Figure 4D confirms that the α-CD45-APC antibody was efficient at staining intravascular leukocytes. We found an increase in the number of both extravascular (unpaired t-test, p-value = 0.0482, t=2.813, df = 4) and intravascular (unpaired t-test, p-value = 0.0160, t=4.0007, df = 4) CD45+ cells upon 1/148 infection, but not upon IL3000 infection (Figure 4—figure supplement 1), suggesting that the immune response is much stronger in the acute strain. Additionally, the contribution of intravascular leukocytes to the total immune cells in the brain is higher in infected animals (14%±4 vs 25%±1). The gene discussed is APC; the disease is infection.