Three years have passed since the global outbreak of severe acute respiratory syndrome (SARS). During this time, major progress has been made in understanding the mechanisms of infection [1]. Three-dimensional structures have been determined for a number of non-structural and structural proteins of the virus and of related coronaviruses [2-5]. In the absence of a crystal structure for the viral RNA polymerase, the main proteinase remains the most suitable anti-coronaviral drug target [3, [6]

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... [8] [9] [10] . Progress in designing and synthesizing specific inhibitors for this enzyme will be reported.