Diagnostic Test Directory

Virology Laboratory

Human Herpes Virus-6 (HHV-6) PCR (Quantitative) - blood specimen

  • LIS Mnemonic: HHV6PCR


    Lavendar (EDTA)

    Volume Required

    4-7 ml whole blood

    Minimum Required

    4 ml whole blood


    Transport blood in a timely fashion (preferably within 8 hours of collection) at room temperature to the Clinical Virology Laboratory.




    Whole blood in an EDTA-anticoagulated tube is the preferred specimen source. Thoroughly mix the blood by gently inverting the collection tube 6-12 times before sending to the laboratory. Other acceptable specimens include body fluids, tissue submitted in viral transport medium, bone marrow in EDTA, and CSF.

    Unacceptable conditions

    Clotted specimens

Days Performed



Same day

Reflex Testing

When monitoring the blood of immunocompromised patients for HHV-6 over time, a quantitative PCR assay will be automatically performed on all patients whose blood has been previously positive for HHV-6 by qualitative and/or quantitative PCR testing.




Amplification and quantification of HHV-6 DNA U65-U66 gene region using TaqMan real-time PCR technology. The test is performed pursuant to an agreement with Roche Molecular Systems, Inc.

Disease Information


Human herpes virus type-6 (HHV-6) is the cause of roseola infantum, an illness characterized by an erythematous maculopapular rash with high fever in 20% of children. The disease is also called exanthum subitum and Sixth disease. Other illnesses include undifferentiated febrile illness without rash or localized signs, febrile seizures (common with roseola), infectious mononucleosis-like syndromes, hepatitis, and neurologic syndromes (e.g., encephalitis). Transplant recipients may have fever, hepatitis, leukopenia, delayed engraftment, neurologic disease, skin rashes, pneumonia, and bone marrow suppression. The virus may contribute to disease progression with HIV-1 and exacerbate disease with other viruses. The diagnosis of HHV-6 infection is increasingly being made by PCR, and HHV-6 DNA has been detected in specimens from solid-organ and bone marrow transplant recipients; children with roseola, acute febrile illnesses, encephalitis and febrile seizures, and other manifestations of primary infection; and AIDS patients. Quantitative PCR assays should be used in immunocompromised patients to associate infection with disease, predict and monitor disease progression, assess efficacy of antiviral therapy, and to facilitate our understanding of the pathogenesis of HHV-6. In these patients, viremia is considered to be the best predictor of disease, and quantitative measures of HHV-6 DNA in blood is useful for the continued surveillance and management of transplant patients.


If positive, quantity of human herpesvirus-6 DNA is reported in copies/ml and log10 values. Dynamic range of the assay is 134 copies/ml to 2.17 milli

Reference Values

Negative or quantity of human herpesvirus-6 DNA is less than the lower limit of detection

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