Table 1.

RH cyst-like structures, in contrast to conventional tissue cysts, are sensitive to pepsin-HCl digestion

Type of test inoculum (size)No. of mice infected/ no. inoculated (%)a
Undigested inoculumPepsin-HCl-digested inoculumc
RH tachyzoites (106)b 5/5 (100)0/5 (0)
ME49 cysts (50)b 4/4 (100)4/4 (100)
ME49 cysts (5)b 5/5 (100)5/5 (100)
Half brain from STAg-plus-IL-12-vaccinated, RH-challenged mouse6/8 (75)0/8 (0)
Half brain from ts-4-vaccinated, RH-challenged mouse0/4 (0)0/4 (0)
  • a GKO mice were injected with the test inoculum, and 6 to 7 days later peritoneal cells were harvested and microscopically examined for the presence of tachyzoites.

  • b This test inoculum was incubated and injected together with the equivalent of a half brain from uninfected mice.

  • c Digestion with pepsin-HCl was performed for 1 h at 37°C as described in Materials and Methods.