Preventive effects of early anti-CD4 or anti-CD8 treatment on Borna disease in rats

Borna disease is a virus-induced, immunopathological encephalomyelitis in which CD4+ cells and Macrophages dominate the pathological picture. However, significant numbers of CD8+ cells have been morphologically identified in perivascular infiltrates as well. To determine the contribution of different T-cell subsets to the pathogenesis of Borna disease, virus-infected rats were treated with Monoclonal Antibodies specific for CD4+ and CD8+ cells. Both types of Monoclonal Antibodies were able to significantly decrease or even prevent the local inflammatory reaction in the brain if given early during the Infection. However, CD8-specific Monoclonal Antibodies appeared to be more effective than antibodies directed against CD4+ cells. Treatment initiated 4 days postinfection did not result in inhibition of Encephalitis and disease. Virus titers in the brain of infected rats treated with T-cell-specific antibodies did not differ from titers in untreated infected control Animals. The results indicate an important functional role of CD8+ cells, in addition to CD4+ cells, in the pathogenesis of Borna disease.