CRISPR/Cas12a-RCA enables ultrasensitive detection of circulating free DNA for noninvasive diagnosis of echinococcosis

OBJECTIVE: To develop a novel non-invasive CRISPR/Cas12a-RCA assay for the primary screening of human echinococcosis via detection of circulating Echinococcus cell-free DNA (cfDNA) in peripheral blood. METHODS: Plasma cfDNA from 20 AE patients was analyzed via high-throughput sequencing to identify conserved repetitive Echinococcus fragments.A one-pot RCA system coupled with CRISPR/Cas12a was optimized for Echinococcus-cfDNA detection. The limit of detection (LOD) was determined using serially diluted synthetic standards, while specificity was validated through mismatch probes and cross-reactivity testing. Clinical validation included 50 AE cases, 22 cystic echinococcosis (CE) cases, 43 non-Echinococcus hepatic disease (HD) cases, and 53 healthy controls (CON). RESULTS: A conserved repetitive 28S rDNA fragment (pan-Echinococcus-28S) was identified as a biomarker. The CRISPR/Cas12a-RCA assay achieved amplification within 30 minutes at 37 °C, with a linear range of 1 aM to 100 pM and an LOD of 1.41 aM. Visual detection limits were 10 aM (UV light) and 1 aM (blue light). The assay demonstrated high sensitivity (87.5%) and specificity (96.9%, AUC = 0.933) in distinguishing Echinococcus infection (AE/CE) from HD and CON. CONCLUSION: The optimized one-pot CRISPR/Cas12a-RCA system enables rapid and ultrasensitive detection of pan-Echinococcus cfDNA, providing a cost-effective and highly accurate solution for the primary screening of echinococcosis.