TSPO is shown in three cases of HIVE (A–C). The staining is with the pAb unless indicated otherwise. The microglial nodule shown in A is laden with TSPO+ perivascular cells and TSPO+ astrocytes are present. In all panels, TSPO+ astrocytes are indicated with arrowheads and cells were identified based on morphology. The microglial nodule shown in B is full of TSPO+ multinucleated giant cells. The area shown in (C), away from a microglial nodule, shows TSPO+ astrocytes adjacent to a vessel. (D) Perivascular TSPO+ cells are shown in an SIV+ brain without encephalitis. TSPO+ perivascular cells are also present in SIV− brain (not shown). (E) illustrates TSPO+ oligodendrocytes, based on the typical linear arrangement. (F) displays ramified microglia (based on morphology) observed throughout the parenchyma in one SIVE brain. One TSPO+ cell is shown in high power in the inset of (F). (G–J) are serial sections of the same microglial nodule stained for CD68: (G), SIV GP41 (H), the TSPO mAb (I) and the TSPO pAb (J). The scale bar represents 40 μm in A–F, 80μm in G–J and 12 μm in F inset.