Light microscope and immunohistological investigations on the brain of Borna disease virus-infected rabbits.

We studied the distribution and composition of perivascular cellular infiltrates and the distribution of the virus-specific antigen of Borna disease in the brains of rabbits inoculated either intracerebrally or intraperitoneally with infectious virus suspensions. Using standard histopathological and immunofluorescence techniques, there was, in all animals, a meningeal inflammatory reaction together with perivenous cellular infiltrates which were most numerous in the structures of the limbic system and basal ganglia, but also prominent in the spinal ganglia and area postrema. Studies with fluorescent anti-IgG antibody (direct technique) showed IgG in 20-25% of the cells in any one perivascular cuff, suggesting that most of the infiltrating cells were T-cells and that B-cells were fewer. Studies with virus-specific antibody showed that, in the early stages of the infection, there was evidence of a globular antigen mainly in neurons, while, at later stages, virus antigen was also demonstrated in oligodendrocytes and microgliocytes. The route of inoculation of the virus had no determining effect on the character or distribution of the cellular infiltrates or on the distribution of virus-specific antigen in the nervous system.