Will serious genetic variations of SARS virus occur in the body of SARS patients? Will the formation of these variants and the genetic variations affect course of disease and treatment?

A study team led by Professor Wang Fusheng from the 302 Hospital of PLA (People's Liberation Army of China) first discovered formation features of quasispecies within SARS patients and law of variations of related genes. The result of their study was published respectively on the New England Medical Journal and Emerging Infectious Disease Journal, marking a world-class achievement made by Chinese scientists in the field of SARS research.

As introduced different strains of a same virus could exist simultaneously in an infected body, all these strains are jointly called quasispecies. As an important study object in virus-caused infectious diseases, quasispecies affect the occurrence, development and result of a disease, and at the same time is directly related with diagnosis, treatment and the development of a preventive vaccine.

During the SARS outbreak last year, the research team colleted samples from the first batch of Beijing's SARS patients received by the hospital, and adopting advanced genetic cloning and biological information techniques to analyze isolated SARS virus genes. They found out that there existed more than 110 variant loci on the S gene of SARS virus, of which 9 important ones were first reported internationally. The discovery of different variants in a same patient revealed the existence of SARS quasispecies and related features. The study showed that the frequency of SARS virus variation is lower than that of hepatitis C and HIV, this may be related to the fact that SARS virus only causes acute infection.

The study could help clinical doctors to understand SARS virus deeper and is of great value for guiding vaccine development, experts said.

(People's Daily May 11, 2004)