Bioscope '03
by Dr. Barbara Price

Severe Acute Respiratory Syndrome, SARS

          "One should bear in mind, however, that in the past, viruses have been initially isolated from patients with a specific disease but subsequent investigations revealed no actual association at all." --- from "Identification of a Novel Coronavirus in Patients with Severe Acute Respiratory Syndrome", Drosten, C, et al., NEJM, April 10, 2003. With that in mind, two papers in the NEJM on the web April 10, 2003 describe different approaches that identify a new coronavirus, which may be responsible for SARS. Using specimens collected from patients suspected to have SARS, the two studies are very complimentary. Both studies concentrated on the respiratory route for the infection, and results are consistent with infections in the respiratory tract, but do not eliminate SARS virus replication outside the respiratory tract. In the first article, by Drosten cited above, samples from 18 patients were collected. The highest levels of viral RNA, indicating millions of viral particles, were found in the sputum of patients and were present early in the infection. Later in the infection, the bronchoalveolar lavage of one patient also contained almost a million viral particles. This group was able to develop a reverse-transcriptase-PCR test that was positive for those patients that had SARS. This RT-PCR test will be donated free to laboratories for evaluation beginning on April 14, 2003. In the second paper, "A Novel Coronavirus Associated with Severe Acute Respiratory Syndrome Ksiazek, T. G, et al., use a combination of PCR, antibody testing, and electron microscopy on samples from a larger number of patients. The researchers also took samples from the nose, throat, sputum, and in some cases, from bronchoalveolar lavage, kidneys and lungs. Not all the tests were consistent, but overall those patients who had been diagnosed with SARS had positive results on at least one of the tests. Both studies indicate that the coronavirus is related to a number of viruses, and its closest relative may be the avian infectious bronchitis and turkey coronavirus. Thus, SARS may be have been caused by an avian virus that jumped species to infect humans.
          The identification of the probable virus causing SARS really occurred very quickly and attests to the cooperation of scientists in many laboratories. From samples from patients in early March to identification of a likely cause only took one month. Imagine if China had been more forthcoming with information in November, perhaps those recent victims might not have died. Close collaboration and disease surveillance can only help public health worldwide.