Study Points to Possible SARS Drugs

Virus has Achilles' heel like that of some cold-causing germs

TUESDAY, May 13, 2003 (HealthDayNews) -- An experimental drug that fights the common cold could, with some tweaking, be effective against the SARS virus, a new study suggests.

German researchers say an important enzyme in the SARS pathogen is similar in structure and function to one found in cold-causing rhinoviruses. The enzyme, known as a protease, is critical to replication. Drugs that block the action of proteases are used to control infection with the AIDS virus.

One such drug has shown promise in clinical trials at controlling cold symptoms by inhibiting the protease in rhinoviruses like that in the SARS virus. That drug, a nasal spray called AG7088, "might be a good starting point for the development of drugs against coronavirus, including SARS coronavirus," says Rolf Hilgenfeld, a biochemist at the University of Lübeck and leader of the study.

The drug isn't a perfect match for the SARS enzyme, Hilgenfeld says, so it most likely won't be used to treat patients with the disease. However, the compound could lead scientists to the right therapy.

"If you manage to block this enzyme you will also block replication" of the virus, says John Ziebuhr, a virologist at the University of Würzburg, a co-author of the study. Hilgenfeld and Ziebuhr spoke to reporters Tuesday on a teleconference hosted by the journal Science, which published their study online.

SARS, short for severe acute respiratory syndrome, has been linked to at least 577 deaths, mostly in Asia. The infection is especially dangerous in older people. Scientists have identified the virus as a new member of the coronavirus family, microbes that have until now been thought to cause only mild illness in humans.

Agouron Pharmaceuticals, Inc., a biotechnology firm in San Diego, Calif., and a unit of Pfizer Inc., makes AG7088. The drug is currently in clinical trials and "is proven safe," Hilgenfeld says.

Hilgenfeld says altering AG7088 to improve its fit with the SARS protease could take as little as "a few months."

Even so, the researchers say their work won't help patients in the current SARS outbreak, and it probably will be several years before a drug built on the latest discovery comes to market. With HIV, scientists identified proteases in the microbe in 1988, and the first protease inhibitors arrived in the mid-1990s. Drug development is more sophisticated now than then, Hilgenfeld adds, so the process could be quicker.

Officials at Pfizer could not be reached immediately for comment.

More information

For more on SARS, visit the World Health Organization. For more on the common cold, try the National Institute of Allergy and Infectious Diseases.

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