An RPA-CRISPR/Cas12a-based rapid and sensitive nucleic acid method for detection of Toxoplasma gondii in tissue and blood samples.

Toxoplasma gondii is a zoonotic pathogen that can infect humans and a wide range of warm-blooded animals, posing a significant threat to human health and the livestock industry. The development of a time-saving, highly sensitive, and specific method for the detection of T. gondii in tissue and blood samples is crucial to the monitoring, prevention, and control of toxoplasmosis. In this study, we evaluated the efficiency of a previously described method, termed REPORT, that integrates recombinase polymerase amplification with CRISPR/Cas12a for the detection of T. gondii nucleic acids. We evaluated the limit of detection (LOD) and specificity of the extended REPORT method using prepared target DNA in addition to tissue and blood samples. Furthermore, we validated the accuracy of T. gondii detection in clinical samples using the REPORT-based method in comparison with nested PCR based on the B1 gene. Sensitivity tests showed that the LOD of the REPORT-based fluorescence method and the lateral flow strip method were 3.7 copies /μL for target DNA, 3.1 tachyzoites/g for tissue samples, and five tachyzoites/mL for blood samples. Specificity tests suggested that the REPORT method had good specificity and did not cross-react with several common parasites. The method performed well for clinical DNA samples, demonstrating its ability for use in on-site detection.IMPORTANCEToxoplasma gondii can infect over 200 species of warm-blooded animals, including humans, posing not only a significant threat to public health systems but also causing substantial economic losses to the global livestock industry. Current diagnostic methods are slow, equipment-dependent, and impractical for field use. This study addresses these limitations by developing REPORT, a rapid, ultrasensitive nucleic acid test combining recombinase polymerase amplification and CRISPR/Cas12a. The REPORT detects T. gondii in tissue and blood samples within 1 h at low cost, requiring only a portable heater. Its visual results (fluorescence or test strips) enable on-site use without specialized training, achieving 100% accuracy versus nested PCR. With a sensitivity of 3.1 parasites per gram of tissue and five parasites per milliliter of blood, this method revolutionizes toxoplasmosis screening in resource-limited clinics, farms, and food safety inspections, empowering timely interventions to curb transmission and improve public health outcomes.