Further evidence of host species-specific variation in antigens of Pneumocystis carinii using the polymerase chain reaction.

To further elucidate the extent of variation among Pneumocystis carinii obtained from different mammalian hosts, polymerase chain reaction (PCR) analysis of the genes encoding two antigens of P. carinii was done. Using primers based on the ferret P. carinii glycoprotein (gp)A gene and the rat P. carinii 45- to 55-kDa antigen gene, amplification was attempted with DNA isolated from P. carinii-infected ferret, rat, mouse, and human lungs. For both genes, amplification was successful only with P. carinii DNA isolated from the same host species from which the P. carinii gene was originally isolated. The presence of P. carinii DNA in each sample was documented by PCR using primers based on the conserved mitochondrial ribosomal RNA gene sequence. These results were confirmed for P. carinii gpA by Southern blot analysis using a labeled fragment of the ferret P. carinii gpA gene as a probe. Thus, in addition to the previously reported phenotypic variation among antigens of P. carinii, there is also genotypic variation of these same antigens.