HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology



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

J.A. Ramos Vara1, J-J. Lu2, A.J. da Silva4, K.T. Montone5, N.J. Pieniazek4, C-H. Lee3, L. Pérez5, B.A. Steficek1, R.W. Dunstan1, D. Craft6 and G.L. Watson1

1Animal Health Diagnostic Laboratory, Michigan State University, East Lansing, MI, USA, 2Department of Pathology, Tri-Service General Hospital, Taipei, Taiwan, 3Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, In, USA, 4Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA, 5Department of Pathology and Laboratory Medicine, University of Pennsylvania, Medical Center, Philadelphia, PA, USA and 6Department of Pathology, Michigan State University, East Lansing, MI, USA

Offprint requests to: Dr. José Ramos-Vara, Animal Health Diagnostic Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, MI48824, USA

 

Summary. Macroscopic, histologic, ultrastructural, microbiologic, in situ hybridization (ISH) and PCR detection results in three 8-week-old pigs naturally infected with Pneumocystis carinii (PC) are described. All animals had a nonsuppurative interstitial pneumonia and intra-alveolar Pneumocystis organisms with foamy eosinophilic and PAS positive appearance. Ultra-structurally, PC trophozoites and cysts were observed in pigs No. 2 and No. 3, with the former being much more numerous. PC organisms were located on the alveolar surface or within the alveolar septa. Trophozoites had numerous filopodia and were thin-walled. Cysts had no or few filopodia, were thick-walled and contained intracystic bodies. Using non-isotopic ISH on formalin-fixed, paraffin-embedded lung tissue sections, PC DNA from pigs No. 2 and No. 3 hybridized with a probe specific for PC ribosomal RNA (rRNA). Using primers specific for mitochondrial rRNA gene (pAZ102-E/pAZ102-H), and for the internal transcriber spacers 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-fixed and paraffin-embedded lung tissue. DNA from Pig No. 1 samples did not amplify with any primer. This is the first time that molecular biology techniques (in situ hybridization and PCR) have been applied to the study of porcine pneumocystosis. Histol Histopathol 13, 129-136 (1998)

 

Key words: Pneumocystis carinii, Pneumonia, Electron microscope, ISH, PCR

DOI: 10.14670/HH-13.129