Viruses can affect the monitor

Viruses in the cerebellum probably trigger depression

WÜRZBURG. Purkinje cells are an important part of the human cerebellum - the part of the brain that is primarily responsible for motor learning and the fine control of muscle tension and movements, but which also influences feelings, perception, memory and language.

Scientists around Dr. Bhupesh Prusty from the Institute of Virology and Immunobiology at the University of Würzburg, together with colleagues in the USA, have made a surprising discovery in these nerve cells: In patients with bipolar and severe depressive disorders, they found a high rate of infection with the human herpes virus HHV in Purkinje neurons 6 (Frontiers in Microbiology 2018; online in August).

Viruses affect the nervous and immune systems

"Viruses can disrupt the development of nerve cells and hinder the interaction with the immune system in important stages of development," explains Prusty in a communication from the University of Würzburg. If such an infection occurs in early childhood, it usually passes without a trace.

However, the viruses persist in various organs and tissues, including the CNS and salivary glands, and under certain circumstances become active again after years.

Prusty and his team suggested that human herpes viruses of the type HHV-6A and HHV-6B could play a key role in the development of psychiatric disorders. They therefore scrutinized two of the largest human brain biopsy cohorts from the Stanley Medical Research Institute (USA) and found what they were looking for: "We were able to show an increased rate of active human herpesvirus infections in patients with bipolar and severe depressive disorders, mainly in Purkinje- Detect cells of the human cerebellum, "says Prusty.

No "sleeping" diseases

This is an indication that viruses of the type HHV-6 infect nerve cells and possibly cause cognitive disorders that lead to mood disorders. According to the scientists, this refutes the assumption that viruses which occur frequently in humans and which "slumber" undetected in organs and tissues are never responsible for a disease.

"Studies, like our current one, prove that this thinking is wrong," says Prusty. In line with this, another current study shows that there is a connection between Alzheimer's disease and human herpes viruses.

In a next step, the Würzburg scientists now want to decipher the molecular mechanism by which the herpes viruses cause damage to Purkinje neurons. (eb)