Cetacean-morbillivirus (CeMV)-associated lesions in central nervous system of striped dolphins (Stenella coeruleoalba), bottlenose dolphins (Tursiops truncatus), and Guiana dolphins (Sotalia guianensis).

(A) Cerebral meningoencephalitis (case 14). The leptomeninges are inflamed and there is increased cellularity in the underlying cortex and subcortical white matter. A large perivascular cuff (arrow) and a few spongy foci (asterisk) are noted. 20x. H&E. Right upper inset: small lymphocytic and plasmacytic perivascular cuff in the cerebral cortex (case 14). 400x. H&E. Right middle inset: thick perivascular cuff at the gray/white matter interface (case 18). 200x. H&E. Right lower inset: degenerating neuron cell body with microglial neuronophagic nodule (case 19). 400x. H&E. (B) Cerebellar meningoencephalitis (case 13). Diffusely, the pia mater, arachnoid, and dura matter are infiltrated by mononuclear inflammatory cells. 40x. H&E. Left inset: mononuclear inflammation at molecular, Purkinje cell, and inner granular cell layer interface with edema, rarefaction, and focal multinucleate giant cell/syncytial cell (MGCS; arrow) (case 19). 200x. H&E. Right inset: Less severely inflamed cerebellar interface area with three degenerating Purkinje cells, one of which displays a viral intranuclear inclusion body (arrow) (case 19). 400x. H&E. (C) Cerebral cortex (case 26). Degenerating swollen neurons and necrotic neurons with intranuclear and intracytoplasmic viral inclusion bodies. 400x. H&E. Right upper inset: Degenerating swollen astrocyte with intracytoplasmic inclusions. 400x. H&E. Right lower inset: Degenerating neuron with intranuclear inclusion body and adjacent necrotic neuron. 400x. H&E. (D) Cerebral cortex (case 26). Marked positive labeling for CeMV-antigen (red) in degenerating neurons and fewer astrocytes (GFAP-brown) (arrow). There is loss of astrocytic processes and cell bodies in this focus. 400x. Double IHC for CeMV and GFAP. (E) Cerebral cortex (case 26). Moderate labeling for CeMV-antigen in neurons and less so in astrocytes (arrow). There is relative preservation of astrocytes in this focus compared to figure (D) but those present have plump nuclei, cytoplasm, and processes. Note astrocytic processes reaching the perivascular space show occasional positivity for CeMV as well. 400x. Double IHC for CeMV and GFAP. (F) Cerebellum (case 1). There is positive labeling for CeMV-antigen in endothelium focally and adjacent neuroglia. 400x. IHC for CeMV. Inset: CeMV positive labeling in neuronal soma and axon hillock of frontal cerebral cortex (case 9). 400x. IHC for CeMV.