Sensitive and Robust One-Pot RPA-CRISPR/Cas12a Assay with Elimination of cis-Cleavage

The rapid detection technology utilizing CRISPR/Cas12a is characterized by high sensitivity, portability, and efficiency, making it a prominent focus in the field of point-of-care testing (POCT). However, it still has limitations in one-pot detection systems. This study developed a one-pot assay based on CRISPR/Cas12a and RPA (11bp+9ss one-pot assay), which nearly eliminates the cis-cleavage activity of Cas12a while retaining its trans-cleavage activity. Specifically, cis-cleavage was abolished by shortening the complementary length between the crRNA and the target to maintain the double-stranded conformation at the cis-cleavage site, whereas trans-cleavage activity was preserved by using an ssDNA complementary to the remaining region. The trans-cleavage activity was applicable to targets within a 200 bp range and under suboptimal PAM conditions. Moreover, rational design of the ssDNA enables effective discrimination of single-base mutations. The 11bp+9ss one-pot assay achieved a limit of detection (LOD) of 1 × 10⁰ copies/μL for various targets, demonstrating robust performance even in suboptimal RPA systems. Furthermore, the assay was successfully applied to the detection of Salmonella and Avian Leukosis Virus subgroup J (ALV-J) samples. Overall, the 11bp+9ss one-pot assay exhibits superior sensitivity and robustness, showing great potential for POCT of bacteria and viruses.