Differential detection of SARS-CoV-2 variants and influenza A viruses utilizing a dual lateral flow strip based on colloidal gold-labeled monoclonal antibodies.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the seasonal influenza virus are spreading among humans concurrently, especially with the ongoing replacement of mutant strains. It is challenging to differentiate between symptoms for therapy due to the comparable symptoms following infection with the SARS-CoV-2 variants and influenza viruses. Meanwhile, in order to achieve rapid point-of-care testing (POCT) to manage the spread of the disease, we developed a dual lateral flow strip based on colloidal gold-labeled monoclonal antibodies that can perform differential detection of SARS-CoV-2 variants and influenza A viruses (IAV) in this study. High-affinity monoclonal antibodies (mAbs) targeting SARS-CoV-2 and IAV were prepared to capture antigens and labeled with colloidal gold nanoparticles (AuNPs). Based on high-affinity mAbs, two targets were immobilized on one nitrocellulose (NC) membrane to establish the lateral flow strip (LFS) for differential diagnosis of SARS-CoV-2 and IAV. With no reactivity to other viruses, this LFS is extremely specific and can only identify SARS-CoV-2 and IAV. The LFS showed a limit of detection (LOD) of 4.88 ng/mL for the Omicron BA.2 RBD protein and 2.44 ng/mL for the nucleoprotein (NP) protein of H1N1. When analyzing 16 SARS-CoV-2 positive clinical samples, eight IAV positive clinical samples, and six negative samples that had already been pre-confirmed by commercial kits, its clinical application is effectively and accurately proven. These results demonstrated that the LFS integrated with AuNPs has great potential to facilitate quick, easy, and reliable POCT diagnosis for promoting the control of infectious diseases.