IFNAR1 and infection: For instance, in this model and in contrast to Py YM infection, the burst of systemic type I IFN occurs much later (day 4 versus day 1.5), parasitemia stay very low (1.5% versus ~60% iRBCs by day 4), and significant differences in MHC class II expression on WT versus Ifnar1-/- monocytes are reported, altogether supporting the idea that immune cells are exposed to very different milieus both at early and late times post infection.