The rat model of Pneumocystis carinii infection is widely used for the stud
y of this non-culturable pathogen. Two genetically divergent 'special forms
' of the organism have been detected in infected rat lungs, P. carinii form
ae specialis carinii and P. carinii formae specialis ratti, in some cases a
s a co-infection. We have developed a simple and rapid method to analyse ra
t-derived P. carinii samples, based on DNA amplification of a portion of th
e gene-encoding the mitochondrial large subunit ribosomal RNA. A pair of ol
igonucleotide primers were designed for each special form of rat-derived P.
carinii, the RC primer pair amplifying a 137 bp fragment from P. carinii f
. sp. carinii DNA and the RR primer pair amplifying a 251 bp fragment from
P. carinii f. sp. ratti DNA. The specificity of the primers was confirmed b
y sequencing the amplification products. The polymerase chain reaction (PCR
) technique was consistent with, and more sensitive than, the electrophoret
ic karyotype method. The application of the specific PCR technique has impl
ications for future studies on epidemiology, drug sensitivity, immunology a
nd molecular biology of rat-derived P. carinii. (C) 1999 Academic Press.