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HHV-6: General Information:
Human Herpes Virus 6 (HHV-6) is a β-herpes virus that was first isolated in 1986 from the peripheral blood of 6 patients with a variety of lymphoproliferative disorders, some of which had AIDS.(1)
The virus is highly sero-prevalent and studies have shown that it is present in almost 100% of the general population. It has worldwide distribution and infection generally occurs within the first two years of life, where it causes an illness known as “Roseola Infantum”. Roseola Infantum is also known as Roseola, 6th Disease and Exanthem Subitum. The symptoms of this primary infection may begin with the child experiencing a sudden high fever (39-40oC), that can lead to febrile convulsions due to the sudden rise in temperature. After a few days, the fever subsides and a red rash appears on the child’s body. The rash disappears within twenty four hours.(1,3)
It is estimated that HHV 6 is the single most common cause (10 – 40%) of children presenting to hospitals with a rash.(1,2)
After the primary infection, the virus establishes a latent infection in the individual for life. However re-activation of the virus can occur if the individual becomes immuno-compromised. Re-activation of the virus has been reported to be relatively common after solid organ and stem-cell transplantation. It is estimated that the following percentages of transplants are affected by HHV 6 reactivation.(4)
Percentages of transplant patients affected by HHV-6
reactivation, causing complications(3) |  | Renal: 38 - 55%
Liver: 22 - 54%
Heart/Lung: up to 57% |
These re-activations can cause: (1,4) HHV 6 is also thought to play a role in a number of diseases including as a cofactor in the progression from HIV to AIDS, Multiple Sclerosis, Chronic Fatigue Syndrome and other neurological disorders.(1)
The virus is associated with CMV infection and there is evidence to suggest that reactivation in combination with CMV results in a significantly increased risk of symptomatic disease compared to that from either of the viruses alone. Research is ongoing in these areas. (5,6)
As almost 100% of the population is sero positive for HHV 6, it is important to distinguish latent HHV 6 infections from active infections. PCR will detect HHV 6 viral DNA but it is unable to diagnose active or latent infections. As the virus is so prevalent, serology assays remain the assays of choice to accurately diagnose active infections with a high level of sensitivity.
Chromosomal integration of HHV 6 has also been shown in immuno-compromised patients, where high levels of HHV 6 viral DNA has been reported in blood samples. These high levels may be misinterpreted by PCR as active infections. (7) HHV-6 is rare amongst the herpesviruses in that it exhibits this pnenomenon and reliance on molecular techiniques may confuse diagnosis.
The Biotrin range of HHV assays include high sensitivity and specificity serology assays, both EIA’s and IFA’s that measure the presence of HHV 6 antibodies in fresh/frozen human plasma and serum samples. For additional information on the Biotrin HHV 6 assays, please click on the links below: HHV 6 IgG IFA HHV 6 IgM IFA HHV 6 IgG EIA
Useful links for additional information on HHV 6:
Bibliography - Clark, Duncan A. "Human Herpesvirus 6." Rev. Med. Virol. 10 (2000): 155-173.
- De Bolle, Leen, Lieve Naesens, and Erik De Clercq. "Update on Human Herpesvirus 6 Biology, Clinical Features, and Therapy." Clinical Microbiology Reviews 18 (2005): 217-245.
- "HHV-6 in the Transplant Population." ViraCor 3 (2005): 1-5.
- Lehto, Juho T. et al. "Human Herpesvirus-6 and -7 After Lung and Heart-Lung Transplantation." The Journal of Heart and
Lung Transplantation 26 (2007): 41-47. - Jenkins, Frank J. "Herpesvirus Infections in Organ Transplant Recipients." Clin Diagn Lab Immunol 10 (2003): 1-7.
- Humar, A. "Human Herpesvirus–6 is Associated with Cytomegalovirus Reactivation." The Journal of Infectious Diseases 181 (2000): 1450-1453.
- Ward, Katherine N. "Human Herpesvirus 6 Chromosomal Integration in Immunocompetent." Journal of Clinical Microbiology 44 (2006): 1571-1574.
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