Vaccine is first treatment for Ebola-like virus

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Vaccine is first treatment for Ebola-like virus

Wed Apr 26, 2006 11:37 PM BST

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - A vaccine that protects monkeys against the highly

deadly Marburg virus, a relative of Ebola, may also provide the first known

treatment for the infection, researchers reported on Wednesday.

Now they hope to use a similar vaccine to try to treat Ebola. Both viruses

have caused rare, but frightening and deadly, outbreaks in Africa and both

are considered to be potential bioterror agents.

The vaccine was created using a harmless virus known as vesicular stomatitis

virus, or VSV. The researchers took out one gene and replaced it with a key

gene from Marburg virus.

When they infected monkeys with Marburg and then administered the vaccine,

the monkeys were protected and stayed healthy, said Geisbert of the

U.S. Army Medical Research Institute of Infectious Diseases.

Unvaccinated monkeys died within 10 to 12 days.

" We were very surprised, " Geisbert said.

Geisbert, whose team worked with colleagues at the National Microbiology

Laboratory at the Public Health Agency of Canada, published the findings in

this week's issue of the Lancet medical journal.

He said it may be a while before the vaccine is tested in people but hopes

it is a first step.

Marburg virus killed more than 300 people -- 90 percent of those infected --

in Angola last year. Ebola is usually somewhat less deadly and killed 254

people between 2001 and 2005 in Gabon and the Democratic Republic of Congo.

There is no cure for either diseases, both caused by a family of viruses

known as filoviruses. They lead to a particularly nasty form of hemorrhagic

fever and victims usually die of multiple organ failure and shock.

WORST-CASE SCENARIO

A few victims have been lab or medical workers experimenting with the virus

or trying to help patients who suffered " needle-stick " accidents that tend

to infect the victim with a large dose of virus.

" In the 1976 Ebola outbreak in former Zaire (now the Democratic Republic of

Congo) there were 85 confirmed needle sticks because they were re-using

needles. All 85 folks died that got stuck with a needle and the disease

course went faster, " Geisbert said in a telephone interview.

" In a real-world situation most folks are going to be exposed to much lower

doses of virus by different routes. "

If the vaccine was so effective in monkeys given high doses of virus, it

should be effective in an outbreak scenario in which people typically get

lower doses, Geisbert said.

Close contact is needed to transmit both Ebola and Marburg. Geisbert said

relatives preparing a victim for burial often become infected, possibly

through infected blood getting into small cuts or abrasions, or by touching

blood or other bodily fluids and then touching the nose, mouth, lips or even

eyes.

It may take some time to develop and license a human vaccine, but Geisbert

said it may be possible to use an experimental version in case of a lab

accident.

It is not certain whether a similar vaccine against Ebola will be as

effective because of small but significant differences between the viruses,

Geisbert said.

He also said Wyeth was testing a similar vaccine approach for the AIDS

virus.