A Study on Serum Antibodies Detection in Severe Acute Respiratory Syndrome

摘要

Context Severe Acute Respiratory Syndrome (SARS) is an emergent infectious disease that has spread to over 30 countries since November 2002. Objective To evaluate the significance of serum specific antibodies against the SARS virus in patients at different phases of the disease. Design Using Enzyme - linked Immunosorbent Assay (ELISA) and Indirect Fluorescent Antibody (IFA), serum antibodies against SARS - associated coronavirus (SARS - CoV) were analyzed from samples of SARS patients and controls. Setting Six hospitals in two major SARS affected areas in mainland China (Beijing and Inner Mongolia). Patients or Other Participants 433 probable SARS patients and 387 controls. Main Outcome Measures Sensitivity (SN), specificity (SP) , positive predictive value (PPV) , and negative predictive value (NPV) were measured . Concordance between assays was tested with Kappa test. Results The positive rate of serum antibodies with ELISA and IFA increased sharply in SARS patients symptomatic for 11 or more days. In these patients, IgM test results with ELISA and IFA were, respectively, 63.5% and 65.6% for SN, 97.9% and 100. 0% for SP, 98. 1% and 100. 0% for PPV, 62. 1% and 71. 0% for NPV; the corresponding results for IgG were 89.9% and 91.1% for SN,99.0% and 97.0% for SP,99.3% and 97.3% for PPV,85.7% and 90.1% for NPV. IgM positive rates for patients with probable SARS. Cases and controls were 42.0% and 0% ; and, for IgG, 67.7% and 0.52% . Kappa coefficients measuring agreement between IFA and ELJSA were 0.640 for IgM and 0.779 for IgG. Conclusions Antibodies against SARS - CoV in SARS patients can be detected after 10 days from the onset of the disease. The detection of serum antibodies is useful for SARS diagnosis. A good concordance between ELISA and IFA was observed.