IFNGR1 and infection: As an additional test for our hypothesis that IFNγ signaling acts on HSCs during infection, we performed competitive reconstitution assays, using purified LSK cells obtained from wild type (EGFP-transgenic, GFP+, CD45.2+) and IFNγR-deficient mice (GFP−, CD45.2+) (Fig. 6A).