West Nile Virus: The Bite That Can Kill
Why do some people exposed to West Nile virus get deathly ill and others emerge unscathed? In a study that both helps to answer that question and could point the way toward prevention and effective treatment, scientists at Yale University have isolated deficiencies in the immune system that create increased susceptibility to infection by the West Nile virus. Their work appears in the February 20 issue of Immunity.
West Nile has emerged as the most common cause of mosquito-borne viral encephalitis in North America and is a public health concern around the world. The elderly and people with compromised immune systems are especially at risk for life-threatening neurological diseases such as encephalitis and meningitis as a result of infection with the West Nile virus. An approved therapy does not yet exist.
The Yale team looked at the sophisticated interplay of immune system sensors in mice that are supposed to recognize infectious agents and combat them. Mice with detection and response systems that were compromised had much greater susceptibility to a lethal infection of West Nile. Their immune systems could not muster the strength to take aim at the infection and fight it off.
Dr. Erol Fikrig, an author of the study, said, “we are optimistic that the same mechanisms will be important in human infection.”
The Yale team’s findings may also offer a key to developing a treatment aimed at stimulating specific agents of the immune response to West Nile that fail when they are most needed, putting the elderly and those with compromised immune systems at greater risk of dying.
But, Fikrig cautioned, “Therapy for West Nile encephalitis is likely to be very challenging because it is important to administer treatment before the full-blown disease has developed, and this is not always possible.”
The research was conducted at the Yale School of Medicine in the laboratories of Richard A. Flavell, Department of Immunobiology and Erol Fikrig, M.D., Department of Internal Medicine. Lead researchers were Terrence Town, formerly of the Yale School of Medicine and currently with the University of California, Los Angeles Department of Medicine, and Fengwei Bai of the Yale School of Medicine.