Canine distemper virus-associated encephalitis: modification by passive antibody administration.

Gnotobiotic puppies were intraperitoneally infected with R252-canine distemper virus (CDV), and treated with normal serum (NS) or CDV-specific antibody. Resultant central nervous system (CNS) lesions were evaluated by light and immunofluorescence microscopy. Lesions in NS-treated dogs, if present, consisted of small foci of neuronal degeneration and accompanying microgliosis, restricted to grey matter of the frontal lobe. Dogs receiving anti-CDV antibody, in contrast, had extensive lesions in the brain. Laminar cortical necrosis, gliosis and astrocytic activation of the grey matter of the frontal lobe was the most consistent lesion observed. In addition, foci of cerebellar granule cell layer degeneration and necrosis was seen along with segmental poliomalacia of the spinal cord. In several dogs, eosinophilic intracytoplasmic and intranuclear viral inclusion bodies were observe in neurons. The lesions observed in these dogs are compared to previously reported lesions of CDV infection in dogs.