The United States has developed an experimental vaccine believed to be 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 government announced Wednesday.
Ebola, which has already ravaged several African countries, normally kills 90% of its victims.
”This research has enormous public health implications not only because it might be used to limit the spread of Ebola virus … but also because this vaccine strategy may be applied to other highly lethal viruses, such as the Marburg and Lassa fever viruses and the SARS coronavirus,” commented Anthony Fauci, director of the
National Institute of Allergy and Infectious Diseases.
”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 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 experiment is also seen an an important step toward boosting defences against biological terrorism. 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 Center decided to use findings obtained in the course of their work on the so-called ”prime-boost” vaccine strategy.
The strategy provides for first 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.
But as they worked on the Ebola vaccine, the scientists decided to make a shortcut to the second stage of the process, trading off a weaker immune response for time, which is 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 (DRC).
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.
A hemorrhagic fever that turn tissue into mush, Ebola was first identified in 1976 in southwestern Sudan and in a nearby region of Zaire, as the DRC was then called, where it killed a total of 564 people, according to the World Health Organisation.
Since then, outbreaks of the diseases have been reported in Ivory Coast, Gabon and Uganda. Altogether, the epidemics have caused more than 1 000 known deaths. – Sapa-AFP