The observation that drove this research was mothers who had taken the drug thalidomide during pregnancy, sometimes had children with autism. Some of these same children also had misshapen ears, as well as abnormalities in the nerves of the head and face. Previous studies of these children suggested that the damage to the ears and facial nerves resulted between the 20th and the 24th days after conception. This time span marks the development of brain regions that later control the muscles of the eyes, face, tongue, jaw, and throat. Ebola virus kills quickly, giving the body little time to launch an effective immune response.
Infected individuals suffer severe pain, high fever and extensive internal bleeding.
Although the virus periodically strikes humans, it is not known where Ebola resides in nature between outbreaks. Ebola is a difficult virus because currently available antiviral drugs have no proven effect, and since its natural reservoir is not known, environmental control is impossible. In earlier studies, genetic Ebola vaccines, strands of DNA containing genes that encode Ebola virus proteins, were tested for their ability to induce immune responses in rodents and to protect against disease. Unlike traditional vaccines typically made from viral proteins, DNA vaccines more closely mimic virus infection because they enter a cell and use that cell's machinery to manufacture new viral proteins. In rodents, it was shown that a DNA vaccine could protect mice and guinea pigs from a specially adapted Ebola virus strain lethal to rodents.