A recent study showed that the dreaded tick-borne encephalitis (TBE) virus infects different types of brain cells in different parts of the brain, depending on whether the immune system of the affected person is activated or not. TBE is classified as a virus-borne illness by the Centres for Disease Control and Prevention in the United States. The virus enters humans through a tick bite or by eating or drinking unpasteurized dairy products (milk and cheese) from infected goats, sheep, or cows.

In the study, the researchers mapped the pathways of how the TBE virus infects the brain to cause encephalitis by developing a three-dimensional method. The method determined the location of viruses in the brain and which specific parts of the brain have been infected with the TBE virus.

The 3D method is based on information obtained from brain images combined with studies of gene expression in different cell types. The findings of the study showed that the virus infected different regions of the brain depending on the innate immune system of the test subject. When the researchers focused their attention on the cells in the infected brain regions, they discovered that the immune system not only influenced how the virus propagated but also altered which cell types were infected in the afflicted brain regions.

When the researchers zoomed in closer, they discovered that in situations where the immune system in the brain could not be triggered, the brains immune cells, microglia, were infected. However, in test subjects who could activate their immune systems in the brain, it was mostly nerve cells that were infected.

The innate immune system is already recognized to have a significant role in preventing TBE virus damage to the brain, but it has been unclear where and which cells they infect. The findings highlight the relevance of the immune system in patients afflicted with TBE. 

(Source: https://www.hindustantimes.com/lifestyle/health/tickborne-infection-impacts-various-cell-types-in-brain-study-101681802489000.html )