Human herpesvirus 6
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.[9]
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.[10] Several studies have found that active infection is more common in CFS patients than healthy controls.[11]
Antivirals[edit | edit source]
There have been no controlled trials of antivirals for HHV-6. Those used clinically are the drugs used for human cytomegalovirus: ganciclovir, valganciclovir, and to a lesser extent acyclovir.
Notable studies[edit | edit source]
- 1994, Prevalence of Human Herpesvirus 6 Variants A and B in Patients with Chronic Fatigue Syndrome
- 2016, Human herpesvirus 6 and 7 are biomarkers for fatigue, which distinguish between physiological fatigue and pathological fatigue[12]
Learn more[edit | edit source]
- HHV-6 Foundation
- 2018, A Common Virus May Play Role in Alzheimer’s Disease, Study Finds by Pam Belluck via NY Times
See also[edit | edit source]
References[edit | edit source]
- ↑ https://www.ncbi.nlm.nih.gov/pubmed/9227865
- ↑ https://www.ncbi.nlm.nih.gov/pubmed/21825120
- ↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC544175/
- ↑ Pietiläinen-Nicklén J, Virtanen JO, Uotila L, Salonen O, Färkkilä M, Koskiniemi M. (2014). HHV-6-positivity in diseases with demyelination. Journal of Clinical Virology, 61 (2):216-9. doi: 10.1016/j.jcv.2014.07.006. Epub 2014 Jul 21. Rerieved from http://www.ncbi.nlm.nih.gov/pubmed/25088617
- ↑ https://www.ncbi.nlm.nih.gov/pubmed/17276367
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/7638210/
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/8936350
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/11781402/
- ↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC544175/
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/9453750
- ↑ https://www.ncbi.nlm.nih.gov/pubmed/17276367
- ↑ 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