Figure 4.

Brain lesions are composed of cells of macrophage lineage. Sections of brain tissue from an untreated infected control animal showing microglial nodules that are composed of cells expressing CD68 (A), which identifies activated macrophages/microglia; Iba-1 (B), expressed by microglia/macrophages; and HLA-DR (C). Localization of SIV major capsid protein p27 in a microglial nodule by IHC (D). Immunoperoxidase immunohistochemistry with DAB chromogen (brown) and hematoxylin counterstain (×100).