The tobacco plant family has turned over a new leaf – to save lives. CSIR researchers have genetically engineered a microfactory to produce the world’s first injectable medicine from a plant: a rabies antidote 10 times cheaper and potentially far more effective than the currently available cure.
The CSIR has pioneered the world’s first injectable plant medicine. Researchers have genetically engineered the micromachinery of a leafy tobacco plant to churn out a cocktail of life-saving drugs. Their flagship product is an antidote to the deadly bite of a rabid dog. It’s called Rabivir and it doesn’t just match the only other available product on the South African market against rabies, it betters it by far.
Dr Ereck Chakauya leads the Rabivir research at the CSIR and says that deaths caused by rabies are vastly underestimated, especially since developing countries often have stray dog overpopulation.
“By my approximation there are about 9 million dogs in South Africa, and some researchers say there may be up to 2 000 bites per day, many [of the victims] kids.” He believes many deaths caused by rabies may go unnoticed since diagnosing the disease after the victim has died requires laboratory tests. The disease can also be mistaken for cerebral malaria. If the virus is not stopped in its tracks soon after the bite, death is virtually inevitable. Victims need help before the flu-like symptoms of the disease start showing. Treatment involves taking preventative medication as soon as possible after suspected infection. This is known as post-exposure prophylaxis (PEP) and, in the case of rabies, consists of a cocktail of antibodies and a vaccine. Every year around 20 million people receive this treatment. In South Africa, a single non-profit company currently produces the antibodies from human blood. An average adult male would need about five vials, setting him back about R3 000. He would also need four injections of the vaccine, which is more readily available but still costs about R300 per jab. If South Africa has trouble affording the drugs, other African countries are almost certainly worse off, says Chakauya.
Rabivir is an alternative to the antibody component of the PEP. What GreenPharm, the proposed spin-off company of this
research has effectively done, is to reduce the cost of the antibody treatment from R3 000 to just R200, while still being profitable.
Simpler, better, faster
Apart from being both cheaper and more effective than current drugs, Rabivir could also solve a few other problems unique to developing countries. For example, human blood donations are prioritised for lifesaving transfusions, not for the production of anti-bodies. Blood is a scarce resource in the first place since much of it is infected with HIV and hepatitis B and must thus be discarded. Certain African countries make the antibodies from horse blood, but this
may cause an allergic reaction in the patient. Some religions are against using blood-based products at all.
The CSIR scientists worked closely with the World Health Organization, and other partners like Kentucky BioProcessing and MAPP Biopharmaceuticals, to address these challenges. Since it was already known which antibodies worked against
rabies, their genetic codes were engineered into Nicotiana benthamiana plants, a cousin of the commercial cigarette tobacco plant Nicotiana tabacum. The research group’s first attempts produced just below ten milligrams of antibody per kilogram of leaves. Now, after some clever genetic tweaking, they have increased the yield substantially. GreenPharm is currently seeking funds to complete pre-clinical trials. The trials will test whether Rabivir is safe for healthy humans. The antibodies will also be further tested against rabies strains specific to Africa and Asia. Potential partners include companies which currently only manufacture the vaccine component of the PEP. Chakauya and his fellow inventors, Dr Rachel Chikwamba and Dr Tsepo Tsekoa, hope Rabivir will be on African and Asian markets within five to 10 years.
A steep curve to the top
“There’s a lot of learning that came out of this,” he says, referring to lessons in drug research and development from
the CSIR’s more experienced international partners. Chakauya also highlighted the important role of funding from
the Technology Innovation Agency. Now, GreenPharm not only has a potential commercial product, it also has the tools and skills to create other drugs and vaccines using the same genetic engineering techniques. For GreenPharm, Rabivir is
just the beginning.
A combination of patents, licences and know-how
Team / Inventor:
Dr Ereck Chakauya: firstname.lastname@example.org
Contact: Fanie Marais