FIG 4.

T. foetus induces contact-dependent activation of apoptosis in intestinal epithelial cells. (A) Immunoblot of IPEC-J2 cells for the M30 antigen of cleaved cytokeratin 18 after incubation with T. foetus for 6, 12, 24, and 36 h (termed IPEC-J2 + Tf). (B) M30 was not detected in isolated T. foetus trophozoites in either log-phase cultures (early) or overgrown cultures containing large numbers of dead organisms (late). (C) Immunoblot for the M30 antigen following 36 h of coculture of IPEC-J2 monolayers in direct contact with T. foetus, indirect contact with T. foetus (filter separated), or T. foetus conditioned media. Each condition was performed in triplicate. The positive control (+) is IPEC-J2 cells postinfection with Cryptosporidium parvum.