http://www.wired.co.uk/news/archive/2013-02/01/tobacco-plant-rabies-cure
A team of molecular immunology researchers has genetically modified tobacco plants to produce highly effective rabies antibodies.
“The reason that most of us in the field are working with plants, is that we all believe that there are huge cost advantages to manufacturing in plants, and that the technology involved is readily transferable to developing countries,” James Ma, chair of the Hotung Molecular Immunology Unit at St George’s University in London, which trialled the technique, told Wired.co.uk. “We believe that production ‘in the region, for the region’ is an important concept for pharmaceuticals for the future.”
According to the World Health Organisation more than 55,000 people die after contracting rabies every year. Most of these deaths occurred in Asia and Africa, in areas where swift access to post-exposure vaccines is limited due to the high cost of manufacturer. “For at least three decades WHO has fought to break the “cycle of neglect” affecting rabies prevention and control particularly in low- and middle-income countries,” the international body states.
Work by the Hotung Molecular Immunology Unit could be one of the first steps to changing that, with its vision for fields of cheap, easily accessible antidotes.
Ma and his team demonstrated two methods for introducing the antibody in their paper published 31 January: to genetically modify plants to produce the murine monoclonal antibody, or by agroinfiltration, whereby new genes are introduced into the plant cells. The first method, Ma tells Wired.co.uk, is technically simple, easy to scale up but you obviously have to wait for the plants to grow. “The latter is technically more demanding, but extremely fast for producing moderate amounts of antibody.”
Before introducing the antibody, the team had to remove some non-human elements from it via molecular engineering — the antibody is derived from members of the rat and mouse family (murine) so they eliminated parts of the sequence that the body could potentially reject.
“It is not necessarily a concern, particularly in the case of a life saving intervention as in rabies,” Ma told Wired.co.uk. “However, it is preferable to eliminate the parts of the protein that would be recognised by our immune systems as being non-human.”
What makes the tobacco plant solution perhaps most attractive, is the ease with which the antibody can be extracted when needed. All you’d need to do it grind the leaves in a solution then purifying it using a technique such as affinity chromatography.
“Tobacco is certainly not the only plant that could be used, but it does have many advantages,” Ma told Wired.co.uk. “It is very easy to work with from a biotechnology point of view. Perhaps more importantly, when thinking about future production, it is not a food crop (so we do not have to be concerned about our genes or antibodies flowing into the food chain), but it is a major world crop, for which a considerable amount of horticultural expertise has already been developed.”
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Written by Liat Clark
Edited by Olivia Solon