a–d, Growth of C. pneumoniae in host cells monitored by quantification of dnaK transcription by real-time PCR. Host cells were infected for one hour at a multiplicity of infection (m.o.i.) of 10:1 followed by incubation in fresh media containing the inhibitors. Each of the assays was repeated 3–10 times. Student’s t-test was performed between treated and untreated cells. a, BGMK cells treated with compounds 0433YC1 (P = 0.0004) and 0433YC2 (P = 0.000001) at 10 µg ml−1. Standard growth medium and that plus chloramphenicol (Cm) were used as growth and inhibition controls. b, Hep-2 cells treated with 0433YC2 (P = 0.0016) at 10 µg ml−1. c,BGMK cells treated with compounds at the designated concentrations (µM) on the×axis. d, BGMK cells were first treated with chloramphenicol or 0433YC2 for 72 h. The compounds were then removed and dnaK levels were determined after an additional 48 h. Data in a–d are presented as total copy number of dnaK transcripts per well of the 24-well plate (mean + s.e.m.). e–h, Immunofluorescent images of BGMK cells infected with C. pneumoniae at an m.o.i. of 10:1. The C. pneumoniae inclusions are stained with anti-Chlamydia-LPS antibody (green) and the host cell is counterstained red. Cells were treated with e, 0433YC1, f, 0433YC2, g, media control, or h, chloramphenicol.