Highly Sensitive Field Detection Technology for Anthrax Based on the CRISPR/Cas13a System

In this study, we established a highly sensitive on-site detection technology for Bacillus anthracis. Firstly, we integrated Multiple Enzyme Isothermal Rapid Amplification (MIRA) with the clustered regularly interspaced short palindromic repeats (CRISPR) /associated protein 13a (CRISPR/Cas13a) detection system to develop a highly sensitive CRISPR/Cas13a assay. After testing crRNA selection, MIRA primers, reaction temperature, and CRISPR detection conditions, the CRISPR/Cas13a detection system employing dual crRNAs achieved a detection limit of 1000 copies/mL for B. anthracis. Quantitative analysis was additionally attempted. Compared with other common respiratory pathogens, the assay demonstrated high specificity. In clinically simulated samples, all 20 positive specimens were correctly identified, and all 13 negatives were unambiguously classified as negative. Based on these findings, we established a CRISPR point-of-care testing technology. By developing a CRISPR point-of-care testing device together with a tested lyophilised reagent system, the device achieved a detection limit of 250 copies/mL and delivered results within 30 min. All positive samples were accurately identified, and every negative sample was classified as negative. Consequently, this study presents a highly sensitive and portable technology for on-site detection of B. anthracis. It holds significant value for on-site detection of emerging infectious diseases.