Progressive multifocal leukoencephalopathy: simultaneous detection of JCV DNA and anti-JCV antibodies in the cerebrospinal fluid

We report on a case of biopsy-proven progressive multifocal leukoencephalop athy (PML) in a patient without obvious immunodeficiency. Analysis of the c erebrospinal fluid revealed the simultaneous presence of JC virus DNA and o f locally produced, anti-JC virus antibodies. The intrathecal humoral immun e response increased throughout the course of the disease, whereas the dete ction of the JC genome became ultimately negative in spite of the continuou s extension of the lesions with fatal outcome.