Effect of INPs on Chlamydia intracellular development and entry. (A) HeLa cells infected with C. trachomatis L2 (top) or C. caviae GPIC (bottom) were grown in the presence of INP0341 for 24 h at the concentrations indicated. After fixation, bacteria were labelled with anti-EfTu antibody (green) and host cell nuclei were stained with Hoechst 33342 (blue). (B) HeLa cells were infected with C. trachomatis L2 or C. caviae GPIC for 2.5 h in the presence or absence of 60 μM INP0400 or INP0341 and extracellular and intracellular bacteria were differentially immunolabelled as previously described . The number of extra- and intracellular bacteria in untreated and treated cells were counted in 15 fields with an average of 75 bacteria per field. The efficiency of entry is expressed as the ratio of intracellular to total cell-associated bacteria (intracellular and extracellular). The data shown represent the average and the standard error of 30 fields from two independent experiments.