Chickenpox is an interesting example. The disease provokes a very itchy purulent ulcer. It is triggered by the varicella-zoster virus, one of the most well-known herpes viruses that infects humans and makes people sick. The virus is widespread throughout the world and is mainly known as a children’s disease. The majority of infected children recover, most leaving only scars. However, the virus also stays in the body.
The varicella-zoster variant of the herpes virus usually attacks the body’s nerve cells called ganglia. This virus can “sleep” for decades in the body and suddenly can be active again in the form of herpes zoster or shingles. In addition, the herpes simplex virus type 1 and 2 variants are also widespread throughout the world. The infection causes inflammation of the lips and herpes on the genitals. Or also cytomegalovirus which triggers severe complications and organ damage in people who suffer from a weakened immune system disease.
Epstein-Barr virus and Kaposi-sarcoma, which are related herpes viruses, can trigger the appearance of tumors. Or the human herpes virus types 6 and 7 which are also widespread and trigger the “three-day fever” disease in children.
Live latent in the body
“The most important thing about the herpes virus is that after the first infection, the virus will remain in the body latent,” said Lars Dölken, a virologist at the University of Würzburg. With that, Dölken emphasized the most important similarities of the virus families.
He and other research colleagues want to better understand the mechanism behind the sudden re-emergence of the pathogen. The research team mainly focused on the human herpes virus 6a or HHV6A.
The research results of the research team have been published in the scientific journal Nature. They discovered an unknown cellular mechanism, which is like waking the virus from its slumber.
Between the active phase and the sleep phase
Those who are infected with the herpes virus for the first time are mostly unaware of this. Problems usually arise when the virus reacts from a dormant phase in the body. Viruses often “wake up” and attack the body, taking advantage of the phase when the immune system is weak, as it is fighting other diseases. It could be just the common cold or a more serious illness. Especially those who are most vulnerable are people living with HIV or also people who have received organ transplants, and their immune systems have been weakened.
The HHV-6A virus fuses with the human cell genome and stays there in a latent phase, until there is a good opportunity to attack and reproduce. A certain micro-RNA plays a role in the reactivation mechanism of the virus.
“Almost all Herpes viruses form Micro-RNA, because this is very important for the virus. But there is no example of a single herpes virus species that proves Micro-RNA has a fundamental role. If we deactivate this viral Micro-RNA, then the virus will also die “, says virologist Dölken.
A viral micro-RNA as the main regulator
Micro-RNA is very different from mRNA, in that it is not responsible for carrying a specific protein blueprint. They include non-coding RNA. Furthermore, these Micro-RNAs attack certain metabolisms of human Micro-RNAs and prevent their development.
As a result, the production of so-called Interferon type-I will be disrupted. It is the messenger element, by which the cell reports the presence of the virus to the immune system. “However, it is certain that this is not the only mechanism that is sabotaged,” says virologist Dölken. The research they are doing is like scratching the surface.
The viral micro-RNA allows the herpes virus to evade the ambush of the immune system. Or more precisely B cells and T cells that eliminate infected human cells. “These cells recognize proteins foreign to the human body, for example from a virus.”
“The herpes virus with the help of RNA is able to reprogram the host cell and abuse it for the benefit of the virus. Thus, B cells and T cells, which are the immune system’s memory for foreign proteins, are no longer able to recognize that the cells have been infected,” said the virologist from The University of Würzburg it.
From COVID-19 to herpes to Long-COVID?
The discovery of a viral micro-RNA that plays a key role, such as the “master regulator” as Dölken calls it, made it impossible for the research team to carry out tests in cell culture to prevent reactivation of the herpes virus.
However, the knowledge gleaned from various further studies, may in the future work the opposite, namely to help reactivation of latent viral cells in the body, which can be recognized by the immune system and eliminated immediately. Dölken says; Before performing an organ transplant, it is best to inactivate cells infected with the herpes virus.
The research of the virologist from Würzburg can also contribute to the solution of another problem, namely Long-COVID. Because the herpes virus so often self-reactivates and attacks a weakened immune system, scientists suspect that the virus is involved in the various symptoms of Long-Covid disease.
“One of the strongest allegations is that due to corona infection, reactivation of the herpes virus is triggered, and causes secondary damage,” concluded Dölken. Until now, researchers are still asking more questions than getting answers. However, at least there are several main suspects and one of them is the herpes virus HHV6.