REPLICATION OF AUSTRALIAN PORCINE ISOLATES OF ILEAL SYMBIONT INTRACELLULARIS IN TISSUE-CULTURE

Ileal symbiont intracellularis (ISI) isolated from Australian cases of PIA and PHE was replicated in the rat ileum enterocyte cell line IEC 18. The number of TSI within cells varied, as did the number of ISI in fected within the monolayer. At 24 h post infection a large number of cells were infected with approximately 100 ISI per cell. At the termin ation of infection, fewer IEC 18 cells were infected but ISI had repli cated to fill the cell cytoplasmic space. Numerous foci of infected ce lls were visible in the monolayer, containing as many as 15 densely in fected cells. Division of ISI infected cells indicated the transmissio n of ISI in the cytoplasm to daughter cells. This suggests that the re plication of ISI in culture appears to be reasonably cell dependent. N o cytopathic effects were observed in the infected cultures.