Figure 5. Ritonavir treatment initiated after disease onset protects the hippocampus and prevents escalation of behavioral seizures.

Mice were treated with oral ritonavir (RIT) or vehicle (VEH) every 6 hrs starting at 36 hours postinfection. VEH mice showed extensive hippocampal injury at 7 dpi (a,c) but RIT mice were protected (b,d). Most of the CA1 neurons in RIT mice were intact (b) and maintained apical dendrites (arrows in d). Images are representative of 10 mice per group in two separate experiments. (e) Quantitation of hippocampal injury revealed that VEH mice had almost complete bilateral damage to CA1 (0 = no damage; 10 = 50% bilateral damage or 100% unilateral damage; 20 = 100% bilateral damage), while most RIT mice had only mild or moderate injury. P < 0.001 by t-test; n = 10 per group; representative of more than 40 mice in three separate experiments. (f) Body weights were not different between VEH (open circles) and RIT (filled inverted triangles) mice. P = 0.923 by two-way RM-ANOVA; n = 10 per group. (g) Behavioral seizures were quantified as described in the methods. The total number of Racine events manually observed between 0 and 7 dpi (P < 0.001 by Fisher exact test; n = 10 per group) and the total number of Racine events detected by video at 3 and 7 dpi (P = 0.136 at 3 dpi; P = 0.001 at 7 dpi by Fisher exact test; n = 10 per group in two experiments) were reduced in RIT mice. (h) Maximum Racine score observed each day in VEH (open circles) and RIT (filled inverted triangles) groups is shown. Both groups started with 10 mice; 3 VEH mice died (black circles) during the experiment; no RIT mice died. Ritonavir suppressed seizures from 3 dpi until the end of the experiment (132 dpi); P < 0.001 between treatments by two-way RM-ANOVA; day 4-132 significant at P < 0.001 by SNK pairwise analysis; 3 dpi significant at P = 0.023. Scale bar in (b) is 500 μm and refers to (a) Scale bar in (d) is 100 μm and refers to (c). Graphs show means ± 95% confidence intervals.