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An aid in diagnosing progressive multifocal leukoencephalopathy due to JC virus
JC virus (JCV), a member of the genus Polyomavirus, is a small non-enveloped DNA-containing virus. Primary infection occurs in early childhood, with a prevalence of >80%.(1) The virus is latent but can reactivate in immunosuppressed patients, especially those with AIDS.
JCV is recognized as the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system.(2,3) 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.(4) Importantly, the PCR test is specific with no cross-reaction with BK virus, a closely related polyomavirus.
Detection of JC virus (JCV) DNA supports the clinical diagnosis of progressive multifocal leukoencephalopathy due to JCV.
A negative result does not rule out the possibility of JC virus (JCV) infection.
This test is not to be used as a diagnostic tool for Creutzfeldt-Jakob disease.
The reference range in cerebrospinal fluid is "negative" for this assay, although JCV DNA may be detectable in the absence of clinical symptoms in certain patient populations.(5,6) However, this assay is only to be used for patients with appropriate neurological and neuroradiological features of progressive multifocal leukoencephalopathy, and is not indicated for screening asymptomatic patients.
The following data supports the use of this assay for clinical testing.
Twenty-six negative cerebrospinal fluid (CSF) specimens were spiked with JC virus (JCV)-positive control plasmid at the limit of detection (approximately 10 targets/mcL). The 26 spiked specimens were run in a blinded manner with 14 negative (nonspiked) specimens. 100% of the spiked specimens were positive and 100% of the nonspiked specimens were negative.
Analytical Sensitivity/Limit of Detection (LoD):
The lower LoD of this assay is 10 DNA target copies per mcL in CSF.
No PCR signal was obtained from the extracts of 15 viral isolates that may cause similar symptoms or be found in the CSF, including herpes simples virus types 1 and 2, Epstein-Barr virus, cytomegalovirus, human herpesvirus (HHV)-6, HHV-7, HHV-8, enterovirus, mumps, adenovirus, BK virus, and Simian virus 40 (SV40).
Interassay precision was 100% and intraassay precision was 100%.
The reference range in CSF is "negative" for this assay.
This is a qualitative assay and the results are reported as either negative or positive for targeted JCV DNA.
1. Safak M, Khalili K: An overview: human polyomavirus JC virus and its associated disorders. J Neurovirol 2006;9 Suppl 1:3-9
2. Khalili K, White MK: Human demyelinating disease and the polyomavirus JCV. Mult Scler 2006 Apr;12(2):133-142
3. Ahsan N, Shah KV: Polyomaviruses and human diseases. Adv Exp Med Biol 2006;577:1-18
4. Romero JR, Kimberlin DW: Molecular diagnosis of viral infections of the central nervous system. Clin Lab Med 2003 Dec;23(4):843-865
5. Chen Y, Bord E, Tompkins T, et al: Asymptomatic reactivation of JC virus in patients treated with natalizumab. N Engl J Med 2009 Sep 10;361(11):1067-1074
6. Egli A, Infanti L, Dumoulin A, et al: Prevalence of polyomavirus BK and JC infection and replication in 400 healthy donors. J Infect Dis 2009 Mar 15;199(6):837-846