New research shows that genetically modified tobacco plants can be used to produce safe protective antibodies against the deadly rabies virus. This may provide a relatively inexpensive cure for rabies, which would benefit patients in developing countries.

In a new study, scientists produced an antibody in transgenic tobacco plants – plants that have been genetically altered – that was shown to neutralise the rabies virus. This new monoclonal antibody works by preventing the virus from attaching to nerve endings around the bite site and keeps the virus from travelling to the brain. Monoclonal antibodies are complex proteins, originally derived from the body’s immune system but in this case made in the plants, to combat diseases.

"Rabies continues to kill many thousands of people throughout the developing world every year and can also affect international travellers," said Leonard Both, a PhD researcher involved in the work from the Hotung Molecular Immunology Unit at St George's, University of London. "An untreated rabies infection is nearly 100 per cent fatal and is usually seen as a death sentence. Producing an inexpensive antibody in transgenic plants opens the prospect of adequate rabies prevention for low-income families in developing countries."

To make this advance, Both and colleagues at St George’s, including group lead Professor Julian Ma, ‘humanised’ the genetic sequences for the antibody so people could tolerate it. Then the antibody was produced using transgenic tobacco plants as an inexpensive production platform. The antibody was purified from the plant leaves and characterised with regards to its protein and sugar composition.

The antibody was also shown to be active in neutralising a broad range of rabies viruses, and the exact antibody docking site on the viral envelope – a membrane that allows the virus to survive outside a cell – was identified using certain rabies viruses.

"Although treatable by antibodies if caught in time, rabies is bad news," said Gerald Weissmann, editor in chief of The FASEB Journal where the research was published. "This is especially true for people in the developing world where manufacturing costs lead to treatment shortages. Being able to grow safe, humanised antibodies in genetically modified tobacco should reduce costs to make treatments more accessible, and save more lives."