Researchers have discovered how West Nile virus enters the brain. The virus induces an inflammatory response in mice that makes the blood brain barrier more permeable and allows viral entry, Erol Fikrig and colleagues report in the December issue of Nature Medicine.
The mosquito-borne West Nile virus (WNV) can trigger brain inflammation, leading to death in some infected people, particularly the elderly. The blood-brain barrier, a specialized structure surrounding the brain, poses a formidable obstacle to most viruses, proteins and cells. The investigators found that a protein called Toll-like receptor 3, which is found on the surface of immune cells, recognizes WNV. Once activated, this protein initiates an inflammatory response resulting in increased permeability of the blood-brain barrier, enabling the virus to cross into the central nervous system. The research may lead to the development of new treatments against the emerging threat of this pathogen, and could also help understand how other viruses-such as Herpes simplex virus-that infect the nervous system invade the brain. Author contact: Erol Fikrig (Yale University School of Medicine, New Haven, CT, USA) Tel: + 1 203 785 2453, E-mail: erol.fikrig@yale.edu Also available online. (C) Nature Medicine press release.
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