Specimen:

CSF

Collection Medium:

Minimum:

Spinal Fluid (For Detection of JC Virus Only)
1.0 mL of spinal fluid.

Analytic Time:

1 week

Reference Range:

Negative

Positive results will be reported as JC virus DNA detected.

Interpretive Data:

Detection of JCV DNA supports the clinical diagnosis of PML due to JCV.

The assay detects >10 genomic equivalents of the virus.

Comments:

Maintain sterility.

JC virus (JCV), a member of the genus Polyomavirus, is a small 
nonenveloped DNA-containing virus. Primary infection occurs in early 
childhood, with a prevalence of >80%.(1) The virus is latent but can be 
reactivated in immunosuppressed patients, especiallythose with AIDS.

JCV is recognized as the etiologic agent of progressive multifocal 
leukoencephalopathy (PML), a fatal demyelinating disease of the central 
nervous system.(2-4) Histologic examination of brain biopsy tissue may 
reveal characteristic pathologic changes localized mainly in 
oligodendrocytes and astrocytes. Detection of JCV DNA by PCR (target 
gene, large T antigen) in the cerebrospinal fluid specimens of patients 
with suspected PML infection has replaced the need for biopsy tissue 
for laboratory diagnosis.(5) This molecular amplification technology 
provides a faster, easier, and more sensitive test for diagnosing of 
JCV infection compared with brain biopsy pathology. Importantly, the 
PCR test is specific with no cross-reaction with BK virus (BKV), a 
closely related polyomavirus.

A negative result does not rule out the possibility of JCV infection.

This test is not to be used as a diagnostic tool for Creutzfeldt-Jakob 
disease (CJD).

Methodology:

Real-Time Polymerase Chain Reaction (PCR)/DNA Probe
Hybridization

Viral nucleic acid is extracted from the specimen using the MagNA Pure 
automated instrument (Roche Applied Science). Primers are directed to 
the large T antigen gene, which is a conserved sequence specific for 
JCV. This assay detects only JCV; it does not detect BK Virus or SV 40 
(other polyomaviruses). The LightCycler instrument (Roche Applied 
Science) amplifies and monitors the development of target nucleic acid 
sequences after the annealing step during PCR cycling. This automated 
PCR system can rapidly detect amplicon development through stringent 
air-controlled temperature cycling in capillary cuvettes. The detection 
of amplified products is based on the fluorescence resonance energy 
transfer (FRET) principle. For FRET product detection, a hybridization 
probe with a donor fluorophore, fluorescein, on the 3'-end is excited 
by an external light source and emits light that is absorbed by a 
second hybridization probe with an acceptor fluorophore, LC-Red 640, at 
the 5'-end. The acceptor fluorophore then emits a light of a different 
wavelength that can be measured with a signal that is proportional to 
the amount of specific PCR product.

CPT Code:

87798