Characterization of natural occurring Pneumocystis carinii pneumonia in pigs by histopathology, electron microscopy, in situ hybridization and PCR amplification

Abstract

Macroscopic. histolog ic . ultrastruc tural. microbiologic. ill sirll hybridi za ti on (ISH ) and PCR detection results in three 8-week-old pi gs naturall y infected with Pllel.llllonsris c{lrinii (PC) are described . All an imals had a nonsu ppurati ve interstitial pneumoni a and intra-alveolar PlleulIlucysris organisms with foamy eos in ophili c and PAS positi ve appearance . Ultrastructurally. PC trophozoites and cysts we re observed in pigs No.2 and NO .3. with the fo rmer being much more numerous. PC organisms we re located on the alveolar surface or within the alveolar septa . Trophozoites had numerous filopodia and were thin-wall ed. Cysts had no o r few filopodia. we re thick- wa ll ed and co nt a ined intracysti c bodies. Using non-isotopic ISH on formalinfixed. paraffin-embedded lung tissue sections. PC DNA from pigs No.2 and No . 3 hyb ridi zed with a probe specific for PC ribosomal RNA (rRNA). Using primers spec ific for mit oc ho ndrial rRNA ge ne (pA Z I0 2- E/pAZ I 02-H). and for the interna l transcriber space rs of ribosomal gene of PC. PCR methods amplified a product in the lung of pigs No.2 and No.3 using either frozen or formalin -fi xed and paraffin -embedded lung tissue. DNA from Pig No. I samples did not amplify with any primer. This is the first time that molecular biology techniques (ill siru hybridi zation and PCR) have been applied to the study of porc ine pneumocystosis.