According to a new study, a team of scientists used special gene-silencing drugs to selectively "knock out" viral proteins in Chinese rhesus macaques infected with a lethal dose of the Zaire Ebola virus. Zaire is the most virulent strain of Ebola—90 percent of infected people die during outbreaks.

(Related: "Where Does Ebola Hide Between Epidemics?")

Ebola spreads via bodily fluids or tainted needles and razors, and it's highly contagious. Infections in humans and other primates typically cause acute fever and headaches, followed by uncontrollable bleeding from the body's openings. Shock from heavy internal and external bleeding usually proves fatal.

Since the virus emerged in central Africa in the late 1970s, people have been searching for