Brussels, 23 Jul 2003

With China and Taiwan now officially off the list of areas with recent local transmission of SARS, the chain of transmission of this new disease appears to be broken globally, according to the WHO. But how much do we know about its lifecycle?

A team of scientists has made a breakthrough in describing how the severe acute respiratory syndrome, or SARS, virus makes several of the materials necessary for replicating itself. This comes less than six months after the virus' first reported victims in South East Asia and later Canada.

Researchers from two German and one Dutch university have identified which materials are produced by the SARS coronavirus inside infected cells. Their findings will appear in the Journal of General Virology under the title 'Mechanisms and enzymes involved in SARS coronavirus genome expression'. They indicate that nucleic acids and proteins are the culprits causing copies of the virus to made, what the scientists call 'viral replication'. "It is essential, when you are looking for ways to stop a disease, that you know exactly how viruses make copies of themselves and spread," explained Dr John Ziebuhr from the University of Wurzburg, one of the three research teams. "Now that we know the properties of some of the proteins necessary for viral replication, we can discover ways to stop it, and prevent it from spreading," he added.

Fast-track research for a fast-spreading virus

SARS is a life-threatening form of pneumonia. In the course of a few months, an epidemic emerged that spread like wildfire from its likely origin in Guangdong Province, China, to some 32 countries. Today, it is known to be caused by a new coronavirus, or SARS CoV. Coronaviruses have the largest RNA genome, and their lifecycle inside host cells differs in several ways from all other RNA viruses. Humans, livestock and animals can contract CoVs, which cause diseases of the respiratory tract and intestines.

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Now, the scientists are looking for ways to curb viral replication by stopping the essential proteins from working properly. They have found that one essential protein in particular, called coronavirus main proteinase, is almost identical in every coronavirus studied so far, including SARS CoV.

This fact alone should fast-track the research process, allowing the European research teams to use existing information about the structure of other coronaviruses' main proteinases to design inhibitors specifically for SARS CoV main proteinase.

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By the end of June 2003, the World Health Organisation (WHO) had reported about 8 400 cases and 800 deaths from SARS. The rapid spread of the disease and the high number of deaths makes it a global threat for which no effective treatment is currently available, reports the Society of General Microbiology, which disseminates current research findings in microbiology. But Dr Ziebuhr notes that this recent discovery could lead to the development of effective anti-SARS drugs.

DG Research
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