It is hypothesized that IFN-γ contributes to the initiation of tissue cyst formation in vivo, as it can induce cystogenesis in vitro (described above), however IFN-γ knockout mice fail to control acute proliferation of parasites and succumb to acute infection (Suzuki et al., 1988; Suzuki et al., 1989) even when infected with avirulent strains of T. gondii (Coombs et al., 2020) making it difficult to determine if IFN-γ induces cystogenesis in vivo. This evidence concerns the gene IFNG and cyst.