containing glycoprotein. Initial biochemical characterization of these surface molecules should aid in understanding the immunobiology of this organism and in developing reliable diagnostic assays for P. carinii pneumonitis.