Researchers are once again tapping the power of the public's computers, this time to search for anti-smallpox compounds, with new downloadable screensaver programs. The Smallpox Protection Project, which debuted today, was created by an international consortium of companies and universities to analyze 35 million potential drug molecules by marshaling the idle processing time of more than two million participating computers worldwide.

Together, these computers represent a virtual supercomputer with peak computing power of more than 1,100 teraflops—more than 30 times the power of today's fastest supercomputer at the Earth Simulator Center in Japan. Results from individual computers are returned via the Internet to United Devices' data center for analysis, and results will be delivered to the US Department of Defense.

Project organizers hope this collective processing power will allow them to finish decades' worth of work in a month or two. "The largest supercomputer in the world has some 2,000 processors. Now those are pretty good processors, but 2,000 is nowhere near two million," said participating computational chemist Karl Harrison of the University of Oxford.

This distributed-computing strategy has already been used to search for potential drugs against cancer and anthrax as well as for extraterrestrial intelligence.

The smallpox project will be testing all chemicals which are known to be suitable for ingestion and readily available for synthesis. Each molecule will be tested five times against three regions on three versions of the enzyme type I topoisomerase, one viral version and two human. This protein uncoils DNA from the supercoiled form the smallpox virus uses during transport. By attacking this protein, the project hopes to find a drug to block viral reproduction.

"Topoisomerase is a very good target for developing natural drugs," said virologist Mark Challberg of the National Institute for Allergy and Infectious Diseases. "The truth is, in the case of pox viruses, this is almost the only possible target. Only three proteins for pox virus have been solved, and this protein is clearly the best candidate for an antiviral drug of those three."

The two human versions of the enzyme are present in all cells. While the project wants to find compounds that block the viral enzyme without lethally interfering with the human versions, Harrison explained these proteins are also implicated in cancer. "We could find anticancer drugs as well," he said.

Smallpox was eliminated from the wild in 1977, but could prove a terrifying weapon if terrorists obtained illegal stocks. Just last week, President Bush proposed a $6 billion research program to find vaccines and treatments for smallpox and other potential bioweapons. There is currently no specific treatment known to fight smallpox after infection. Vaccination is only useful as a preventive measure. The smallpox vaccine is also lethal in two out of every million cases and cannot be given to individuals without fully functioning immune systems, such as young children and AIDS or organ-transplant patients.