Real-time PCR assay for screening Pneumocystis in free-living wild squirrels and river rats in Italy

We used a real-time PCR (rtPCR) targeting a 150-bp amplicon of the mitochondrial small subunit of ribosomal RNA (mtSSU rRNA) to screen for Pneumocystis DNA in lungs of wild squirrels (Callosciurus finlaysonii, n = 85) and river rats (Myocastor coypus, n = 43) in Italy. The rtPCR revealed Pneumocystis DNA in 20 of 85 (24%) squirrels and in 35 of 43 (81%) river rats, and was more sensitive than a nested PCR that targets a portion of the mtSSU rRNA and the mitochondrial large subunit of rRNA (mtLSU rRNA). Phylogenetic analysis based on mtSSU rRNA and mtLSU rRNA sequences showed distinct Pneumocystis sequence types in these rodents. The rtPCR assay should be reliable for screening large populations for this potential pathogen, thereby allowing cost-effective monitoring of the disease in wild animals.