Two scientists who discovered a means of switching off genes that promises new treatments for cancer, HIV and other diseases were rewarded today with the Nobel Prize for Medicine, just eight years after they first published their work.

Andrew Fire and Craig Mello, both Americans, shared the 10m Swedish Kronor (£724,000) award for developing RNA interference (RNAi), a technique for controlling how the effects of DNA are activated inside cells.

The method has revolutionised fundamental biology since it was first put forward in 1998, and is widely considered to have huge potential for treating disease.

It should ultimately allow the design of drugs that switch off the genetic mutations that turn cells cancerous, and to attack viruses and bacteria by stopping their genes from sending the signals they need to survive, reproduce and damage human tissue.

The award is unusual because the Nobel Committee is notorious for waiting decades before conferring the most prestigious prizes in science. In 2003, for example, the British scientist Sir Peter Mansfield shared the Nobel Prize for Medicine for his contribution to the development of magnetic resonance imaging scanning, which came from work he did in the 1970s.

Dr Fire and Dr Mello published their key paper in the journal Nature only in 1998, and RNAi has yet to produce any direct clinical benefits for patients. The decision to recognise them with a Nobel now is a measure of the impact scientists expect the technique to have.

Dr Mello said today: "I knew it was a possibility, but I didn’t really expect it for perhaps a few more years. Both Andrew and I are fairly young, 40 or so, and it’s only been about eight years since the discovery."

Goran Hansson, chairman of the prize committee, said: "We award the discovery of a fundamental principle. "That principle has already been proven by scientists around the world. It has been validated and the time is right to award a Nobel Prize."

RNA, or ribonucleic acid, is a molecule that works alongside DNA to transmit genetic information. The genome works by recording instructions for the manufacture of proteins in DNA, which are then conveyed to the cell’s protein-making structures using messenger RNA.

Dr Fire, 47, of Stanford University, and Dr Mello, 45, of the University of Massachusetts, discovered that double strands of RNA can block messenger RNA from specific genes, silencing the genetic information they carry and stopping protein production.

Clinical trials of RNAi therapies are now under way for diseases including macular degeneration, a common cause of age-related blindness, and chronic lymphocytic leukaemia.

Sir John Sulston, former Director of the Wellcome Trust Sanger Institute near Cambridge, who won the Nobel Prize for Medicine in 2002 for his work on the nematode worm Caenorhabditis elegans, said the award was richly deserved. He found it particularly pleasing as the pair’s key experiments were conducted using C. elegans as a model organism.

"I am absolutely delighted at the news of this incredibly well-deserved prize," he said. "On a personal note, I have known both for a long time – in Andy’s case, since he was a visitor to the MRC Laboratory of Molecular Biology in Cambridge.

"From the beginning, they have been consistently developing methods to introduce nucleic acids into organisms, starting with DNA and then going on to exploring the mechanisms by which RNA can modulate gene activity."

Julie Ahringer of the Gurdon Institute at the University of Cambridge said: "I can’t underestimate impact of RNAi — it has really revolutionised biological research, allowing scientists to quickly assess the function of genes in all animals, from worms to humans. It also has significant therapeutic potential through its use in turning off disease causing genes."

Professor Chris Higgins, Director of the Medical Research Council Clinical Sciences Centre, in London said: "The discovery of RNA-mediated gene silencing has revolutionised our understanding of the control of gene expression and development. Perhaps even more importantly, it provides a simple tool for manipulating gene expression in the laboratory, and with great promise for altering gene expression to treat diseases such as viral infections and cancer."

Explore World News

• World Agenda

• Iraq News

• US & Americas News

• Europe News

• Middle East News

• Asia News

• Africa News

• Ireland News

Times Recommends

• The Japanese Prime Minister is doomed: or is he?
• Brighton company 'involved in cyber attack'
• The art of survival: it's all in the mind