Proof that a newly identified coronavirus, severe acute respiratory syndrome coronavirus (SARS–CoV) is the primary cause of severe acute respiratory syndrome (SARS) came from a series of studies on experimentally infected cynomolgus macaques (Macaca fascicularis). SARS–CoV–infected macaques developed a disease comparable to SARS in humans; the virus was re–isolated from these animals and they developed SARS–CoV–specific antibodies. This completed the fulfilment of Koch's postulates, as modified by Rivers for viral diseases, for SARS–CoV as the aetiological agent of SARS. Besides the macaque model, a ferret and a cat model for SARS–CoV were also developed. These animal models allow comparative pathogenesis studies for SARS–CoV infections and testing of different intervention strategies. The first of these studies has shown that pegylated interferon–α, a drug approved for human use, limits SARS–CoV replication and lung damage in experimentally infected macaques.
Finally, we argue that, given the worldwide nature of the socio–economic changes that have predisposed for the emergence of SARS and avian influenza in Southeast Asia, such changes herald the beginning of a global trend for which we are ill prepared.