miR-155 deficiency enhanced cyst burden and reduced survival time in mice models. (A) Survival curves of mice after challenge of cysts of the PRU strain. miR-155^−/− mice had 0% survival at day 17. (B) Cyst loads were counted from whole brain homogenates of mice 4 weeks after challenge. The bars represented the mean cyst burden per mouse brain after challenge orally with a dose of 10 cysts of the PRU strain. Data are mean ± SD (representative of three experiments). **p < 0.01; *p < 0.05, compared with the WT groups.