Quantification of JC Virus DNA in the Cerebrospinal Fluid of Patients with Human Immunodeficiency Virus—Associated Progressive Multifocal Leukoencephalopathy—A Longitudinal Study

In progressive multifocal leukoencephalopathy (PML) the JC virus (JCV) load in the cerebrospinal fluid (CSF) is discussed as a parameter for disease progression. To investigate the evolution of viral shedding into the CSF, the JCV DNA concentration was quantified by competitive polymerase chain reaction (PCR) in multiple CSF samples from prior to and during an unsuccessful intrathecal salvage therapy in 2 human immunodeficiency virus—infected patients with biopsy-proven PML. With continuous clinical progression the virus load varied considerably intra- and interindividually, ranging from nondetectable to 1.2 × 108 genome equivalents/10 µL CSF. Whereas an overall increase during progressive disease was confirmed, the virus burden was either constant or fluctuated irregularly during the intermediate stage of disease. This shows a variability of viral shedding during active disease that must be taken into account when the JCV load is measured by quantitative PCR for both the diagnosis of PML and monitoring under investigational treatment.