Study on laboratory diagnostic method for determination of SARS patients in Jiangsu province

Objective:To establish pathogenic detection methods of Severe Acute Resqiratory Syndrome(SARS) and to provide a basis for diagnose and field prevention and control for SARS.Methods: Detection of the nucleic acid of SARS-CoV by RT-Nested-PCR and real-time PCR;detection of the IgM antibody to SARS-CoV by ELISA;the specimens which have shown PCR or ELISA positive result were observed for SARS-CoV by electronic microscope;detection of the nucleic acid of Coronavirus by PCR using genus-specific degenerate primers.For differential diagnose,IgM antibodies to nine frequent pathogens of respiratory such as mycoplasma pneumoniae and etc.were tested by IFA,the nucleic acid of Influenza A or B,and Legionella pneumophila were examined by PCR amplification. Results: There were total of 506 clinical samples were detected.In 2003,7 SARS cases were reported with clinical diagnose,5 of which were positive with laboratory detection;in 132 samples of different types,8 positives were detected by using RT-Nested-PCR.Four PCR products(108bp) of the positives were sequenced and compared with SARS-CoV in the GenBank by using BLAST server,it showed 100% homology.Three of 30 clinical samples in different types and 4 of 101 serum samples were found to be positive by real-time PCR and ELISA,respectively.SARS-Cov-like particles were observed in different type clinical samples in three SARS cases.There are 75 serum samples were detected for IgM antibody against 9 respiratory pathogens respectively by IFA.The results showed that 9 were positive to Legionella pneumonia,11 were to Influenza B,2 were to both Legionella pneumonia and Influenza B,and the rest were negative.Twenty-one samples from patients who have unknown cause of fever disease were detected by Coronavirus-specific PCR using degenerate primers and 2 throat swabs were found positive.Fifteen throat-washing samples and 15 urine samples were detected for Legionella pneumonia, and 25 throat-washing samples were detected for Influenza A and B,the results were all negative.Conclusion: The detective result using the methods above mentioned has quite accordant with that of clinical diagnosis and PCR method has high specificity for SARS-CoV.