REPRODUCTION OF PORCINE PROLIFERATIVE ENTEROPATHY WITH PURE CULTURES OF ILEAL SYMBIONT INTRACELLULARIS

Porcine proliferative enteropathy is consistently associated with the presence of intracellular curved bacteria in epithelial cells in affec ted portions of intestine. Two strains of these intracellular bacteria were cultured in a cell culture system with rat enterocytes (IEC-18) and passaged several times and used as oral inocula for 14 gnotobiotic and 8 conventional pigs. DNA and immunological studies had identified these bacteria as belonging to a new taxon, Ileal symbiont (IS) intra cellularis. Conventional pigs dosed with approximately 3.7 x 10(6) of these organisms passaged six times in cell culture developed severe le sions of proliferative enteropathy in the ileum. Other conventional pi gs dosed with a lower titer or with organisms passaged 13 times develo ped moderate and minor lesions, respectively. All gnotobiotic pigs dos ed with organisms failed to develop lesions. Control pigs, eight conve ntional and two gnotobiotic, dosed with diluent, uninfected cell mater ial or left undosed failed to develop lesions also. Reisolation of IS intracellularis and demonstration of the organism in mucosal and fecal samples only occurred in conventional pigs dosed with organisms. Gnot obiotic pigs lacking a normal intestinal flora have not been shown to be colonized by the organism. Seroconversion to IS intracellularis or mucosal infiltration by inflammatory cells was not observed in experim entally affected pigs, confirming the weak immune response characteris tic of the natural disease. These results support the identification o f IS intracellularis as an etiological agent of proliferative enteropa thy in pigs.