Figure 5
Mice that resolved an initial infection are resistant to reinfection with 108 parasites. (A) Two groups of five mice were pre-exposed to live parasites by intravenously infecting them with a suboptimal dose of 107 parasites per mouse; after 16 weeks, no parasites were detected by in vivo imaging. One group was then reinfected intravenously with 108 parasites (week 0), while the second group served as a control for any possible disease progression from the pre-exposure infection. A third group of naïve control mice was infected intravenously with 108 parasites as a positive control for virulence of the inoculum. By contrast to controls, mice that had been previously exposed to live parasites were immune to subsequent reinfection. Three representative animals from the group are shown and are arranged so that the infection dynamics can be followed in each individual animal throughout the course of the infection. (B,C) Bioluminesence (total flux, photon/sec) were quantified around defined regions of interest corresponding to the liver (B) and spleen (C). Group 1 (red circles, n = 4), Group 2 (white circles, n = 5) or Group 3 (black circles, n = 9) animals. Data points represent means ± S.E.M. of measurements. Relative bioluminescence was calculated by arbitrary normalisation to signals at week 2 (liver) and week 12 (spleen) of naive control-infected animals.
