Originally Published IVD Technology
May 2003
INDUSTRY NEWS
Labs join forces to develop diagnostics for SARS |
| Coronaviruses have a halo- or crown-like appearance. |
A global collaboration among a group of laboratories has succeeded in developing diagnostic tests that could help prevent the spread of a potentially fatal epidemic. The outbreak of severe acute respiratory syndrome (SARS) has caused widespread panic around the world. As of April 18, 2003, according to the World Health Organization (WHO; Geneva), a total of 3461 SARS cases, including 170 deaths, had been reported in 27 countries. As of that date, 208 cases had been reported in the United States, but no deaths.
In response to this epidemic, WHO established a network of 11 laboratories in nine countries. This collaborative multicenter research project was devoted to finding and developing diagnostic tests for SARS.
Since the initiation of this project, one of the network laboratories has developed a simple and rapid noninvasive diagnostic test for SARS. Microbiologists at the University of Hong Kong developed a real-time quantitative polymerase chain reaction (PCR) assay that can detect the presence of the SARS virus in nasal swabs and throat cultures. Results from this test can be available in 3–4 hours.
In March, after identifying the coronavirus found in SARS patients, the University of Hong Kong team developed a diagnostic test for the presence of the virus’ RNA. To aid in arresting the spread of SARS, which epidemiological data suggest is spread readily through droplet transmission, the Hong Kong team concentrated on developing a way to identify more rapidly the virus in SARS patients.
The new test they developed is often positive early in the disease, before any antibody response can be detected. Because the testing of hundreds of suspected SARS cases may be needed daily during an outbreak, the team is also adapting this test to a high-throughput format. It is expected that the rapid method of prompt identification of this pathogen will help control the disease and facilitate prompt and appropriate patient treatment.
Other potential diagnostic tests for SARS are also being developed. One such test that has demonstrated promise uses the immunofluorescence assay (IFA) technique. IFAs detect antibodies in the serum of SARS patients after about day 10 of illness onset. This is a reliable test requiring the use of a fixed SARS virus, an immunofluorescence microscope, and an experienced microscopist. Positive antibody tests have been shown to indicate that a patient was infected with the SARS virus.
WHO officials have expressed optimism that the diagnostic tests that have been and are being developed will be effective in diagnosing for SARS.
“The PCR test is already showing good reliability in detecting SARS cases in the early days of infection,” said WHO officials. “The IFA test is being used to detect infection in convalescent sera at about three weeks after infection begins. Together, the two tests should help to quickly and safely reassure the many patients the world over who are concerned about suspicious symptoms and yet may be suffering from common illnesses at home.
“Samples from hundreds of confirmed and suspected SARS cases will be tested using these new diagnostic tools,” added WHO officials. “In so doing, the tools will get further refined and streamlined to upgrade their capacity for daily screening of large numbers of samples.”
Additional information about SARS can be accessed via WHO’s Web site at http://www.who.int
and CDC’s Web site at http://www.cdc.gov.
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