FIG 3.

R. typhi-infected C57BL/6 RAG1^−/− mice develop lethal neurological disorders and bacteria are present in the brain 3 to 4 months postinfection. C57BL/6 RAG1^−/− mice were infected with 2 × 10⁶ SFU R. typhi either i.v. (n = 10) or s.c. (n = 10). Control mice received PBS i.v. instead (n = 10). Beyond day 80, R. typhi-infected mice developed neurological disorders, often beginning with stroke-like symptoms and resulting in lethal paralysis. (A) Photographs of two representative mice in the early phase (left) and late phase (right) of disease are shown. (B) The percentage of survival (y axis) was assessed for each group at the indicated points in time postinfection (x axis). (C) At the time of death, bacterial loads (y axis) of R. typhi-infected C57BL/6 RAG1^−/− mice that had been infected either i.v. or s.c. were assessed in the indicated organs by qPCR (x axis). SC, spinal cord. Each symbol represents the result for a single mouse. Statistical analysis was performed with the Kruskal-Wallis test. Bars and whiskers show the mean and SEM. Asterisks indicate statistically significant differences (**, P < 0.01). (D) Brains from two mice that were infected with R. typhi s.c. were isolated at the time of death and lysed. Lysates were used to inoculate L929 cells. Cells were incubated for 5 days, and supernatants of these cultures were then used to inoculate L929 cells seeded into chamber slides. Three days later, cells were stained for R. typhi with serum from a patient, anti-human IgG–FITC, and FITC–Alexa Fluor 488-conjugated antibody (green). Nuclei were stained with DAPI (blue).