Washington, May 17 (IANS): Researchers have identified an antiviral compound which can help protect the brain from the West Nile virus that can cause a serious neurologic illness.

"We have identified a new antiviral compound that does not involve directly attacking a virus but stems viral invasion into the brain," said co-senior author Robyn Klein, professor of medicine at Washington University School of Medicine in St. Louis.

The compound, produced naturally in the body in response to infection, tightens the blood-brain barrier, making it harder for the virus to invade the brain.

The blood-brain barrier is a natural defence system that is supposed to keep pathogens out of the brain. No treatments exist for the virus, which crosses the blood-brain barrier in an estimated one percent of infected people, causing a neurologic illness such as encephalitis or meningitis that can be fatal.

The scientists studied mice that lacked the antiviral compound. Compared with normal mice, the mice without the compound had higher levels of West Nile virus in the brain.

The researchers found the blood-brain barrier was much more permeable to the virus in these mice. The scientists then gave normal mice West Nile virus along with the anti-viral compound.

The mice received the antiviral compound at the start of the infection and two and four days later. Typically less than 20 percent of normal mice survive such a high dose of the virus, but survival rates rose to more than 40 percent after treatment with the antiviral compound.

The findings appeared online in the journal Science Translational Medicine.