Revolution in science: a genetic discovery to change the world

A revolutionary development in genetics has raised the prospect of curing cancer and treating lethal viral infections using a technique discovered by scientists during a series of pioneering experiments.

Researchers are already comparing the findings to the earliest days in the development of antibiotics, which radically altered the way doctors treated bacterial diseases in the late 20th century.

Studies in the US and Europe last month showed that the use of the technique made human cells in the test tube immune to the effects of polio virus and HIV. Researchers believe it will also work against cancer and could even help to overcome tissue rejection in transplant operations.

Gordon Carmichael, professor of microbiology at the University of Connecticut in Farmington, who is a scientific adviser to the journal Nature, said the process, known as RNA interference (RNAi), had astonished scientists with its power to overwhelm viruses and cancers by turning off or "silencing" harmful genes.

"In biology in the past 12 to 18 months there's been a revolution. It's even changing the way we're designing experiments," Professor Carmichael said. "We've been trying to turn off the genes of viruses and cancer cells for years. This works. It's proving to be a whole new approach to anti-cancer and anti-viral treatment."

Scientists emphasise that the technique is still in its infancy and that it will be at least two years before the first clinical trials in humans can go ahead. However, they are also optimistic that it will prove highly effective yet with none of the side-effects of more conventional treatments.

Biotechnology firms are vying for patent rights and pumping millions of dollars into the development of the technique. One team of scientists received $15m (£11m) last week to develop a treatment for hepatitis and cancer.

The story of the discovery dates back to 1990, but the real breakthrough occurred in 1998, when Andrew Fire, at the Carnegie Institution, affiliated to the Johns Hopkins University in Baltimore, found that RNA – a close cousin of DNA, the molecule of inheritance – could switch off genes.

Dr Fire coined the phrase "RNA interference" and explained it by suggesting that genes can be selectively silenced. That would mean defective genes that cause tumours, or genes necessary for a virus to replicate in a cell, could be turned off.

But the real breakthrough occurred in experiments this year which involved testing the idea on human cells – Dr Fire had shown it only on a microscope nematode worm. Two independent teams of researchers demonstrated that human cells in a test tube could be made to resist infection with HIV, and a third set of researchers found that it worked against the polio virus – in a way that they believe will prove effective against other human viruses.

"In the past year we've realised that this machinery of RNA interference works just as well in human cells. It's led to an explosion in interest," Professor Carmichael said.

Five years ago there were just a handful of scientific papers published on RNAi, two years ago there were 100, last year there were 1,000 and this year there will be thousands more, he said.

One idea for Aids treatment is to take out a person's blood cells and engineer them using RNAi to make them immune to HIV. The patient should then be resistant to infection.

The beauty of the process is that it is specific to the gene being targeted and so the interference should not result in the silencing of other important genes, Professor Carmichael said. This is important when it comes to possible side-effects. "If you design it against HIV then there is almost no possibility that it will result in a perfect match against the patient's own DNA," he said.

One significant problem that still needs to be addressed, however, is how to ensure that all a patient's cells that need to be treated with RNAi actually undergo the process. "It's a problem of delivery – how to get the active ingredients to the cells that need them," the professor said.

Several teams of scientists are working on the problem and experiments on mice indicate that it RNAi treatment will be easier on organs that have a rich blood supply such as the liver and the kidneys. Despite the difficulties that remain, the power of the technique has astonished scientists.

"Once we learnt the rules they turned out to be far simpler than we thought. It could be a powerful way of attacking viruses and cancer. It's a revolution," said Professor Carmichael.

Dr Fire said that there was great excitement in the scientific community about the potential of RNAi. At the very least, he said, it would explode our understanding of the human genome.

Richard Henderson, the director of the Medical Research Council's Laboratory of Molecular Biology in Cambridge, said that he is already budgeting for an explosion in interest in the RNAi technique. "It opens up a fantastic number of possibilities. It's a way of carrying out a very quick scan of the the genes."