A Pre-Amplification-Free Modular Dual-CRISPR System for Enhanced Pathogen Detection Sensitivity

CRISPR/Cas12a is extensively utilized for pathogen detection owing to its high specificity and efficiency. However, traditional single-CRISPR/Cas12a encounters challenges due to its limited sensitivity, requiring pre-amplification of nucleic acids. This increases the complexity of the procedure and the potential for cross-contamination and false positives. Herein, a modular dual-CRISPR approach was developed coupled with hybridization chain reaction (HCR) for the universal and sensitive detection of pathogen nucleic acids without the need for pre-amplification. The system comprises two core modules: the first CRISPR/Cas12a recognition module specifically identifies pathogen targets and releases the activating agent, while the second CRISPR/Cas12a signal module is activated by this agent to initiate the HCR reaction for generating a strong fluorescent signal through DNA nanostructure self-assembly. Through rational design, we demonstrate the ability of this dual-CRISPR system to achieve attomolar (aM) level sensitivity for pathogen nucleic acid detection without pre-amplification, showing over six-order-of-magnitude higher sensitivity than a traditional single-CRISPR/Cas12a system. Additionally, the flexibility and versatility of the modular dual-CRISPR system have been confirmed for diverse pathogen targets, such as African swine fever virus (ASFV), severe fever with thrombocytopenia syndrome virus (SFTSV), and human papillomavirus type 16 (HPV-16) DNA. The system's practicality was demonstrated by examining ASFV quality control samples in complex environments. The exploration of the pre-amplification-free dual-CRISPR system offers a new perspective on enhancing pathogen nucleic acid detection systems.