Clinical evaluation of real-time PCR assays for rapid diagnosis of SARS coronavirus during outbreak and post-epidemic periods

J Clin Virol. 2005 May;33(1):19-24. doi: 10.1016/j.jcv.2004.09.029.

Abstract

Background: The protocols of WHO network laboratories facilitated development of rapid diagnosis for SARS coronavirus (CoV) using reverse transcription (RT)-PCR assays. However, several reports have shown that conventional and real-time PCR assays were very specific for SARS CoV but lack sensitivity depending on the assay, specimen, and time course of disease.

Objective: To evaluate an automatic nucleic acid extraction system and two standardized real-time PCR assays for rapid diagnosis of SARS CoV during outbreak and post-epidemic periods in Hong Kong.

Study design: Specimens from clinically suspected SARS patients collected during outbreak and post-epidemic periods were tested by an automatic nucleic acid extraction system followed by our first generation conventional RT-PCR and two standardized real-time PCR assays (Artus GmbH, Germany and Roche Diagnostics, Germany). Paired serum samples were assayed for increasing titer against SARS CoV.

Results: In the SARS epidemic, Artus and Roche PCR assays exhibited sensitivities of 87% and 85% for respiratory specimens (n = 64), 91% and 88% for stool (n = 44), and 82% for urine (n = 29). A specificity of 100% was exhibited by both PCR assays except Artus attained only a 92% specificity for stool. For post-epidemic period, no SARS CoV was identified among 56 respiratory specimens by all PCR assays. Inhibitors to PCR assays were detected at an average rate of 7-8% among 202 clinical specimens.

Conclusion: This study highlights the high throughput and performance of automatic RNA extraction in coordination with standardized real-time PCR assays suitable for large-scale routine diagnosis in case of future SARS epidemic. As no SARS CoV was detected among specimens collected during post-epidemic period, the positive predictive value of real-time PCR assays for detection of SARS CoV during low epidemic requires further evaluation.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Disease Outbreaks*
  • Humans
  • Polymerase Chain Reaction / methods*
  • Reagent Kits, Diagnostic*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sensitivity and Specificity
  • Severe Acute Respiratory Syndrome / diagnosis*
  • Severe Acute Respiratory Syndrome / epidemiology*
  • Severe Acute Respiratory Syndrome / virology
  • Severe acute respiratory syndrome-related coronavirus / genetics
  • Severe acute respiratory syndrome-related coronavirus / isolation & purification*
  • Time Factors

Substances

  • Reagent Kits, Diagnostic