A neutralising monoclonal antibody against a paramyxovirus reacts with a brain antigen

A monoclonal antibody against simian virus (SV5) HN glycoprotein which specifically neutralises the virus cross-reacts in immunofluorescence with an antigen in the cytoplasm of Purkinje cells of adult rat brain. After fixation in acetic acid-ethanol a cross-reaction is also seen with a myelin component. Cross-reaction of this antibody with human brain was also observed on section using immunofluorescence and in tissue extracts using ELISA and radioimmune assays. Monoclonal antibodies against other viruses, against another epitope on the same virus polypeptide and against another SV5 polypeptide of the same isotype were all negative in these tests.