Human herpesvirus 6

Human herpes virus type 6 (HHV- 6) is a human pathogen herpes virus of the subfamily of the beta herpes viruses. It is the causative agent of the three-day fever ( exanthema subitum, roseola infantum, " Sixth disease" ), a disease ( ie under 2 years ) predominantly occurs in infancy or early infancy. One of the virus involvement in other diseases is discussed, however, is not proven.

Historical

HHV -6 was discovered in 1986 in the laboratory of Robert Gallo at the NIH. The explorers thought they had to do it with a B -cell lymphotropic herpes virus. But soon it turned out that HHV -6 infected CD4-positive T lymphocytes. HHV-6 is therefore adjacent to the human herpes virus type 7, the later discovered only known human herpes virus that infects primarily T lymphocytes (all other human herpes viruses are B-cell lymphotropic ).

Epidemiology and transmission

HHV -6 is a virtually ubiquitous common virus. In adulthood, at least 80 % of the population is seropositive, ie are latently infected with the virus. The infection happens it usually in infancy or early childhood by droplet infection and often clinically inapparent runs, that is, without significant symptoms. Symptomatic infection is usually expressed as a three - day fever.

HHV -6 type A and type B

Of HHV -6, two subtypes are known, A and B. The subtype A have so far been no associated diseases. Human herpes virus type 6B ( HHV -6B ) is the cause of the three-day fever. In immunocompromised patients, such as AIDS or following bone marrow or stem cell transplantation often leads to a strong virus. However, it is unclear especially in the latter two groups of patients, whether this has any real clinical significance. Maybe the virus plays a role in this situation as causing encephalitis, pneumonia, or bone marrow aplasia.

Like all herpesviruses HHV-6 has the ability to " latency " that is a " persistence " in the organism for a long time. Usually can not be completely eliminated by the virus infection. Mostly, however, it does not cause any further problems, but it can revive and multiply again when the immune system is weakened (see above).

Virus detection

The virus detection succeeds serologically usually, that is, by the detection of antibodies against the virus. However, these are not formed until some time after the infection. In infants, antibodies may be present, which can distort the image even by the mother through the placenta transmitted. In the period of acute infection, the viral DNA by polymerase chain reaction (PCR) or by electron microscopy can be detected. In addition to the evidence in the peripheral blood of these succeed in people with an inherited chromosomal integrated HHV-6 infection in each body cell.

Therapy and vaccination

Vaccination against HHV -6 is not yet available. In case of serious complications (eg, encephalitis) antiviral therapy with ganciclovir or foscarnet should be attempted. Larger studies would demonstrate the effectiveness of these antivirals, but there is no date.

HHV -6 as a trigger other diseases

HHV -6 is used as a trigger of the so-called chronic fatigue syndrome ( chronic fatigue syndrome ) are discussed. Also, the virus can cause myocarditis or cardiomyopathy. One of the main symptoms of such a heart viral disease is chronic fatigue syndrome. In addition, the virus is a potential factor in the pathogenesis of multiple sclerosis in the discussion for some time. Unique data that would prove an involvement in these diseases, but there is no date.