SE invasion of COEC and induction of COEC apoptosis. COEC in 48-well culture plates were infected with ZM100 (wt) or ZM106 (pipB) at MOI of 20–30:1. 1A. Number of intracellular bacteria presented as log CFU/well. 1B. Apoptosis of COEC expressed as enrichment factor of mono- and oligonucleosomes in the cytoplasm of COEC. Results shown are geometric means of three independent experiments ± standard deviation. Open bar, ZM100 (wt); solid bar, ZM103 (sipA); hatched bar, ZM106 (pipB). * indicates a significant increase in COEC apoptosis between 1 hpi and 24 hpi (p < 0.05).