Herpesvirus gets to brain via nose: olfactory cells provide path for virus, researchers suggest.
After setting up shop in people's nasal mucus, human herpesvirus 6 may travel along olfactory cells right into the brain, researchers report August 16 in the Proceedings of the National Academy of Sciences.
HHV-6 causes the common childhood infection roseola, marked by a chest rash and a high fever. "Everyone is exposed to this," says study coauthor Steven Jacobson of the National Institute of Neurological Disorders and Stroke in Bethesda, Md. "You have it. I have it."
Despite the virus's ubiquity, very little is known about it. In some people (researchers don't know how many), the virus can infect the brain, where some scientists believe it may contribute to neurological disorders such as multiple sclerosis and a form of epilepsy.
Other viruses such as herpes simplex, influenza A and rabies can invade the brain by shooting through the nose, so Jacobson and his team wondered whether HHV-6 could do the same.
Researchers found high levels of HHV-6 in the olfactory bulb, a smell-related part of the brain, in two of three autopsy brain samples. The team then looked at nose mucus and found the virus in 52 of 126 samples. "We were surprised to find so much in the nasal mucus" Jacobson says.
In a lab dish, specialized cells that help connect nerves in the nasal cavity to the brain were susceptible to HHV-6 infection, the team found. These cells might be a route of entry for the virus, Jacobson says.
"Viruses take advantage of whatever they can," says NINDS neurologist Avindra Nath, who was not involved in the study. "They'll try to gain entry any way they can, so it's not surprising that they'd use nasal mucosa to do so."
The study presents data on a small number of samples, cautions neuroimmunologist Robyn Klein of Washington University School of Medicine in St. Louis, so it's hard to say whether HHV-6 really travels along an olfactory pathway into the brain. Confirming the nose-to-brain passage is important, Klein says, because a virus's entry point to the brain may have a big impact on the infection's outcome.
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|Title Annotation:||Body & Brain|
|Date:||Sep 10, 2011|
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