Comparison of Diagnostic Tests for Detection of Nonstructural-1(NS1) Antigen Dengue virus using Immunochromatography and Fluorescence Immunoassay Methods

Background: NS1 is currently widely used for diagnosis of dengue virus (DENV) infection. Various methods are used to diagnose DENV infection (DVI), either ELISA, immunochromatography (ICT) or most recently the fluorescence immunoassay (FIA) method which are commercially available. Objective: This study aimed to compare the detection capabilities of dengue NS1 antigens using (1) Dengue NS1 ICT Ag (Standard Q-SD Biosensor, Inc.), (2) Dengue NS1 ICT Ag (SD Bioline-Standard Diagnostic, Inc), and (3) Dengue NS1 Ag FIA (Standard F-SD Biosensor, Inc.) Methods: This study consisted of serum samples (n=80) with the number of DVI patients (n=50), non-DVI (n=30). All samples were examined using all three commercial kits for NS1 antigen testing. All DVI samples showed results of reverse-transcriptase polymerase chain reaction (RT-PCR-SIMPLEXAᵀᴹ Dengue-Focus Diagnostics) and/or positive dengue NS1 (Panbio® Dengue Early ELISA) antigen. Results: Standard F showed the highest sensitivity (82%) compared to Standard Q (74%) and SD Bio line (74%). These three commercial kits had the same specificity 100%. The positive predictive value all of these kits was 100% each. The negative prediction value of Standard F, Standard Q, and SD Bio line were 76.9%, 63.8%, 63.8%, respectively. These three NS1 antigen tests had a good agreement (κ 0.681-0.774). Conclusions: FIA test performance (Standard F SD-Biosensor, Inc.) were a quick and easy examination, showing a higher sensitivity and specificity than ICT for detecting DENV infection. Further research is needed to confirm the diagnosis of primary or secondary infection.