Objectives To evaluate potential application of serum detections of dengue virus (DENV) nonstructural 1 antigen (NS1), viral RNA, and immunoglobulin M (IgM) antibody in early laboratory diagnosis of dengue virus infection.
Methods Totally 432 serum specimens were collected consecutively from June to November 2014 from patients clinically suspected with dengue fever in Guangdong province, China. All the specimens were simultaneously detected for NS1 with flow immune chromatographic rapid diagnosis test (RDT) and enzyme-linked immunosorbent assay with (ELISA), viral RNA with real time quantitative polymerase chain reaction (qRT-PCR), and DENV IgM/IgG antibody with ELISA.
Results Of all the specimens, 361 (83.6%) were positive for one of or more of the three indicators and the indicator with the highest positive rate was DENV NS1 (358, 82.9%), followed by viral RNA (268, 74.3%) and IgM antibody (179, 49.5%). For the all positive specimens, 87.8% (317) and 11.9% (43) were collected from primary and secondary dengue fever patients. For the specimens collected from dengue fever patients in acute or late acute phase, the positive rate of DENV NS1 RDT (97.0%) and ELIZA (98.6%) were significantly higher than that of viral RNA qRT-PCR (88.9%) and IgM antibody ELISA (59.3%) (both P < 0.01). The results of DENV NS1 detection with RDT and ELISA were significantly consistent (κ = 0.363, P < 0.001). For the specimens collected from acute phase patients, the positive rate of viral RNA detection with qRT-PCR was significantly higher than that of IgM antibody detection with ELISA (P < 0.01).
Conclusion The study results suggest that DENV NS1 antigen detection is highly sensitive in diagnosis of primary dengue fever patients in non-endemic regions; DENV RNA test is of significance in early diagnosis of dengue fever; while, DENV IgM antibody detection is a suitable test for auxiliary diagnosis of dengue fever at or after the 5th day of the incidence.
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