Infection with West Nile Virus (WNV) can cause lethal encephalitis and there are currently no vaccines or specific therapeutics for use in humans.
However, data generated by Erol Fikrig and colleagues at Yale University School of Medicine has provided evidence that the proinflammatory soluble factor MIF might provide a target for developing therapeutics to treat WNV encephalitis.
Infection with WNV was shown to increase the amount of MIF in the plasma and spinal fluid of humans and the amount of MIF found in the spleen and brain of mice. In mice, an absence of MIF activity increased survival after infection with WNV and in MIF-deficient mice this was associated with decreased viral load and decreased infiltration of immune cells into the brain in the early stages of encephalitic disease. As viral load and immune cell infiltration in the brain increased at later time points after infection with WNV, the authors suggested that delayed viral neuroinvasion in the absence of MIF allowed the virus to be cleared in the periphery and thus survival was enhanced.