They hope that such technology will dramatically cut the time it takes to get a medicine on the market by removing the need for clinical trials over many years.

One company has already built a virtual heart that has been used in studies of irregular heartbeats and to test a new medicine.

Their next step is to create a virtual immune system.

Mathematical model

The project is being led by Physiome Sciences, the US company behind the virtual heart, and PA Consulting, a London-based consultancy.

Physiome's virtual heart used mathematical equations to simulate the biochemical, electrical and mechanical operation of the heart, and has proved a useful tool in research.

Bill Scott, chief executive of Physiome, said: "The immune system is the main line of defence for the body and therefore a vital area for us to understand if we are to find more effective treatments for arthritis, autoimmune disorders, inflammatory diseases and more."

Autoimmune diseases are caused by the body attacking itself - immune cells think the body's own tissue is foreign and seek to eradicate it.

Working in a new medium

Medical research traditionally takes place in one of two environments - in vivo - on living organisms - or in vitro - in test tubes.

The move towards conducting research on a computer - or in silico - will reduce the development time of new medicines because at the moment new products have to undergo various trials before a government will approve them.

A virtual human heart has shown promise

The Pharmaceutical Research and Manufacturers of America, a trade group representing US drug companies says it take an average of 15 years and $500m for a new medicine to get on the market.

But with a complete model of the human body, doctors would have a good idea of what a drug was going to do without the need for expensive large-scale trials on animal and human guinea pigs.

The scientific community is working together to achieve the goal of a complete mathematical model of the body - the human physiome.

Just as there is a Human Genome Project working to draw up a complete map of human genetics, so there is a Human Physiome Project looking at the physiological dynamics of the body.

Change of direction

While Physiome Sciences - a commercial company - has previously worked on biological applications, PA Consulting's previous work has centred on developing computerised business models.

It believes its experience in dealing with complex networks involving cause-and-effect relationships will help in the development the virtual body.

The company is investing £3m in Physiome, which will also acquire PA's subsidiary company Organ Systems Modelling.

Physiome chairman Jeremy Levin said the company intended to see the ambitious project through.