February 5, 2009

Proteins defend against West Nile

U.S. researchers have identified molecular interactions that govern the immune system's ability to defend the brain against West Nile virus.

The researchers at Cedars-Sinai Medical Center in Los Angeles and Yale University in New Haven, Conn., said that the finding offers the possibility that drug therapies could be developed to improve success in treating West Nile and other viral forms of encephalitis -- a brain inflammation illness that strikes healthy adults and the elderly and immunocompromised.

In a series of laboratory experiments and studies in mice, the research team found that a specific molecule and signaling pathway are critical in detecting West Nile virus and recruiting specialized immune cells that home to and clear infected cells.

In mice genetically engineered to lack this molecular pathway, immune cells were detected at a distance but they didn't home to brain cells infected by the virus, the study said.

Transmitted to humans by mosquitoes, West Nile virus is the most common cause of epidemic viral encephalitis in North America and has become a worldwide public health concern. While most healthy people who contract the virus have few if any symptoms, an infection can result in life-threatening brain disease -- particularly in the elderly and those with compromised immune systems, the researcher said.

The study is published online in the journal Immunity.