RNA nasal spray subdues brain infection

West Nile fever is a viral infection typically spread by mosquitoes. In about 75% of infections people have few or no symptoms. In less than 1% of people, encephalitis or meningitis occurs, with associated neck stiffness, confusion, or seizures. Recovery may take weeks to months. The risk of death among those in whom the nervous system is affected is about 10%. 

Designer RNA molecules delivered through the nose show early promise for treating West Nile fever, trials in mice show.

No effective therapies exist for the illness caused by a mosquito-borne virus, which can invade the brain. Priti Kumar at Yale University School of Medicine in New Haven, Connecticut; Sang Kyung Lee at Hanyang University in Seoul; and their colleagues developed a small RNA molecule that stymies reproduction of the virus. The researchers then attached the RNA to a molecule known to shuttle cargo into neurons.

The team administered the experimental therapy to mice using a nasal spray. In animals with late-stage brain disease, treatment greatly lowered viral concentrations in the brain and increased survival rates compared with untreated animals. Survivors also developed long-term protection against future infection.