Consistent with this, microglia, but not macrophages, from TLR4-/- animals express lower levels of MHCII under homeostatic conditions, prior to infection (Figure 6D,E and Figure 6—figure supplement 1B) and lower total numbers of MHCII expressing microglia (and total microglia) during JHMV infection when compared to WT mice (Figure 6F and G). This evidence concerns the gene TLR4 and infection.