Abstract
A virus-specific antigen was extracted from brains of rats and from MDCK cells infected with Borna disease (BD) virus and purified to homogeneity by immunoaffinity chromatography and HPLC. The antigen consists of two components which are almost equal in size (38 000 mol. wt.), and it forms aggregates in its native form. The virus specificity of the two antigenic entities was confirmed by immunoblots with convalescent serum and monoclonal antibodies. Immunofluorescent staining with monoclonal antibodies and a hyperimmune serum prepared against the purified antigen showed the intranuclear fluorescence typical for BD virus-infected cells.