A recent study conducted by researchers from the University of Colorado and the University of Bourgogne has shed light on the spread of herpes simplex virus type 1 (HSV-1) in the brain.

Using a mouse model, the research focused on two primary routes of entry for HSV-1: through the brainstem and the olfactory nerve.

The findings revealed that HSV-1 can spread to several brain regions, including the brainstem, midbrain, and hypothalamus, while typically avoiding the hippocampus.

Interestingly, regions such as the hippocampus and cortex, which are crucial for memory and attention, showed no signs of HSV-1 antigens.

Researchers mapped HSV-1's travel within the brain, identifying critical areas affected, including the brainstem, which governs sleep and movement, and the hypothalamus, responsible for appetite, sleep, mood, and hormonal regulation.

The virus specifically targets key brain regions, impacting functions related to mood and hormonal control.

Despite not causing full-blown encephalitis, HSV-1 can impair the function of affected brain regions, according to lead researcher Christy Niemeyer, PhD.

This chronic inflammation caused by HSV-1 is a potential trigger for neurological disorders, emphasizing the need to understand its role in brain health.

The full study detailing these findings has been published in the Journal of Virology, accessible via DOI: 10.1128/jvi.00968-24.

In a broader context, a 2015 report by the World Health Organization indicated that 67% of the global population under 50 is infected with HSV-1, which can remain dormant in the peripheral nervous system after initial infection.