AIF1 and infection: Notably, peripheral hemoglobin-haptoglobin receptor CD163 was confined to Iba1 + cells in the intravascular space, which is consistent with prior primate studies in macaques that have identified CD163 as a selective marker of perivascular macrophages that is not observed in parenchymal cells in healthy animals but is found intraparenchymally following BBB breakdown in simian-immunodeficiency virus (SIV)-infection [47, 48].