TBE Study Uncovers Virus “Road Map” in the Brain

A new study conducted at Umeå University in Sweden and published in Nature Communications has uncovered a critical piece of information about the tick-borne encephalitis (TBE) virus. The researchers discovered that the virus infects different types of neuronal cells in various areas of the brain, depending on whether the affected person’s immune system is activated or not. This new understanding is an important step towards developing effective therapies and preventive measures against the disease. 

The researchers utilized multimodal imaging-transcriptomics to determine the location of viruses in the brains of mice in three dimensions, allowing the team to observe which specific parts of the brain have been infected with TBE virus. This novel method is based on information from image analyses that were combined with studies of gene expression in different cell types. The result can be seen as a virus “road map” in the brain.

The researchers found that the viral spread with and without an innate immune response was very different. The virus infected different regions of the brain depending on the innate immune system of the mouse.

When the researchers zoomed in on the cells in the infected brain regions, they could see that the immune system not only determined how the virus spread, but also changed which cell types were infected in the affected regions of the brain.

In cases where the immune system in the brain could not be activated, the researchers found that microglia were infected, affecting their usual task of preventing and clearing infection. In mice that could activate their immune system in the brain, it was mainly nerve cells that were infected. The results underline the importance of the immune system for those infected with TBE.

At the time of writing, there are no treatments for TBE, but the important measures can still be made to prevent infection, such as avoiding tick bites and getting vaccinated. The study highlights the importance of understanding viral pathogenesis and the immune response it triggers to develop effective diagnostic tools, therapies, and preventive measures against TBE.