Progress made towards Sars drug

By Helen Briggs
BBC News Online science reporter

It could take years to develop a Sars vaccine

Scientists in the US have taken a first step towards developing a specific drug to treat the Sars respiratory disease.

They have managed to find a way to stop the virus invading human cells in a test tube.

The research, published in the Proceedings of the National Academy of Sciences, could also lead to a preventative vaccine for the disease

Sars has killed 774 people and infected more than 8,000 worldwide since it emerged in southern China in 2002.

Scientists around the world are pulling out all the stops to develop the first drugs and vaccines for Sars.

Now US experts have made a discovery that could speed this process.

They have developed a synthetic human antibody - a man-made version of a protein that plays a key role in the body's immune response.

The antibody binds to the Sars virus, stopping it from entering and infecting human cells.

The researchers say it shows promise as an emergency treatment for Sars.

They hope to carry out clinical trials, in collaboration with scientists in China.

The antibody also provides a potential starting point for developing a human vaccine.

But most experts agree it will probably take years to test and manufacture such a vaccine, should one prove necessary.