Instruct: Given a question, retrieve passages that can help answer the question.
Query: Is there a cure for human herpesvirus 6?
There are no pharmaceuticals approved specifically for treating HHV-6 infection, although the usage of Cytomegalovirus treatments (valganciclovir, ganciclovir,[88] cidofovir, and foscarnet) have shown some success.[7] These drugs are given with the intent of inhibiting proper DNA polymerization by competing with deoxy triphosphate nucleotides[88] or specifically inactivating viral DNA polymerases.[2]
Human herpesvirus 6 (HHV-6) is the common collective name for human herpesvirus 6A (HHV-6A) and human herpesvirus 6B (HHV-6B). These closely related viruses are two of the nine herpesviruses known to have humans as their primary host.[1]
The salivary glands have been described as an in vivo reservoir for HHV-6 infection.[23]
Subfamily Alphaherpesvirinae Genus Simplexvirus Ateline herpesvirus 1, spider monkey herpesvirus. Bovine herpesvirus 2 causes bovine mammillitis and pseudo-lumpyskin disease. Cercopithecine herpesvirus 1, also known as Herpes B virus, causes a herpes simplex-like disease in macaques, usually fatal if symptomatic and untreated in humans. Fruit bat alphaherpesvirus 1 Leporid herpesvirus 4 Macacine herpesvirus 1 Macropodid herpesvirus 2 Papiine herpesvirus 2 Genus Varicellovirus Bovine herpesvirus 1 causes infectious bovine rhinotracheitis, vaginitis, balanoposthitis, and abortion in cattle. Bovine herpesvirus 5 causes encephalitis in cattle. Bubaline herpesvirus 1 Caprine herpesvirus 1 causes conjunctivitis and respiratory disease in goats. Canine herpesvirus 1 causes a severe hemorrhagic disease in puppies. Cercopithecine herpesvirus 9 Cervid herpesvirus 1 Cervid herpesvirus 2 Elk herpesvirus 1 Equine herpesvirus 1 causes respiratory disease, neurological disease/paralysis, and spontaneous abortion in horses. Equine herpesvirus 3 causes coital exanthema in horses. Equine herpesvirus 4 causes rhinopneumonitis in horses. Equine herpesvirus 8 Equine herpesvirus 9 Feline herpesvirus 1 causes feline viral rhinotracheitis and keratitis in cats. Suid herpesvirus 1 causes Aujeszky's disease, also called pseudorabies. Genus Mardivirus Anatid herpesvirus 1 Columbiform herpesvirus 1 Gallid herpesvirus 2 causes Marek's disease. Gallid herpesvirus 3 (GaHV-3 or MDV-2) Meleagrid herpesvirus 1 (HVT) Peacock herpesvirus 1 Genus Iltovirus Gallid herpesvirus 1 causes infectious laryngotracheitis in birds. Psittacid herpesvirus 1 causes Pacheco's disease in birds.
HHV-6 has also been demonstrated to transactivate Epstein–Barr virus.[31]
Roseola is caused by two human herpesviruses, "human herpesvirus 6" (HHV-6) and "human herpesvirus 7" (HHV-7), which are sometimes referred to collectively as Roseolovirus. There are two variants of HHV-6 (HHV-6a and HHV-6b) and studies in the US, Europe, Dubai and Japan have shown that exanthema subitum is caused by HHV-6b. This form of HHV-6 infects over 90% of infants by age 2.
Finding a treatment can be difficult when HHV-6 reactivation occurs following transplant surgery because transplant medications include immunosuppressants.[89]
Primary infection in adults tend to be more severe.[13]
When an extracellular HHV-6 virion comes across human cells, it encounters the human receptor protein cluster of differentiation 46 (CD46), which plays a role in regulating the complement system. The CD46 protein possesses a single variable region, as a result of alternative splicing. As such, at least fourteen isoforms of CD46 exist, all of which bind HHV-6a.[28]
Murid herpesvirus 4 (MuHV 4) is a virus in the genus Rhadinovirus. It is a member of the subfamily Gammaherpesvirinae in the family Herpesviridae. MuHV 4 infects mice via the nasal passages and causes an acute infectious mononucleosis-like syndrome with elevated levels of leukocytes, and shifts in the relative proportion of lymphocytes along with the appearance of atypical mononuclear cells. Murid herpesvirus 4 currently serves as a model for study of human gamma-herpesvirus pathogenesis.
Human herpesvirus 6 lives primarily on humans and, while variants of the virus can cause mild to fatal illnesses, can live commensally on its host.[13] It has been demonstrated that HHV-6 fosters the progression of HIV-1 upon coinfection in T cells.[37] HHV-6 upregulates the expression of the primary HIV receptor CD4, thus expanding the range of HIV susceptible cells. Several studies also have shown that HHV-6 infection increases production of inflammatory cytokines that enhance in vitro expression of HIV-1, such as TNF-alpha,[38] IL-1 beta, and IL-8.[39] A more recent in vivo study shows HHV-6A coinfection to dramatically accelerate the progression from HIV to AIDS in pigtailed macaques.[40]
The role of HHV-6 during pregnancy leading to inflammation in the amniotic cavity has been studied.[77]
Several similar studies followed. A study from October 2014 supported the role of long-term HHV-6 infection with demyelination in progressive neurological diseases.[62]
Multiple sclerosis– direct cell damage and altered cytokines
However, one group of researchers ultimately concluded that HHV-6 may not be involved in MTLE related to Mesial Temporal Sclerosis.[86]
Homologous recombination is the proposed mechanism whereby the DNA virus "human herpesvirus-6" integrates into human telomeres.
In viruses, like Saimiriine herpesvirus 2 ("Herpesvirus saimiri") and Human herpesvirus 8 (HHV-8/Kaposi's sarcoma-associated herpesvirus) cyclin D homologues have acquired new functions in order to manipulate the host cell’s metabolism to the viruses’ benefit.
Viral cyclin D binds human Cdk6 and inhibits Rb by phosphorylating it, resulting in free transcription factors which result in protein transcription that promotes passage through G1 phase of the cell cycle. Other than Rb, viral cyclin D-Cdk6 complex also targets p27, a Cdk inhibitor of cyclin E and A. 
In addition, viral cyclin D-Cdk6 is resistant to Cdk inhibitors, such as p21 and p16 which in human cells inhibits Cdk4 by preventing it from forming an active complex with cyclin D.
A variety of tests are used in the detection HHV-6, some of which do not differentiate the two species.[7]
Examination of a series of tonsils with Western blotting gave a 100% detection rate for HHV-6.[45]
Researchers[30] have shown that T cells are highly infectable by HHV-6.
Caretta caretta herpesvirus Chelonid herpesvirus 1 Chelonid herpesvirus 2 Chelonid herpesvirus 3 Chelonid herpesvirus 4 Chelonia mydas herpesvirus Coober herpesvirus Emydid herpesvirus 1 Emydid herpesvirus 2 Fibropapilloma associated herpes virus Gerrhosaurid herpesvirus 1 Gerrhosaurid herpesvirus 2 Gerrhosaurid herpesvirus 3 Glyptemis herpesvirus 1 Glyptemys herpesvirus 2 Iguanid herpesvirus 1 Iguanid herpesvirus 2 Loggerhead orocutaneous herpesvirus Lung-eye-trachea associated herpesvirus Pelomedusid herpesvirus 1 Red eared slider herpes virus Terrapene herpesvirus 1 Terrapene herpesvirus 2 Testudinid herpesvirus 1 Testudinid herpesvirus 2 Testudinid herpesvirus 3 Testudinid herpesvirus 4 Varanid herpesvirus 1 Subfamily Betaherpesvirinae Genus Proboscivirus Porcine herpesvirus 2 causes inclusion body rhinitis in swine. Subfamily Gammaherpesvirinae Phascolarctid gammaherpesvirus 1 Vombatid gammaherpesvirus 1 Genus Macavirus Genus Percavirus Genus Rhadinovirus Alcelaphine herpesvirus 1 causes bovine malignant catarrhal fever. Alcelaphine herpesvirus 2 causes an antelope and hartebeest version of MCF Ateline herpesvirus 2 Bovine herpesvirus 4 Cercopithecine herpesvirus 17 Equine herpesvirus 2 causes equine cytomegalovirus infection. Equine herpesvirus 5[29] Equine herpesvirus 7 Japanese macaque rhadinovirus[30] Leporid herpesvirus 1 Murid herpesvirus 4 Also known as Murine gammaherpesvirus-68 (MHV-68)
During the progression of the DRESS syndrome certain viruses which previously infected an individual and then became latent are reactivated and proliferate. Viruses known to do so include certain members of the Herpesviridae family of Herpes viruses viz., Epstein-Barr virus, human herpesvirus 6, human herpesvirus 7, and cytomegalovirus. Individuals suffering the DRESS syndrome may exhibit sequential reactivation of these four virus, typically in the order just given. Reactivation of these viruses is associated with sequential flare-ups in symptoms, a prolonged course, and increased disease severity which includes significant organ involvement and the development of certain autoimmune diseases viz., systemic lupus erythematosus, autoimmune thyroiditis, and type 1 diabetes mellitus. While these viral reactivations, particularly of human herpes virus 6, have been suggested to be an important factor in the pathogenesis of the DRESS syndrome, studies to date have not clearly determined if they are a cause or merely a consequence of T cell-mediated tissue injury. Rare case reports have associated the SJS/TEN spectrum of SCARs with reactivation of human herpesvirus 6; reactivation of cytomegalovirus has also been proposed to be associated with AGEP although a large study failed to observe the latter association. In all cases, the relationships of viral reactivation to the development and severity of any SCARs disorder is uncertain and requires further study.
Several species of "Cytomegalovirus" have been identified and classified for different mammals. The most studied is "Human cytomegalovirus" (HCMV), which is also known as "Human herpesvirus 5" (HHV-5). Other primate CMV species include "Chimpanzee cytomegalovirus" (CCMV) that infects chimpanzees and orangutans, and "Simian cytomegalovirus" (SCCMV) and "Rhesus cytomegalovirus" (RhCMV) that infect macaques; CCMV is known as both "Panine herpesvirus 2" (PaHV-2) and "Pongine herpesvirus-4" (PoHV-4). SCCMV is called "Cercopithecine herpesvirus-5" (CeHV-5) and RhCMV, "Cercopithecine herpesvirus 8" (CeHV-8). A further two viruses found in the night monkey are tentatively placed in the genus "Cytomegalovirus", and are called "Herpesvirus aotus 1" and "Herpesvirus aotus 3". Rodents also have viruses previously called cytomegaloviruses that are now reclassified under the genus "Muromegalovirus"; this genus contains "Mouse cytomegalovirus" (MCMV) is also known as "Murid herpesvirus 1" (MuHV-1) and the closely related "Murid herpesvirus 2" (MuHV-2) that is found in rats.
Family: Herpesviridae Subfamily: Alphaherpesvirinae Genus: Iltovirus Gallid herpesvirus 1 Psittacid herpesvirus 1 Genus: Mardivirus Anatid herpesvirus 1 Columbid herpesvirus 1 Gallid herpesvirus 2 Gallid herpesvirus 3 Meleagrid herpesvirus 1 Genus: Scutavirus Chelonid herpesvirus 5 Genus: Simplexvirus Ateline herpesvirus 1 Bovine herpesvirus 2 Cercopithecine herpesvirus 2 Human herpesvirus 1 Human herpesvirus 2 Leporid herpesvirus 4 Macacine herpesvirus 1 Macropodid herpesvirus 1 Macropodid herpesvirus 2 Papiine herpesvirus 2 Saimiriine herpesvirus 1 Genus: Unassigned Chelonid herpesvirus 6 Genus: Varicellovirus Bovine herpesvirus 1 Bovine herpesvirus 5 Bubaline herpesvirus 1 Canid herpesvirus 1 Caprine herpesvirus 1 Cercopithecine herpesvirus 9 Cervid herpesvirus 1 Cervid herpesvirus 2 Equid herpesvirus 1 Equid herpesvirus 3 Equid herpesvirus 4 Equid herpesvirus 8 Equid herpesvirus 9 Felid herpesvirus 1 Human herpesvirus 3 Phocid herpesvirus 1 Suid herpesvirus 1 Sub-Family: Betaherpesvirinae Genus: Cytomegalovirus Aotine herpesvirus 1 Cebine herpesvirus 1 Cercopithecine herpesvirus 5 Human herpesvirus 5 Macacine herpesvirus 3 Panine herpesvirus 2 Papiine herpesvirus 3 Saimiriine herpesvirus 4 Genus: Muromegalovirus Murid herpesvirus 1 Murid herpesvirus 2 Murid herpesvirus 8 Genus: Proboscivirus Elephantid herpesvirus 1 Genus: Roseolovirus Human herpesvirus 7 Human herpesvirus 6A Human herpesvirus 6B Genus: Unassigned Caviid herpesvirus 2 Suid herpesvirus 2 Tupaiid herpesvirus 1 Sub-Family: Gammaherpesvirinae Genus: Lymphocryptovirus Callitrichine herpesvirus 3 Cercopithecine herpesvirus 14 Gorilline herpesvirus 1 Human herpesvirus 4 Macacine herpesvirus 4 Panine herpesvirus 1 Papiine herpesvirus 1 Pongine herpesvirus 2 Genus: Macavirus Alcelaphine herpesvirus 1 Alcelaphine herpesvirus 2 Bovine herpesvirus 6 Caprine herpesvirus 2 Hippotragine herpesvirus 1 Ovine herpesvirus 2 Suid herpesvirus 3 Suid herpesvirus 4 Suid herpesvirus 5 Genus: Percavirus Equid herpesvirus 2 Equid herpesvirus 5 Mustelid herpesvirus 1 Genus: Rhadinovirus Ateline herpesvirus 2 Ateline herpesvirus 3 Bovine herpesvirus 4 Cricetid herpesvirus 2 Human herpesvirus 8 Macacine herpesvirus 5 Murid herpesvirus 4 Murid herpesvirus 7 Saimiriine herpesvirus 2 Genus: Unassigned Equid herpesvirus 7 Phocid herpesvirus 2 Saguinine herpesvirus 1
Human herpesvirus 7 (HHV-7) is one of nine known members of the Herpesviridae family that infects humans. HHV-7 is a member of Betaherpesviridae, a subfamily of the Herpesviridae that also includes HHV-6 and "cytomegalovirus" (HHV-5 or HCMV). HHV-7 often acts together with HHV-6, and the viruses together are sometimes referred to by their genus, "Roseolovirus". HHV-7 was first isolated in 1990 from CD4+ T cells taken from peripheral blood lymphocytes.