Multiplex detection of respiratory RNA viruses without amplification based on CRISPR-Cas13a immunochromatographic test strips

Acute respiratory infections, caused by RNA viruses like respiratory syncytial virus, influenza, rhinovirus, and coronavirus, are major global health threats. Real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) is the gold standard for detecting these viruses but is time-consuming, complex, and requires specialized equipment. There is a need for rapid, convenient, and multi-target detection methods to improve disease prevention and control. This study developed a multi-target immunochromatographic detection method using LbuCas13a protein and "band elimination" test strips for detecting SARS-CoV-2 and influenza virus. The method's performance was evaluated by testing known 5 positive and 4 negative samples for SARS-CoV-2 and comparing results with fluorescent PCR and colloidal gold methods. Detection sensitivity was quantified using digital PCR and qPCR. The immunochromatographic test strips showed 100% concordance with fluorescent PCR and colloidal gold methods in initial clinical SARS-CoV-2 detection. Subsequently, we used dual-target immunochromatographic test strips to detect 9 SARS-CoV-2 positive samples and 9 H3N2 positive samples. However, false negatives were observed in dual-target detection of SARS-CoV-2 and H3N2 samples, likely due to low sample concentration or sample degradation. The method had a minimum detection limit of 381.75 copies/µL, as determined by digital PCR and qPCR. The developed multi-target immunochromatographic detection method offers a rapid, low-cost, and simple approach for detecting both SARS-CoV-2 and influenza viruses. With high sensitivity, specificity, and reliability, this method holds promise as a practical tool for RNA virus diagnosis and improving public health response to respiratory infections.