Two US aid workers that contracted the Ebola virus in Liberia are said to be improving after receiving an experimental treatment, ZMapp, which had never been tested in humans before. While we cannot be certain that ZMapp is attributable to this improvement, the treatment yielded promising results in nonhuman primate studies. Rather than being a synthetic drug, ZMapp is actually an antibody therapy consisting of a cocktail of three different antibodies to the Ebola virus. And it’s made in a rather intriguing way- within plants.

Inside massive greenhouses in Owensboro, Kentucky, thousands of tobacco plants are being grown by a company called Kentucky BioProcessing (KBP). These plants, called bioreactor plants, are being used to produce a variety of proteins for pharmaceutical products, for example vaccines and antibodies against certain disease causing organisms. KBP has actually been selected to produce therapeutic proteins for a variety of health threats, for example flu, rabies, HIV and HPV.

How does it work? Researchers start by inserting a desirable gene, for example a gene encoding a particular antibody, into a plant virus. The tobacco plant is then infected with the virus and consequently infected cells start to produce the proteins which are eventually extracted and purified into a serum. This is similar to how we use bacteria as protein making factories, for example by inserting the human insulin gene into E.coli in order to produce synthetic insulin for individuals with diabetes.

Bioreactor plants are proving to be extremely useful in the production of various therapeutic proteins. They’re faster, more efficient and cheaper to use than traditional methods that require complex bioreactors. Tobacco plants also grow quickly which makes scaling-up production easy.

Although ZMapp has not yet been approved for use as human trials have not been conducted, according to Kentucky.com KBP has started increasing production in anticipation of further trials this year.