However, Dr Jonathon Stoye, head of virology at the UK's National Institute for Medical Research, suggested the results should be interpreted cautiously.

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Professor Robin Lovell-Badge, of the MRC National Institute for Medical Research, said it often took 15 to 20 years to develop a therapy.

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But according to Professor Robin Lovell-Badge, of the National Institute for Medical Research in Mill Hill London, people should not worry unduly over the germ-line alterations.

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Professor Robin Lovell-Badge, a geneticist at the National Institute for Medical Research, told the BBC it was vital scientists were able to import animals, so they could collaborate with colleagues abroad.

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Dr Delmiro Fernandez-Reyes, head of the division of parasitology at London's National Institute for Medical Research, welcomed the research, presented at American Society of Tropical Medicine and Hygiene meeting in New Orleans.

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Professor Robin Lovell-Badge, of the Medical Research Council's National Institute For Medical Research, said the work was exciting, but work was required to end the reliance on viruses, and to tease out why two different techniques produced similar results.

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Professor Robin Lovell-Badge, geneticist at the National Institute for Medical Research, said that in reality the number of imported animals such as mice that are used in research is very small because a pair are bred when they are brought into a lab.

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The researchers from McGill, along with scientists from France's National Institute for Health and Medical Research, analysed DNA samples from almost 200 Vietnamese families who had a history of leprosy.

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He was a student at the National Institute of Scientific Research and was conducting research on nanosensors, which are used primarily for medical treatments or to build other nanoproducts, she said.

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