Johannesburg - Tobacco might just save your life. Yes, you read that right. Researchers at the Council for Scientific and Industrial Research have pioneered the world’s first injectable plant medicine which could change the way rabies is treated worldwide.
Rabies is a zoonotic (transmitted from animals to humans) disease that is caused by a virus. It is spread to people through close contact with infected saliva, via bites or scratches.
The liquid antidote called RabiVir, made from leaves of the Nicotiana Benthamiana plant – a cousin of the well-known tobacco plant Nicotiana Tabacum – was created with two things in mind: reducing rabies treatment costs and increasing efficacy. But it didn’t come to being overnight.
It all began eight years ago, said Dr Ereck Chakauya, the lead researcher on the project.
“When we got our proof of principle, we got funding from the Technology Innovation Agency. We submitted our business idea under its bio-entrepreneurship programme and won first prize – R15 million to conduct the research,” he explained.
However, Chakauya and his team, including principal investigator Rachel Chikwamba, Nomali Zungu and Fani Marais, knew it would also take help from people who were specialists in fields of plant sciences, viruses, veterinary sciences, bio-processing and bio-pharmaceuticals to bring their concept to life.
Enter the plant protein processing company Kentucky BioProcessing, Mapp Biopharmaceutical and the World Health Organisation.
RabiVir was created to treat people with a third-category wound – meaning a deep bleeding wound – resulting from a bite from a rabid animal.
“Normally in the country, people with second and third-category wounds are treated by injecting an antibody called HRIG (human rabies immune globulin) after being exposed to rabies. But some religions don’t believe in taking vaccines with human blood, and it’s also a challenge to get blood donations as some of the blood donated is unusable,” Chakauya said.
Treatment of rabies using HRIG costs about R3 000, and one would need four injections of the vaccine about every three days.
However, RabiVir can reduce treatment costs up to 10 times, making it more affordable to more people.
The reasons why the plant was used?
“The agronomy (how to grow it) is well understood… we also know its genetics, so breeding can be done. It also has acceptable protein sugars which are allowed in humans. It also has a good biomass; you can grow it under controlled conditions; it’s not a feed crop, so it will not impact the food chain; and it happened to do what we wanted it to do,” Chakauya said.
Asked how RabiVir works, Chakauya explained that it binds the virus at the site of entry. “It is a cocktail of antibodies that neutralise the virus and kills it.”
The tobacco plant is grown for about five weeks and is then introduced to the genes. “We can make the product available within a short period of time because the plant material is already there,” he said.
But it will still be a while before RabiVir is used in the country. Chakauya said that while they had conducted tests on hamsters, which were all successful, clinical trials on humans still needed to be done, and it could still be another eight years before it can be used.
For now, proving the concept Chakauya’s team came up with eight years ago is fuel enough for them to keep going.
“It’s exciting,” he said with a smile. “When you work in the lab, you know what you want, but sometimes it doesn’t quite come out how you want it. But when you have something that brings the results you had hoped for, it’s encouraging.” - The Star