An outbreak has killed 149 people in Uganda this year, and a 1995 one in Zaire claimed 245 lives. Some fear the virus, which can spread by bodily contact, could be carried elsewhere by terrorists or sick airplane passengers. A vaccine is the best hope for protecting humans from infection. None of the primates that received the vaccine showed signs of illness during the six-month study. Vaccines attempt to marshal the body's immune system to build defenses by showing it what the targeted virus looks like.
Traditional approaches involve inoculating with dead germs or live but weakened ones.
In 1997, Nabel and others developed a strategy that protected guinea pigs by using a vaccine made of DNA strands that encode Ebola virus proteins. The approach worked in rodents but was not completely effective for primates. In the latest research, Nabel and colleagues boosted the DNA vaccine with a weakened virus that normally causes respiratory infections. The strain was modified with a protein of the Ebola Zaire strain. The one-two punch worked.