DATE=11/30/00

TYPE=CORRESPONDENT REPORT

TITLE=EBOLA VACCINE (L)

NUMBER=2-269882

BYLINE=JON TKACH

DATELINE=WASHINGTON

INTERNET=YES

CONTENT=

VOICED AT:

INTRO: A group of U-S scientists has successfully tested a vaccine that protects monkeys against the deadly Ebola virus. Their findings - reported in this week's issue of the journal Nature - mark the first time an Ebola vaccine has worked in primates. As V-O-A's Jon Tkach reports, the successful trial is raising cautious hopes that a human vaccine may be on the way.

TEXT: The latest outbreak of Ebola has left more 150 people dead in Uganda since mid-October.

The virus ravages its victims, causing massive internal bleeding that oozes from the eyes and other openings in the body. Most victims die within days after enormous suffering.

Gary Nabel, of the National Institutes of Health, led the successful Ebola vaccine trials reported this week. He says the scientists' work with macaque monkeys will help set the stage for human trials.

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But at the same time, we have to remember there are differences between monkeys and humans, and we will not know for a while whether the experimental conditions are applicable to natural conditions in Africa.

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He says it will be at least three to five years before a human version of the vaccine can even be tested.

The vaccine developed by Mr. Nabel and his team comes in two parts, he says. The first part contains Ebola D-N-A to help to induce an immune system response. The other part is a separate virus that has been re-engineered to mimic a specific component of Ebola. That last part, he says, works to boost the immune system's response.

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The two together form a prime-and-boost combination that gives the immune system a very strong signal, so that when the monkeys are challenged with the virus, they respond to it as though they have seen it before, and then eliminate the virus, and protect them (themselves) against the disease.

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The scientists gave four macaque monkeys the "prime-and-boost" treatment, while another four monkeys in the "control" group did not receive the vaccine.

The four in the control group, Mr. Nabel says, all died within six days of being exposed to the virus. The four macaques that did receive the vaccine have shown no signs of Ebola, he says, now six months after being exposed.

Mr. Nabel says he and his team are hopeful the vaccine will provide broad coverage of the three main strains - or types - of the virus, including the Sudan strain that has been blamed for the latest deadly outbreak in Uganda.

Also, he says, the group's work will not only prove useful for those hoping to tackle Ebola. He says the lessons learned in these and future trials will help scientists understand how to arm the immune system to fight against other deadly viral infections, such as tuberculosis, malaria, and Africa's most potent scourge - H-I-V, the virus that causes AIDS. (signed)

NEB/JON/TDW