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Last Updated

17 May 2003

Source: The Lancet 361(9370), May 17, 2003


Coronavirus confirmed as cause of SARS

An international team of researchers has completed the final proofs that severe acute respiratory syndrome (SARS) is caused by the primary suspect--SARS-associated coronavirus (SCV). Health officials hope that the confirmation will make the task of containing the epidemic more manageable.

Tests done over the past 2 months have shown that SARS-associated coronavirus fulfils three of Koch's six postulates that must be satisfied to establish a virus as the cause of a disease: isolation from the host, cultivation in host cells, and filterability.

New research has shown that the virus fulfills the three remaining criteria: production of similar disease in the host species or a closely related species--in this case macaques; reisolation of the virus from infected test individuals; and detection of an immune response to infection with the virus (Nature 2003; 423: 240).

Lead researcher Albert Osterhaus (Erasmus Medical Centre, Rotterdam, Netherlands) said that the confirmation of the role of the virus was a tremendous collaborative effort. "Confirmation of the causative role of SCV in the macaque experiment came within 3 weeks after the virus had first been found and implicated as the possible cause of SARS", he said. "This rapid turnaround was made possible by the exemplary coordination of all the scientific efforts through the WHO network of laboratories involved."

Trish Perl (Johns Hopkins School of Medicine, Baltimore, MD, USA) compared the speed with which SCV was confirmed as the cause of SARS to the time it took to confirm HIV as the cause of AIDS--nearly 2 years in the latter case. "The rapidity of discovery, identification and fulfillment of Koch's [postulates] is astonishing", said Perl.

The confirmation of SCV's role in SARS will have a substantial effect on efforts to control the disease, said Alison Galvani (University of California, Berkeley, CA, USA). "The identification and genetic sequencing of the causative agent of SARS does have implications for the control of this disease both in the short term and in the long term", she said. "The PCR assay can be used as a diagnostic test to identify people who are incubating the disease but are not yet symptomatic. This will enable us to develop much more efficient quarantine procedures of only the people who have been infected, rather than everyone who may have been exposed."

David Lawrence