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HelpTest Code HHV6 Human Herpesvirus-6, Molecular Detection, PCR, Plasma
Reporting Name
HHV-6 PCR, PUseful For
As an adjunct in the rapid diagnosis of human herpesvirus-6 infection using plasma specimens
This test should not be used to screen asymptomatic patients.
Method Name
Real-Time Polymerase Chain Reaction (PCR)/DNA Probe Hybridization
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Plasma EDTASpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Lavender top (EDTA)
Submission Container/Tube:
Preferred: Plastic vial
Acceptable: Screw-capped, sterile container
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot plasma into plastic vial.
Specimen Minimum Volume
0.3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma EDTA | Refrigerated (preferred) | 7 days | |
| Frozen | 7 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
Reference Values
Negative
Day(s) Performed
Monday through Saturday
CPT Code Information
87532
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| HHV6 | HHV-6 PCR, P | 29495-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 87532 | HHV-6 PCR, P | 29495-9 |
Clinical Information
Herpesvirus-6 (HHV-6) is a member of the Herpesviridae family. These viruses contain DNA surrounded by a lipid envelope. Among members of this group, this virus is most closely related to cytomegalovirus (CMV) and HHV-7. As with other members of the herpesvirus group (herpes simplex virus [HSV] 1, HSV 2, varicella-zoster virus, CMV, Epstein-Barr virus, HHV-7, HHV-8), HHV-6 may cause primary and reactivated infections subsequent to latent association with cells.(1) Infection with HHV-6 occurs early in childhood. Most adults (80%-90%) have been infected with this virus.
HHV-6 was first linked with exanthem subitum (roseola infantum) in 1998; since then, the virus has been associated with central nervous system disease almost exclusively in patients who are immunocompromised.(1) HHV-6 is commonly detected in patients posttransplantation. Clinical symptoms associated with this viral infection include febrile illness, pneumonitis, hepatitis, encephalitis, and bone marrow suppression. However, the majority of HHV-6 infections are asymptomatic.(2) The incidence of HHV-7 infection and its clinical manifestations posttransplantation are less well characterized.
HHV-6 is designated as variant A (HHV-6A) or variant B (HH6-B) depending on restriction enzyme digestion patterns and its reaction with monoclonal antibodies. Generally, variant B has been associated with exanthem subitum, whereas variant A has been found in many immunosuppressed patients.(3)
Interpretation
A positive result indicates the presence of specific DNA from human herpesvirus-6 (HHV-6) and supports the diagnosis of infection with this virus.
A negative result indicates the absence of detectable DNA from HHV-6 in the specimen, but it does not negate the presence of the virus or active or recent disease.
Cautions
The sensitivity of the assay is very dependent upon the quality of the specimen submitted.
A negative test does not exclude human herpesvirus-6 (HHV-6) virus infection. Therefore, the results obtained should be used in conjunction with clinical findings to make an accurate diagnosis.
This assay detects nucleic acid and, therefore, cannot distinguish between viable and nonviable virus. Test performance depends on viral load in the specimen and may not correlate with cell culture performed on the same specimen.
Method Description
Viral nucleic acid is extracted by the MagNA Pure automated instrument (Roche Applied Science) from clinical specimens. Primers directed to the immediate early gene of human herpesvirus-6 (HHV-6) produce a 195-base pairs amplicon. The LightCycler instrument (Roche Applied Science) amplifies and monitors the development of target nucleic acid sequences after the annealing step during polymerase chain reaction (PCR) cycling. This automated PCR system can rapidly (1 hour) detect amplicon development through stringent air-controlled temperature cycling and 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 light of a different wavelength that can be measured with a signal that is proportional to the amount of specific PCR product. LightCycler hybridization probes are designed for exact homology to HHV-6.(Cockerill FR III, Uhl JR: Applications and challenges of real-time PCR for the clinical microbiology laboratory. In: Reischel U, Wittwer C, Cockerill F. Rapid Cycle Real-Time PCR - Methods and Applications. Springer-Verlag;2002: 3-30)