SPECIFIC IN-SITU HYBRIDIZATION OF THE INTRACELLULAR ORGANISM OF PORCINE PROLIFERATIVE ENTEROPATHY

The identity of the intracellular bacteria found in the enterocytes of pigs with proliferative enteropathy was investigated using specific D NA probes to various Campylobacter species and to a novel organism, il eal symbiont intracellularis. The ilea from pigs (Nos. 1-7) that were diagnosed by routine histopathology as having proliferative enteropath y were used. Diagnosis was made on the basis of proliferation of the e nterocytes on hematoxylin and eosin-stained sections and the presence of large numbers of intracellular curved organisms on Warthin-Stany si lver-stained sections. Four of these pigs (Nos. 1-4) had the chronic f orm of the disease, porcine intestinal adenomatosis, and three (Nos. 5 -7) had the acute form, proliferative hemorrhagic enteropathy. An addi tional three normal pigs (Nos. 8-10) were obtained from three separate farms with no history of proliferative enteropathy. Frozen ileal sect ions were examined by in situ hybridization with DNA probes specific f or ileal symbiont intracellularis and the three porcine intestinal Cam pylobacter species, C. coli, C. hyointestinalis, and C. mucosalis. In all seven pigs with either the intestinal adenomatosis or hemorrhagic enteropathy form of the disease, a DNA probe specific for ileal symbio nt intracellularis hybridized to localized foci in the apical cytoplas m of ileal enterocytes. These hybridization sites corresponded to the location of intracellular bacteria in silver-stained sections of adjac ent tissue. Sections from the three normal pigs tested with this probe and from all pigs tested with the Campylobacter species-specific DNA probes showed no specific hybridization reactions. The identity of the intracellular organism in these diseased pigs is ileal symbiont intra cellularis.