NUCLEIC-ACID DETECTION AS A DIAGNOSTIC-TOOL IN POLYOMAVIRUS JC INDUCED PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY

Procedures involved in the diagnosis of JC virus central nervous syste m infection range from detection of virus specific products in biopsy material to demonstration of viral DNA in cerebrospinal fluid by PCR. Despite the fact that PCR is the most sensitive method for the detecti on of virus in clinical specimens, diagnostic evaluation is increasing ly difficult in view of the possible subclinical activation of persist ent JCV infection in the central nervous system of high risk patients. Therefore, PML diagnosis by molecular detection of JCV DNA in biopsy material was compared with diagnosis by PCR on CSF of patients with an d without PML. Evaluation of the diagnostic techniques revealed that s tereotactic biopsy based PCR diagnosis at present combines speed and s ensitivity with the highest specificity available. Although the non in vasive technique of JCV detection in CSF by PCR is even more sensitive leading to detection of about 20 genome equivalents per 1 mu l of CSF , the specificity of the method is limited by subclinical presence of JCV DNA in CSF of neurologically asymptomatic HIV infected patients. A dditionally, autopsy proven PML cases remaining JCV negative in PCR on CSF become a common finding. Therefore, in cases where biopsy is not performed, diagnosis of PML can only be achieved in combination with n eurological and radiological diagnosis. (C) 1998 Wiley-Liss, Inc.