IFNG and infection: It is important to note that host cells need to be activated by IFN-γ prior to infection to control or even kill the parasite, because T. gondii can otherwise timely prevent up-regulation of IFN-γ-induced effector mechanisms by translocating an effector molecule called T. gondii inhibitor of STAT1-dependent transcription (TgIST) into the host cell (see below).