Genetically-modified tobacco plants grown by Mapp Biopharmaceutical Inc. in Kentucky are believed to help develop an effective treatment for the Ebola virus now spreading across West Africa.
Two infected US medical workers received an experimental treatment containing the antibodies in Liberia last week, after it was tested on lab animals. After receiving doses of the drug, both patients' state has improved.
If the lab tests confirm the effectiveness of the treatment, producing monoclonal antibodies with tobacco plants could become a cost-effective method of fighting the Ebola virus.
'Tobacco makes for a good vehicle to express the antibodies because it is inexpensive and it can produce a lot,' said Erica Ollmann Saphire, a professor at The Scripps Research Institute and a prominent researcher in viral hemorrhagic fever diseases like Ebola. 'It is grown in a greenhouse and you can manufacture kilograms of the materials. It is much less expensive than cell culture.'
Creating antibodies in tobacco plants starts with mice, which receive a vaccine carrying Ebola virus proteins. Researchers select the best antibodies, before testing them on mice, and then on monkeys. The experimental drug called ZMapp contains three antibodies, which alert the immune system and neutralize the Ebola virus.
Tobacco plants are used as hosts to grow the antibodies: the desired antibody genes are fused to genes for a natural tobacco virus. As the tobacco plants are infected with this new virus, antibodies are grown inside the plant, and finally extracted.
Growing antibodies in plants is safer than in mammals, because 'plants are so far removed, so if they had some sort of plant virus we wouldn't get sick because viruses are host-specific,' said Qiang Chen, a plant biologist at Arizona State University in Tempe, Arizona.
Mapp CEO Kevin Whaley said manufacturing process would have to be cleared by the US Food and Drug Administration as part of the approval process.
