Multiple neural cell types are infected in vitro by border disease virus

Border disease (BD) of sheep results from a congenitally acquired nonarbotogavirus infection which causes a highly selective central nervous system (CNS) pathological lesion consisting of diffuse decreased myelination without inflammation or neuronal destruction. Thus, a selective disruption of oligodendroglial function appears to occur. In order to investigate the in vitro cell tropism of BD virus, primary cultures derived from fetal and adult ovine CNS and peripheral nervous system were inoculated with BD virus. Infected cell types were determined by dual immunofluorescent labeling for viral and cell type specific antigens. Infection of all the major cell types represented in these cultures, including oligodendrocytes, astrocytes, fibroblasts, dorsal root ganglion neurons and Schwann cells was found. Oligodendrocytes were only infected earlier and appeared to remain infected longer than astrocytes and fibroblasts. Infectious virus was produced by all cultures and continued to be produced even after the disappearance of nearly all immunocytochemically detectable viral antigen within cells. These studies suggest that the selective dysfunction of the oligodendrocyte in BD is not based on a selective viral tropism.