IFNG and Splenomegaly: Strikingly, despite uncontrolled hepatic parasite growth, as reported in IFNγ-deficient mice [63], mice lacking IFNγ receptor (IFNγR) showed no splenomegaly and complete preservation of MZM after 28 days of infection when MZM were lost in C57BL/6 controls (Fig 8A–8D).