Scientists announced a possible breakthrough in the treatment of severe acute respiratory syndrome (SARS) on Friday.

According to their report in Guangzhou, South China's Guangdong Province, small interfering Ribonucleic Acid (siRNA), able to target specific genes, is showing efficiency in combating the disease.

SARS, first recognized in 2002, killed 774 people worldwide before it was brought under control by quarantine, isolating patients and restricting travel.

Since then, researchers led by Zhong Nanshan, director of the Guangzhou Institute of Respiratory Diseases, have been working to find drugs and vaccines to prevent another outbreak.

Researchers tested two types of siRNA that target different parts of the genome of the SARS virus.

Tests on monkeys showed that, although animals treated with the siRNA could still be infected with the disease, their symptoms were significantly less severe, suffering less lung damage and smaller increases in body temperature.

"The long-term experiments show that siRNA is effective in curing SARS, and the monkey subjects showed no adverse side effects," Li Baojian, a biotechnology professor of Zhongshan University, said on Friday.

But, Zhong Nanshan added: "The technology of siRNA cannot be used clinically in the short term."

Though the theory of siRNA was discovered in 1990, it has never been used in humans, Zhong said. "We must undergo a careful and long-term test of toxicity for siRNA before it is made into drugs or a vaccine," he said. "The test needs three to five years at least."

Research into SARS since the outbreak more than two years ago, has cost more than 3 million yuan (US$370,000). Further research needs more money, Li said.

But Zhong said the research is worth the cost. He admitted SARS is fading from people's memory, "but it does not mean a new outbreak will never occur again."

Patrick Lu, vice-president of the US-based Intradigm Corporation, said: "The discovery of the new effect of siRNA is a great contribution to the circle of worldwide medicine."

The research is sponsored by the Department of Science and Technology of Guangdong Province and the Department of Education of Guangdong Province.

About 85 per cent of the experiments are done in Guangzhou. Zhong said it is a milestone in the history of Guangzhou's science and technology development.

(China Daily August 27, 2005)