IFNG and toxoplasmosis: To determine if ROP5 deficient (RHΔku80Δrop5) parasites were controlled by an IFN-γ-dependent mechanism, we tested the virulence of ROP5 deficient (RHΔku80Δrop5) parasites in Ifngr1−/− mice, which are unable to respond to IFN-γ and hence, are highly susceptible to toxoplasmosis [32].