Three Emerging Coronaviruses in Two Decades

In the past two decades, the world has seen three coronaviruses emerge and cause outbreaks that have caused considerable global health consternation Coronaviruses are enveloped, nonsegmented, single-stranded, positive-sense RNA viruses that have a characteristic appearance on electron microscopy negative staining Image 1 As a matter of fact, the characteristic electron microscopy appearance was the clue to amplify and sequence nucleic acids from Dr Urbani’s (one of the health care providers who died of severe acute respiratory syndrome [SARS] in 2003) respiratory specimen using a consensus coronavirus primer 1 The sequence of the virus was significantly different from other coronaviruses known to cause human…