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The BBC's Science correspondent, David Concar
"All the signs are encouraging"
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Wednesday, 29 November, 2000, 19:01 GMT
Vaccine protects monkeys from Ebola
Ebola NIH
Ebola is one of a family of so-called filoviruses
Researchers have produced a vaccine that will protect monkeys from the Ebola virus.

Although much more work needs to be done, we hope this moves us closer to new vaccines and treatments for Ebola

Dr Gary Nabel
It raises the hope that a human vaccine can now be developed using the similar approach.

Although other viral diseases claim more lives each year, Ebola is greatly feared because of the way it can sweep through a population.

The deadly microbe, which was first identified in 1976, periodically attacks African villages and will kill up to 90% of those it infects.

Victims die very quickly, suffering severe pain, high fever and extensive internal bleeding. A recent outbreak in Uganda has killed more than 150 people to date.

Lethal dose

"Doctors have essentially been helpless against Ebola virus," said lead researcher Dr Gary Nabel, director of the Dale and Betty Bumpers Vaccine Research Center (VRC) at the US National Institutes of Health.

An Ebola suspect being assisted to a local hospital
Ebola spreads through human contact
"Our studies show that animals can launch an effective immune response against Ebola virus, and we can use knowledge of this response to design a vaccine that protects non-human primates from infection.

"Although much more work needs to be done, we hope this moves us closer to new vaccines and treatments for Ebola and other viruses."

The new vaccine was tested at a high-containment facility run by the US Centers for Disease Control and Prevention.

The researchers, who report their work in the journal Nature, exposed eight macaques to a lethal dose of Ebola. Only the four animals given the new vaccine survived.

Boosted effect

The vaccine worked on two levels. First, the monkeys were given injections of DNA that produced in their systems certain proteins found on the surface of the virus. These were sufficient to stimulate an immune response but did not make the animals ill.

The response was then boosted by exposing the macaques to a modified cold virus that had been re-engineered to express another specific component of the virus. This further increased the production of antibodies and T cells in the animals to fight infection.

More than six months after being exposed to Ebola, the four monkeys in the study remain symptom-free with no detectable virus in their blood.

"We of course want to test the multivalent vaccine for effectiveness against all three strains of Ebola virus," said co-researcher Dr Nancy Sullivan, "but we also need to look more closely at the immune response induced by these vaccines so we can nail down what is needed for protection."

News of the research has received a broad welcome. Dennis Burton and Paul Parren at the Scripps Research Institute at La Jolla, California, commented in Nature: "There's still some way to go before a human vaccine is available, but this is a step in the right direction."

If a human vaccine does emerge, it could be administered swiftly to local people in an area where the virus has broken out, as well as medical and support personnel who travel there, they said.

But a more urgent requirement is to channel resources into surveillance, hygiene and training in barrier nursing, "which can be highly effective in containing an outbreak," they noted.

Ebola is named after the town in Zaire (now the Democratic Republic of Congo) where it was discovered 24 years ago, possibly after leaping the species barrier from animals. It is one of a family of so-called filoviruses.

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See also:

23 Nov 00 | Africa
Ebola test for Uganda's wildlife
31 Jul 00 | Health
Breakthrough on Ebola
02 Mar 00 | Sci/Tech
Ebola cure possible
16 Aug 99 | Medical notes
Ebola and other tropical viruses
18 Oct 00 | Health
Africa's emerging virus threat
20 Oct 00 | Africa
In pictures: When Ebola struck
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