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Test ID: 81107    
JC Virus (JCV) Detection by In Situ Hybridization

Useful For Suggests clinical disorders or settings where the test may be helpful

Confirming a clinical and histopathologic diagnosis of progressive multifocal leukoencephalopathy (PML); especially helpful when only a small piece of biopsy material is available

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

JC virus (JCV) was isolated from brain tissue of a patient with progressive multifocal leukoencephalopathy (PML), a rare, demyelinating, fatal disorder of the central nervous system which occurs on a background of immune deficiency. PML occurs as an infrequent complication of a wide variety of conditions, including: lymphoproliferative disorders such as Hodgkin disease, chronic lymphocytic leukemia, and lymphosarcoma; chronic diseases such as sarcoidosis and tuberculosis, and primary immunodeficiency diseases. PML has also been recognized as a frequent complication of the AIDS. Most cases of PML, not associated with AIDS, occur in middle age or later life, but the disease may occur in an immunocompromised individual of any age and has been recognized in young children with immunodeficiency diseases.


JCV also infects humans in childhood and is present in most of the world's population. It is the etiologic agent of PML. Clinically, signs and symptoms of asymmetric multifocal brain disease without signs of increased intracranial pressure in a person who is immunocompromised would suggest the diagnosis of PML. Computed tomographic scan or magnetic resonance imaging of the brain is effective in establishing the diagnosis of PML in a noninvasive manner. The unique histopathologic features of PML can be identified by light microscopy of a brain biopsy specimen. JCV can be cultivated in cell cultures, and serologic assays have been developed, but nucleic acid detection methods are much more sensitive and rapid for making the laboratory diagnosis of PML using brain tissue.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

This test, when not accompanied by a pathology consultation request, will be answered as either positive or negative.

If additional interpretation/analysis is needed, please request 70012 / Pathology Consultation along with this test.

Interpretation Provides information to assist in interpretation of the test results

"Positive for Polyomavirus (JC Virus)" indicates the presence of infection with JCV.


"Negative for Polyomavirus (JC Virus)" indicates the absence of cells infected with JCV.


A negative result is normal.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Prolonged formalin fixation may cause false-negative results. A few weeks appears to be the maximum time of fixation.


Submitted specimens will be screened by a pathologist to determine the acceptability of the specimen for the test.


Slides must be specially prepared, therefore, a paraffin-embedded, formalin-fixed tissue must also be submitted.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Aksamit AJ, Mourrain P, Sever JL, Major EO: Progressive multifocal leukoencephalopathy: investigation of three cases using in situ hybridization with JC virus biotinylated DNA probe. Ann Neurol 1985;18:490-496

2. Telenti A, Aksamit AJ Jr, Proper J, Smith TF: Detection of JC virus DNA by polymerase chain reaction in patients with progressive multifocal leukoencephalopathy. J Infect Dis 1990;162:858-861

3. Aksamit AJ Jr: Nonradioactive in situ hybridization in progressive multifocal leukoencephalopathy. Mayo Clin Proc 1993;68:899-910