Ebola vaccine holds promise
2003-08-07 08:29
Washington - US scientists have developed an experimental vaccine they believe is capable of protecting primates from the Ebola virus in what is seen as a major breakthrough in fighting one of the deadliest diseases known to man, the US government announced on Wednesday.
"After years of developing candidate Ebola vaccines that protected rodents but failed in primates, it is gratifying to have a vaccine that holds great promise for protection of humans," said Peter Jahrling, a researcher at the US Army Medical Research Institute of Infectious Diseases at Fort Detrick, Maryland, a partner in the experiment.
The National Institutes of Health, which announced the experiment, said the fast-acting vaccine was successfully tested on eight macaque monkeys and may one day allow scientists to quickly contain Ebola outbreaks with ring vaccinations, a method used in the past to fight smallpox.
The rub is that the vaccine requiring just one shot has not been tested on humans. But scientists insisted that medicines effective on primates usually have a high likelihood of working on humans.
The breakthrough came when researchers from the Dale and Betty Bumpers Vaccine Research Centre decided to use findings obtained in the course of their work on the so-called "prime-boost" vaccine strategy.
The strategy calls for injecting non-infectious genetic material from the disease-causing microbe into a body to prime its immune system, according to health officials.
A second injection, made several weeks later, delivers attenuated carrier viruses containing key genes from the microbe itself, which usually substantially boosts the immune response.
In working on the Ebola vaccine, the scientists decided to concentrate on the second stage of the process, trading off a weaker immune response for time, which is always a critical factor in combating the fast-spreading disease.
Each of the eight monkeys was given a single boost injection, consisting of attenuated carrier viruses containing genes for Ebola antigens, the officials said.
After waiting a month, they were taken to Fort Detrick where they were injected with various doses of an Ebola virus strain obtained in 1995 from a fatally infected person in what is now the Democratic Republic of Congo.
The shots proved to be a life-saver for all eight animals, even those who received higher doses of the virus, according to the officials.
- AFP