Based upon these findings and in vitro studies showing that T. gondii readily invades murine astrocytes and neurons, but only IFN-γ-stimulated astrocytes—not IFN-γ-stimulated neurons—clear intracellular parasites19,21–23, the model of CNS toxoplasmosis was that during natural infection parasites enter the CNS, invade both astrocytes and neurons, after which astrocytes kill the intracellular parasites, leaving the immunologically incompetent neuron as the host cell for the persistent, encysted form of the parasite. The gene discussed is IFNG; the disease is infection.