JC Polyomavirus Infection: A Narrative Review.

Progressive multifocal leukoencephalopathy (PML) is a devastating and often fatal central nervous system infection caused by John Cunningham polyomavirus virus (JCPyV). PML results from JCPyV reactivation in the setting of impaired cellular immunity in patients with HIV, organ transplantation, severe inflammatory disease, and an increasing number of modern treatments for cancer and autoimmune diseases. The presence of clinical and imaging manifestations consistent with the diagnosis coupled with the demonstration of JCPyV by PCR in cerebrospinal fluid (CSF) are considered diagnostic. Since there are no effective antiviral treatments available, restoring immune function is a key component in PML treatment. Novel immunotherapeutic approaches can ameliorate PML. Immunotherapeutic interventions, such as use of checkpoint inhibitors and viral specific T-cell, have shown promising results, but additional data are needed. In this review, we summarize the available data on risk factors for JCPyV neurological syndrome, clinical, laboratory, and radiological features, and propose an algorithm for management.