As miR-155 has been shown to be critical for regulating T-cell responses as well as inflammatory responses and cytokine signals, which have well-documented roles in the control of intracellular pathogens, including T. cruzi and Leishmania donovani [16, 30], we further analysed the production of cytokines Th-1-associated IFN-γ, IL-2, Th-2-associated IL-4 and IL-13, Th-17-associated IL-17A and IL-17F by splenic cells harvested from WT and miR-155KO (miR-155−/−) mice after infection with T. gondii PRU cysts. This evidence concerns the gene IL17A and infection.