Artikel
Laboratory diagnosis for SARS: an overview
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Veröffentlicht: | 26. Mai 2004 |
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Gliederung
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There are three technical approaches to diagnose SARS-CoV infection. Virus isolation can be accomplished by a widely available cell line (Vero), and with obvious cytopathic effects develop within 2-4 days. However, virus isolation lacks sensitivity particularly for stool samples. Recently, a human colonic cell line was also found to be susceptible. Although this may serve as a better in-vitro model, the absence of cytopathic effect makes it less ideal for routine diagnostics. Direct detection of viral RNA requires less strengthen laboratory containment facilities, results available within 1-2 days, and is more sensitive. Conventional reverse-transcription PCR and real-time PCR have been successfully applied in the previous outbreak. Serology remains a useful tool, as it does not have the problem of insensitive as for virus isolation, or cross-contamination as for PCR; and is the only means for retrospective diagnosis. At present, neutralization test is regarded as the gold standard, and immunofluorescence test has proved to be accurate. Western blot assay also has a potential, but the interpretation remains to be established. A number of viral lysate- and synthetic peptide-based assays for IgG detection are now commercially available. In general, these IgG assays are relatively less sensitive and specific. These assays are more appropriate as a screening test for large-scale epidemiological studies, rather than for individual patient diagnosis. In this talk, the performance of different diagnostic assays with reference to specimen type, time course of infection, and different clinical situations will be presented. Newer developments in SARS diagnostics will be discussed.