Figure 1.
A–C, Pathology in mice infected with Chlamydia psittaci 6BC/B. DBA2/J mice were infected intraperitoneally (104 inclusion-forming units [IFU]) and euthanized on day 7 after infection for histological analysis. (A) Lung: infiltration of inflammatory cells in the interstitial tissue and serosa. B, Heart: inflammatory cells in the pericardium. C, Liver: thick layer of inflammatory cells on surface and microabscess in the parenchyma. D, Lethal dose determination of C. psittaci 6BC strains. Original and clonal stocks of virulent C. psittaci 6BC/B and attenuated C. psittaci 6BC/H were prepared at inocula of 102–105 IFU and injected intraperitoneally. Percentage of mice (n = 5) that survived challenge is shown.