Antibody for West Nile virus shows promise

Researchers have developed an antibody that can cure mice of West Nile virus (WNV) infection, a disease for which no specific treatment exists, the National Institute of Allergy and Infectious Diseases (NIAID) has announced.

West Nile virus is a disease which has no symptoms or only a mild flu-like illness in most people, but for some infected, about 1 in 150, the virus invades the central nervous system and can be fatal.

The US had 2,470 reported cases of West Nile disease in 2004, with 88 deaths, according to the Centers for Disease Control and Prevention.

Now a team at Washington University in St. Louis have developed an antibody with infection-fighting characteristics that mimics one produced by people whose immune systems successfully fend off the West Nile virus. The antibody has been tested in mice and its success warrants further development and testing in people with West Nile disease.

The research was prompted by the discovery that antibodies taken from the blood of people who had recovered from West Nile fever could cure mice infected with WNV. This revaluation made the researchers decide to develop their treatment, a monoclonal antibody.

In order to solve the problem of antibodies derived from human blood, which vary in their ability to fight disease, and can be accompanied by other potentially dangerous infectious agents, despite efforts to purify them, the research team "made 46 monoclonal antibodies against West Nile virus and then eliminated the less effective ones through a tedious molecular-level screening process". Then they worked with MacroGenics to create a human-like version of the most effective antibody.

According to a statement "MacroGenics stitched the part of the antibody that cripples the West Nile virus into the scaffold of a human antibody, the monoclonal antibody was several hundred times more potent in cell culture tests than antibodies obtained from people who had recovered from West Nile virus infection."

Senior investigator Michael Diamond, MD, PhD, says this antibody could be given to mice as long as five days after infection, when West Nile virus had entered the brain, and it could still cure them, and it also completely protected the mice against death.

The research, funded in part by the NIAID, is described in a report published online yesterday by Nature Medicine.