SARS Virus Identified

Medical Author: Frederick Hecht, M.D.
Medical Editors: Barbara K. Hecht, Ph.D. and Leslie J. Schoenfield, M.D., Ph.D.

The virus of SARS (severe acute respiratory syndrome) has been identified, according to two reports released online by The New England Journal of Medicine (April 10, 2003). It turns out that the SARS virus is a novel coronavirus.

One of the reports in The New England Journal of Medicine is first-authored by Thomas G. Ksiazek from the Center for Disease Control (CDC) in Atlanta. The other report is first-authored by Christian Drosten from Hamburg, Germany.

Ksiazek Report: Specimens from patients in 6 countries were tested using virus isolation techniques, an electron microscope, and other tools to try to identify the virus. Electron microscopy revealed features characteristic of coronaviruses. A very sensitive molecular method called reverse transcription-polymerase chain reaction (RT-PCR) was also used. This technique revealed a chemical (nucleotide) sequence of DNA that clearly identified a unique coronavirus. In fact, this virus is only distantly related to other known coronaviruses. For the decisive test, specific RT-PCR segments of DNA (primers) were used to identify identical nucleotide sequences in 12 other SARS patients from several locations. This finding is consistent with a point source outbreak; that is, with an outbreak that began in a single location. Furthermore, it appears that this virus may never before have infected the US population.

Drosten Report: Clinical specimens of patients with SARS were searched for unknown viruses by using cell cultures and molecular techniques. A novel coronavirus was isolated in cell culture, and a sequence 300 nucleotides in length was obtained by the polymerase chain reaction (PCR). Genetic characterization indicated that the virus, as the Ksiazek group also reported, is only distantly related to known coronaviruses. The virus was present in high levels in sputum. Accordingly, tests of sputum should reveal the virus in SARS patients, although nasal and throat swabs may not pick it up. These investigators also found that the virus can be shed in feces. Appropriate precautions, therefore, need to be taken to avoid spread (transmission) by both the respiratory and fecal routes.

Our Comments: Both reports involve a large number of researchers and reflect an epochal research project carried out in record time. The Ksiazek Report lists 26 co-authors from many parts of the world "on behalf of the SARS Working Group." The Drosten Report also list 26 co-authors and emanates from not only Germany but also France and The Netherlands. The discovery of this novel coronavirus has been the result of international cooperation at its best.

The name Urbani SARS-associated coronavirus has been proposed for this new virus, as a tribute to Dr. Carlo Urban. Director of Infectious Diseases for the Western Pacific region of the World Health Organization, he was the first person to recognize the SARS epidemic. He courageously cared for many patients in Vietnam with SARS and tragically died of it. He was 46.