Discrimination of rat-derivedPneumocystis carinii f. sp. cariniiandPneumocystis carinii f. sp. rattiusing the polymerase chain reaction

Abstract

The rat model ofPneumocystis cariniiinfection is widely used for the study of this non-culturable pathogen. Two genetically divergent «special forms» of the organism have been detected in infected rat lungs,P. carinii formae specialis cariniiandP. carinii formae specialis ratti, in some cases as a co-infection. We have developed a simple and rapid method to analyse rat-derivedP. cariniisamples, based on DNA amplification of a portion of the gene encoding the mitochondrial large subunit ribosomal RNA. A pair of oligonucleotide primers were designed for each special form of rat-derivedP. carinii, the RC primer pair amplifying a 137 bp fragment fromP. carinii f. sp. cariniiDNA and the RR primer pair amplifying a 251 bp fragment fromP. carinii f. sp. rattiDNA. The specificity of the primers was confirmed by sequencing the amplification products. The polymerase chain reaction (PCR) technique was consistent with, and more sensitive than, the electrophoretic karyotype method. The application of the specific PCR technique has implications for future studies on epidemiology, drug sensitivity, immunology and molecular biology of rat-derivedP. carinii.