Human herpesvirus 6

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Human herpesvirus 6 (HHV-6) is a set of two closely related herpesviruses, HHV6-A and HHV6-B. Infection is extremely common and usually occurs at an early age. 64-83% of infants are infected by age 13 months.[1] HHV-6 has an affinity for leukocytes and nervous tissue, especially the olfactory bulb tissues[2], from which it is thought to disseminate to other parts of the brain. After infection the virus remains latent but can reactivate asymptomatically even in healthy individuals.

HHV-6 has been found to activate Epstein-Barr virus from latency. Conversely, the presence of EBV renders B cells more susceptible to HHV-6 infection.[3]

In human disease[edit | edit source]

HHV-6 has been implicated as a contributing factor to a number of neurological diseases including multiple sclerosis[4], chronic fatigue syndrome[5] and epilepsy, as well as fibromyalgia and AIDS.

Multiple sclerosis[edit | edit source]

HHV-6 has been found in the oligodendrocytes of plaques in MS patients but not in healthy tissue.[6]

Antivirals may have some therapeutic benefit. A randomized, placebo-controlled double-blind study found that acyclovir reduced the exacerbation rate in relapsing-remitting MS patients.[7]. Valacyclovir reduced new lesions in patients with high disease activity.[8]

Cancer[edit | edit source]

Like Epstein-Barr virus, HHV-6 is associated with lymphomas and carcinomas.[3]

Chronic fatigue syndrome[edit | edit source]

One study found a higher prevalence of past HHV-6 infection in chronic fatigue syndrome patients but with a low viral load that did not suggest reactivation.[9] Several studies have found that active infection is more common in CFS patients than healthy controls.[5]

Antivirals[edit | edit source]

There is no drug approved for treating HHV-6.[10] Those used clinically are the drugs used for human cytomegalovirus: ganciclovir (Cytovene IV), cidofovir (Vistide IV), and foscarnet (Foscavir IV).[10][11]

Notable studies[edit | edit source]

Learn more[edit | edit source]

See also[edit | edit source]

References[edit | edit source]

  1. Braun, D. K.; Dominguez, G.; Pellett, P. E. (Jul 1997). "Human herpesvirus 6". Clinical Microbiology Reviews. 10 (3): 521–567. ISSN 0893-8512. PMID 9227865. 
  2. Harberts, Erin; Yao, Karen; Wohler, Jillian E.; Maric, Dragan; Ohayon, Joan; Henkin, Robert; Jacobson, Steven (Aug 16, 2011). "Human herpesvirus-6 entry into the central nervous system through the olfactory pathway". Proceedings of the National Academy of Sciences of the United States of America. 108 (33): 13734–13739. doi:10.1073/pnas.1105143108. ISSN 1091-6490. PMC 3158203Freely accessible. PMID 21825120. 
  3. 3.03.1 De Bolle, Leen; Naesens, Lieve; De Clercq, Erik (Jan 2005). "Update on Human Herpesvirus 6 Biology, Clinical Features, and Therapy". Clinical Microbiology Reviews. 18 (1): 217–245. doi:10.1128/CMR.18.1.217-245.2005. ISSN 0893-8512. PMID 15653828. 
  4. Pietiläinen-Nicklén, Jenna; Virtanen, Jussi O.; Uotila, Lasse; Salonen, Oili; Färkkilä, Markus; Koskiniemi, Marjaleena (Oct 2014). "HHV-6-positivity in diseases with demyelination". Journal of Clinical Virology. 61 (2): 216–219. doi:10.1016/j.jcv.2014.07.006. ISSN 1873-5967. PMID 25088617. 
  5. 5.05.1 Komaroff, Anthony L. (Dec 2006). "Is human herpesvirus-6 a trigger for chronic fatigue syndrome?". Journal of Clinical Virology: The Official Publication of the Pan American Society for Clinical Virology. 37 Suppl 1: S39–46. doi:10.1016/S1386-6532(06)70010-5. ISSN 1386-6532. PMID 17276367. 
  6. Challoner, P. B.; Smith, K. T.; Parker, J. D.; MacLeod, D. L.; Coulter, S. N.; Rose, T. M.; Schultz, E. R.; Bennett, J. L.; Garber, R. L. (Aug 1, 1995). "Plaque-associated expression of human herpesvirus 6 in multiple sclerosis". Proceedings of the National Academy of Sciences of the United States of America. 92 (16): 7440–7444. doi:10.1073/pnas.92.16.7440. ISSN 0027-8424. PMID 7638210. 
  7. Lycke, J.; Svennerholm, B.; Hjelmquist, E.; Frisén, L.; Badr, G.; Andersson, M.; Vahlne, A.; Andersen, O. (Mar 1996). "Acyclovir treatment of relapsing-remitting multiple sclerosis. A randomized, placebo-controlled, double-blind study". Journal of Neurology. 243 (3): 214–224. doi:10.1007/bf00868517. ISSN 0340-5354. PMID 8936350. 
  8. Bech, E.; Lycke, J.; Gadeberg, P.; Hansen, H. J.; Malmeström, C.; Andersen, O.; Christensen, T.; Ekholm, S.; Haahr, S. (Jan 8, 2002). "A randomized, double-blind, placebo-controlled MRI study of anti-herpes virus therapy in MS". Neurology. 58 (1): 31–36. doi:10.1212/wnl.58.1.31. ISSN 0028-3878. PMID 11781402. 
  9. Cuende, J. I.; Civeira, P.; Diez, N.; Prieto, J. (Sep 1997). "High prevalence without reactivation of herpes virus 6 in subjects with chronic fatigue syndrome". Anales De Medicina Interna. 14 (9): 441–444. ISSN 0212-7199. PMID 9453750. 
  10. 10.010.1 "HHV-6 Treatment". HHV-6 Foundation. Retrieved Mar 1, 2020. 
  11. Prichard, Mark N.; Whitley, Richard J. (Dec 2014). "The Development of New Therapies for Human Herpesvirus 6". Current opinion in virology. 0: 148–153. doi:10.1016/j.coviro.2014.09.019. ISSN 1879-6257. PMC 4267975Freely accessible. PMID 25462447. 
  12. Aoki, R; Kobayashi, N; Suzuki, G; Kuratsune, H; Shimada, K; Oka, N; Takahashi, M; Yamadera, W; Iwashita, M; Tokuno, S; Nibuya, M; Tanichi, M; Mukai, Y; Mitani, K; Kondo, K; Ito, H; Nakayama, K (2016). "Human herpesvirus 6 and 7 are biomarkers for fatigue, which distinguish between physiological fatigue and pathological fatigue". Biochemical and Biophysical Research Communications. 478 (1): 424-30. doi:10.1016/j.bbrc.2016.07.010. PMID 27396623. 
  13. Schreiner, Philipp; Harrer, Thomas; Scheibenbogen, Carmen; Lamer, Stephanie; Schlosser, Andreas; Naviaux, Robert K.; Prusty, Bhupesh K. (Apr 1, 2020). "Human Herpesvirus-6 Reactivation, Mitochondrial Fragmentation, and the Coordination of Antiviral and Metabolic Phenotypes in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome". ImmunoHorizons. 4 (4): 201–215. doi:10.4049/immunohorizons.2000006. ISSN 2573-7732. PMID 32327453. 

double blinded trial - A clinical trial is double blinded if neither the participants nor the researchers know which treatment group they are allocated to until after the results are interpreted. This reduces bias. (Learn more: www.nottingham.ac.uk)

chronic fatigue syndrome (CFS) - A fatigue-based illness. The term CFS was invented invented by the U.S. Centers for Disease Control as an replacement for myalgic encephalomyelitis (ME). Some view CFS as a neurological disease, others use the term for any unexplained long-term fatigue. Sometimes used as a the term as a synonym of myalgic encephalomyelitis, despite the different diagnostic criteria.

mitochondria - Important parts of the biological cell, with each mitochondrion encased within a mitochondrial membrane. Mitochondria are best known for their role in energy production, earning them the nickname "the powerhouse of the cell". Mitochondria also participate in the detection of threats and the response to these threats. One of the responses to threats orchestrated by mitochondria is apoptosis, a cell suicide program used by cells when the threat can not be eliminated.

myalgic encephalomyelitis (ME) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

chronic fatigue syndrome (CFS) - A fatigue-based illness. The term CFS was invented invented by the U.S. Centers for Disease Control as an replacement for myalgic encephalomyelitis (ME). Some view CFS as a neurological disease, others use the term for any unexplained long-term fatigue. Sometimes used as a the term as a synonym of myalgic encephalomyelitis, despite the different diagnostic criteria.

The information provided at this site is not intended to diagnose or treat any illness.
From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history.