Penicillin G-Induced Chlamydial Stress Response in a Porcine Strain of Chlamydia pecorum

Figure 2

Penicillin G exposure induces aberrant body formation and reduces infectious elementary body production in Chlamydia pecorum. C. pecorum-infected HeLa cells were exposed to penicillin G (PenG), at 0 hours postinfection (hpi) until 35 hpi. Control infected cells were exposed to diluent only (mock). Cycloheximide was included (a) or not included (b) in the incubation medium. Inclusions were visualized using an antibody directed against chlamydial lipopolysaccharide (green), and DNA was labeled with 4′,6-diamidino-2′-phenylindole dihydrochloride (blue). Percent of host cells infected and mean nuclei per field was determined by evaluation of 10 fields (≥200 cells), per coverslip, per sample. Representative immunofluorescence and transmission electron microscopic images illustrate normal inclusions in mock-exposed controls and inclusions containing aberrant bodies upon penicillin exposure. Infectious elementary body production was determined by titration by subpassage and expressed as inclusion-forming units (IFU)/mL. Results are means ± standard deviation. The two-tailed t-test was used to compare means; p ≤ 0.05 = significant ; (a) or (b). Scale bars = 5 μm.

(a)

(b)