US researchers have discovered that the herpes simplex virus type 1, which causes cold sores, is able to spread through the central nervous system and target specific brain regions.
- Herpes simplex virus type 1 (HSV-1) spreads to the brain after infecting the nasal passages in mice.
- It is found in regions of the brain that produce serotonin and norepinephrine, as well as the hypothalamus, a critical center of appetite, sleep, mood and hormonal control in the brain.
- When the virus interacts with immune cells in the central nervous system, they become inflamed, which can lead to chronic inflammation, a known trigger for neurological and neurodegenerative diseases.
On the lip, more precisely at the junction between the skin and the mucous membrane, they recur more or less regularly. Cold sores are viral rashes that form a cluster of blisters. They are caused by a virus from the Herpes group, called “Herpes simplex virus 1 (HSV1)”, present in the body since an old primary infection. “Recently, it has been implicated in neurodegenerative diseases, such as Alzheimer’s disease, but no clear pathway for invasion into the central nervous system has been established,” declared Christy NiemeyerMD, assistant professor of neurology at the University of Colorado Anschutz Medical Campus (United States). This is why the researcher and her team wanted to determine how the herpes labialis virus can enter the brain and which brain areas are the most vulnerable.
Herpes labialis: the virus enters the brain and interacts with its main immune cells
As part of one study, scientists conducted an experiment on mice. After introducing the HSV1 virus into the nasal passages of rodents, they mapped where and how this pathogen travels through the olfactory epithelium, the central nervous system and infects critical regions that control many vital functions, such as the trunk brain, which controls sleep and movement. “We found spread of HSV-1 in the olfactory epithelium and underlying tissues, accompanied by an inflammatory response from macrophages (cells of blood origin)”can we read in the results published in the journal Journal of Virology.
The authors also found the herpes labialis virus in regions of the brain that produce serotonin and norepinephrine, as well as in the hypothalamus, a critical center of appetite, sleep, mood and control. hormonal in the brain. “In each area of the brain, activation of microglia (a population of innate immune system cells specific to the central nervous system) also varied considerably,” they clarified. Christy Niemeyer added that persistently inflamed cells can lead to chronic inflammation, a known trigger for a number of neurological and neurodegenerative diseases.
“Better understand how viruses interact with the onset of neurological diseases”
So even if the presence of HSV-1 does not cause full-blown encephalitis in the brain, it can still affect the functioning of these regions, according to the team. “This research offers important avenues to better understand how viruses interact with overall brain health as well as the onset of invasive neurological diseases.”
