Chinese scientists announced a breakthrough yesterday in decoding the evolutionary pattern of the coronavirus, which caused the worldwide SARS outbreak last year.

Zhao Guoping, a noted researcher from the China National Human Genome Research Institute, said here yesterday that an eight-month extensive study of the SARS (severe acute respiratory syndrome) coronavirus in southern China revealed patterns in various phases of the virus evolution.

Molecular analysis of virus isolated from SARS patients in Guangdong Province and the Hong Kong Special Administrative Region demonstrated the initial phase of the epidemic was characterized by quick amino acid changes in the virus and relatively low infectivity.

The middle phase of virus evolution was marked by the "super- spreader case" and a slower amino acid substitution rate and high infectivity. The last phase of the epidemic saw a relatively stable virus genome structure.

The study also indicated the mutation rate of the coronavirus is a third of that of the AIDS virus.

Scientists analyzed the genetic coding of 18 virus samples isolated from 24 SARS patients in Guangdong and Hong Kong and 11 coronavirus-infected biological samples.

After comparing the genetic coding with those of the existing 32 human SARS coronavirus and two coronavirus of civet cats, scientists had a clearer understanding of the molecular mutational patterns of SARS, shedding light on pre-emptive control strategies and the development of therapies and vaccines for the virus, according to experts.

(China Daily January 31, 2004)