Evaluation of a novel microfluidic immuno-magnetic agglutination assay method for detection of dengue virus NS1 antigen

Background Dengue virus (DENV) is the most important arbovirus worldwide, causing infections in endemic countries and returning travellers from these areas. Rapid diagnostic tests are needed to improve patient management and monitor local transmission. The detection of DENV non-structural protein 1 (NS1) is a useful tool for the diagnosis, but the currently available methods can be time consuming or lack sensitivity. The objective of our study was to evaluate a new rapid and semi-quantitative microfluidic DENV NS1 immuno-magnetic agglutination assay based on aggregation of magnetic nanoparticles detected by an electronic reader (Virotrack Dengue Acute and Blubox, Blusense diagnostics, Copenhagen, Denmark). Methodology/Principal findings A panel of 135 serum samples from travelers returning from dengue endemic countries was analyzed (74 DENV positive samples including the four DENV serotypes, 26 Zika virus positive samples, 25 chikungunya virus positive samples, 5 malaria positive samples and 5 negative samples). Samples were tested by three different antigen detection methods: SD Dengue NS1 Ag ELISA, SD BIOLINE Dengue Duo and ViroTrack Dengue Acute. The sensitivity observed for SD Dengue NS1 Ag ELISA, ViroTrack Dengue Acute and SD BIOLINE Dengue Duo was 97.2%, 91.1% and 68.1%, respectively. All methods showed high specificity (98.4% for ViroTrack Dengue Acute and 100% for both SD Dengue NS1 Ag ELISA and SD BIOLINE Dengue Duo). SD Dengue NS1 Ag ELISA and ViroTrack Dengue Acute only failed to detect samples positive for DENV-2. Author summary Dengue virus is a human pathogen that causes millions of infections each year. It can be found in nearly all tropical areas, and people living in those regions and travelers who visit them are at risk of disease. The symptoms may vary from a mild flu-like disease to severe hemorrhagic symptoms. Accurate diagnosis of dengue is important for a better management of the disease and for epidemiological surveillance. Detection of DENV antigen is a useful tool to diagnose DENV infections. However, currently available techniques are not rapid (ELISA assays) or not accurate enough (immunochromatographic tests). Here, we evaluate a new antigen detection technique based on aggregation of magnetic nanoparticles. The method combines a short time to results (12 minutes) with a high diagnostic performance. We therefore conclude that this new technique could be a useful tool for the diagnosis of dengue.