Effective use of JC virus PCR for diagnosis of progressive multifocal leukoencephalopathy

Area of Science:

• Neurology
• Virology
• Immunology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare, opportunistic demyelinating disease.
• JC virus (JCV) is the causative agent of PML.
• Diagnosis of PML often relies on clinical presentation, imaging, and JCV detection.

Purpose of the Study:

• To evaluate the diagnostic utility of JCV PCR in cerebrospinal fluid (CSF) for suspected PML.
• To identify patient populations most likely to benefit from JCV PCR testing.

Main Methods:

• Retrospective review of 168 patients with suspected PML between 1996 and 2006.
• Analysis of JCV PCR results from CSF samples.
• Correlation with patient immune status (HIV infection, CD4 cell counts) and radiographic findings.

Main Results:

• JCV PCR was positive in HIV-infected patients with low CD4 counts and severely immunocompromised patients with PML-consistent lesions.
• One HIV patient with a very low CD4 count tested positive for JCV PCR despite a normal MRI.
• Testing yielded positive results primarily in high-risk patient groups.

Conclusions:

• JCV PCR testing on CSF is a valuable diagnostic tool for PML.
• Targeting JCV PCR testing to HIV-infected patients with low CD4 counts and severely immunocompromised individuals improves diagnostic yield.
• JCV PCR can detect infection even in the absence of typical radiographic findings.