Figure 3.

Immune protection against R. rickettsii infection. C3H/HeN mice were immunized 3 times with rYbgF, rTolC, WCA, or PBS. At day 14 after the last immunization, mice were challenged with R. rickettsii. At day 6 after challenge, mice were sacrificed and their spleens (A), livers (B), and lungs (C) were collected for use in qPCR assays. Rickettsial DNA copies among groups are expressed as mean copies + standard deviations. The statistically significant differences between PBS immunized mice and other groups were analyzed using the T test or Wilcoxon Two-Sample Test based on their normality and equality of variances and are indicated as follows: *, P < 0.05; ***, P < 0.001; ns, no significance. ^*P < 0.05; ^**P < 0.01; ns, no significance, respectively.