Simultaneous Detection of Human Norovirus GI, GII and Hepatitis A Virus Using CRISPR-Cas12a-Based RT-RPA and Lateral Flow Strip Method.

Human norovirus (HuNoV) and hepatitis A virus (HAV) are highly prevalent and contagious foodborne pathogens that pose a significant threat to global public health. Current molecular detection methods such as RT-qPCR and RT-ddPCR are highly sensitive and specific but time-consuming, require specialized equipment, and are unsuitable for on-site detection. We developed a multiplex reverse transcription recombinase polymerase amplification (RT-RPA) assay coupled with CRISPR-Cas12a and lateral flow detection for rapid, simultaneous identification of HuNoV GI, GII, and HAV. Through rigorous in silico design and experimental validation, we optimized primer pools and crRNAs to ensure broad genotype coverage and high specificity. Using 2 µL of input per target per 50 µL reaction, the assay achieved limits of detection of 10¹ copies/µL (2 × 10¹ copies/reaction) for HAV, 10³ copies/µL (2 × 10³ copies/reaction) for GI HuNoV, and 10² copies/µL (2 × 10² copies/reaction) for GII HuNoV, with a total assay time of 50 min from purified RNA to final readout. No cross-reactivity occurred with other common foodborne viruses. Validation using total RNA extracted from shellfish digestive glands artificially spiked with RNA standards provided preliminary evidence supporting the feasibility of the method under laboratory conditions. This portable system shows strong potential as a rapid multiplex molecular detection platform.