[Sensitization against the antigens of the brain after experimental vaccinia infection. II. Humoral anti-brain antibodies and morphological changes in the CNS (author's transl)].

29 guinea pigs, strain Pirbright, were infected with vaccinia virus, strain Elstree, by the dermal route. The observation period was 14 days. Thereafter, the animals were killed and their central nervous systems (CNS) histologically and immunohistologically, the blood fluorescence-serologically examined. Histological examination revealed meningitis, ependymitis or disseminated meningoencephalitis with slight perivascular cuffing in 72% of the animals. The viral antigen was found in 3 animals (10%). It was present most often in the cytoplasma of the arachnoidal and/or ependymal cells, as well as in the cells of the vessel walls and less often in the glial and/or nerve cells. The infected cells showed no severe degenerative changes. The blood-brain-barrier displayed localized disturbances. The examination of the myelin sheaths revealed disseminated foci of disappearance of myelin fluorescence in the perivascular, paraventricular and subcortical regions. Antibodies directed against myelin sheaths, or nerve cells could be detected in the sera of 48% of the animals. The results give evidence that the vaccinia infection is capable to induce a potentially pathogenic autoimmune reaction directed against brain. Such an immunomechanism can be triggered without any signs of acute lytic infection of the CNS. The mechanism and significance of this reaction are discussed.