The cerebrospinal fluid of rabbits infected with Borna disease virus.

Rabbits were inoculated intracerebrally with Borna disease virus infected brain suspension or tissue culture extracts. In 30 per cent of the diseased animals infectious virus was present in the cerebrospinal fluid (CSF). The CSF had increased numbers of lymphocytes and an elevation of the protein concentration, mainly due to an increase in gamma-globulins, was measured. The gamma-globulins were of oligoclonal character and reacted with a borna disease virus specific antigen of infected brains or tissue culture cells. The antibody titers in the CSF were of similar level to those in the serum. In comparison, those of the CSF of naturally infected horses always exceeded the serum titers. Injection of tracer substances revealed that no drastic damage to the blood-brain barrier was caused during the disease. The results suggest that antibodies detected in the CSF are locally produced. The significance of these findings for the pathogenesis of Borna disease is discussed.