A New Quantum Dot-Based Lateral Flow Immunoassay for the Rapid Detection of Influenza Viruses

Rapid and accurate diagnosis of influenza is crucial to contain influenza virus outbreaks. In clinical settings, lateral flow immunoassays (LFIAs) are widely used for rapid influenza antigen detection. The choice of label plays an important role in determining the sensitivity of the LFIA. Quantum dots are one of the most promising fluorescent reporters. Here, we evaluated a novel quantum dot-based assay, QuantumPACK Easy Influenza A + B (QuantumPACK Easy; BioSquare Inc., Korea). A total of 394 nasopharyngeal swab samples, including 94 influenza A virus-positive, 98 influenza B virus-positive, 175 influenza A and B virus-negative, and 27 other respiratory pathogen-positive samples, were collected. Samples were tested with QuantumPACK Easy, Allplex RP real-time RT-PCR assay (Allplex RP; Seegene, Korea), and Sofia Influenza A + B FIA (Sofia; Quidel, CA, USA). The sensitivity and specificity of QuantumPACK Easy was analyzed using the Allplex RP assay. The agreement between QuantumPACK Easy and Sofia assays was also analyzed. The sensitivity of QuantumPACK Easy for influenza A and B was 80.9% and 83.7%, respectively. The specificity of QuantumPACK Easy was 100%. Cross-reactivity with other respiratory pathogens was not observed. Total agreement between QuantumPACK Easy and Sofia was 89.6% (kappa 0.783). The sensitivity of the Sofia assay was 66.0% for influenza A virus and 61.2% for influenza B virus. QuantumPACK Easy had acceptable performance, with better sensitivity than a commercially available antigen detection assay, possibly due to the characteristics of the quantum dot.