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Experimental Ebola Serum Grown in Tobacco Leaves

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WebMD Health News

Aug. 4, 2014 -- ZMapp, the experimental treatment rushed to two Americans infected with Ebola in Africa, is grown in specially modified leaves of tobacco -- a plant better known for harming health than healing.

“We complied with a request from Emory University and Samaritan’s Purse to provide a very limited amount of ZMapp last week,” says David Howard, a spokesman for Reynolds American Services, the parent company of Kentucky BioProcessing. The small biopharma company in Owensboro, KY, has been contracted to grow the drug.

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Making the serum is slow, in part, because the plants must be grown for several weeks before they are “infected” with a type of protein. “Basically the plants act like a photocopier of the proteins,” Howard says.

Once they’re infected, Howard says it takes a week for the plants to make enough of the protein to harvest and distill into a useable drug.

“Talk about transforming tobacco,” Howard says.

Serum Hadn't Been Used in Humans Before

Based on the interest in the serum, Howard says Kentucky BioProcessing is actively working on ways to scale up its production.

But before it can be used on a wider scale, it must first go through the formal drug approval process with the FDA. Howard says the plan was to begin that process later this year.

The compound used to treat Dr. Kent Brantly and Nancy Writebol was only formulated in January, according to Larry Zeitlin, PhD, president of Mapp Biopharmaceuticals, the California company that co-developed the drug.

It has been tested in monkeys, but had never before been given to human patients before it was rushed to Brantly and Writebol.

Zeitlin says he hasn’t even had a chance to publish a scientific paper on the compound, which is a combination of three antibodies that are thought to help in two ways. 

One of the antibodies alerts the immune system to infected cells so they can be destroyed, says Erica Ollmann Saphire, Ph.D. She's a professor of immunology at the Scripps Research Institute in La Jolla, CA. She’s been given a government grant to study the antibody cocktail.

Saphire says the other two antibodies probably prevent the virus from making more copies of itself. “We’re still trying to figure out exactly how it works,” she says. “But it seems to neutralize the virus.”

Cautious Optimism

Other experts who study Ebola urged caution with reports of Dr. Brantly’s dramatic recovery on the drug.

Thomas Geisbert, MD, professor of infectious disease at The University of Texas Galveston Medical Branch, has been studying the Ebola virus since 1988.

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