AIF1 and viral infectious disease: H&E staining and IHC stains to highlight neuronal axons/dendrites (neurofilament protein [NFP]), myelin (MBP), astrocytes (GFAP), and microglia/macrophages (IBA1) revealed the spectrum of PML pathology with regard to destruction of endogenous tissue, evidence of viral infection (enlarged oligodendrocytes with glassy, eosinophilic nuclear inclusions), altered cellular composition and morphology, and loss of axons and myelin (Fig 2; Table 1).