Distribution of 3beta-hydroxysteroid dehydrogenase in the cerebellum in canine distemper virus infection

The cerebella of eight dogs naturally infected with canine distemper virus (CDV) and two normal dogs were examined immunohistochemically for glial fibrillary acidic protein (GFAP) and 3beta-hydroxysteroid dehydrogenase (3beta-HSD). The clinical diagnosis of canine distemper was confirmed histopathologically and by the immunohistochemical demonstration of CDV antigen. In all dogs (healthy and infected), the Purkinje cells of the cerebellum were immunolabelled for 3beta-HSD activity. In infected dogs, 3beta-HSD labelling was prominent in astrocytes (particularly in areas of astrocytosis) whereas in healthy dogs such immunolabelling was weak. Double immunolabelling demonstrated that all GFAP-positive cells (especially in demyelinating areas) were also positive for 3beta-HSD. The results suggest that 3beta-HSD expression by astrocytes is associated with demyelination in CDV infection.