Figure 4. Experimental protocol for study of Rickettsia prowazekii persistence and reactivation in BALB/c mice.
BALB/c mice were infected intravenously (via the retro-orbital venous plexus) with 1×105 bacteria. Doxycycline was administered to group 1 (*) per os on days 7 and 9. Two months following the primary infection, mice were immunosuppressed with dexamethasone or cyclosporine via the intra-peritoneal route. A control group received sham immunosuppression with phosphate buffered saline. To study bacterial persistence, infected mice were sacrificed at days 20 (n = 2 mice), and 97 (n = 2) post-challenge and the presence of bacteria in different organs was assessed by PCR, cell culture, and immunostaining. Mice sacrificed at 120 days post-infection (n = 11) were infected in a separate experiment and bacterial persistence was evaluated by the same techniques.