A ERA/Cas12f1_ge4.1 biosensor for rapid, sensitive, and cost-effective detection of Chlamydia psittaci via fluorescence and lateral flow assays.

Rapid and accurate detection of Chlamydia psittaci, the causative agent of psittacosis, is crucial for both human and animal health but presents significant challenges, particularly in grassroots health institutions. Our previous PDTCTR fluorescence sensing platform, which combined the engineered Cas12f1_ge4.1 system with recombinase polymerase amplification (RPA), significantly enhanced detection efficiency. However, its requirement for specialized equipment, costly RPA reagents, and absence of visual output restricted its practical application in such environments. To address these limitations, we developed the ERA/Cas12f1_ge4.1 system, integrating Cas12f1_ge4.1 with the cost-effective Enzymatic Recombinase Amplification (ERA). This system enables sensitive detection of Chlamydia psittaci double-stranded DNA within 50 min through both fluorescence and colloidal gold lateral flow assay strips. The platform achieves detection limits of 10 copies/μL for fluorescence and 100 copies/μL for lateral flow. Clinical validation involving 93 parrot samples demonstrated high performance in both detection modes. Fluorescence detection achieved 95.4 % sensitivity, 100 % specificity, a 100 % positive predictive value (PPV), and a 90.3 % negative predictive value (NPV). Meanwhile, the lateral flow assay exhibited 92.3 % sensitivity, 100 % specificity, 100 % PPV, and an 84.8 % NPV. The ERA/Cas12f1_ge4.1 system offers a rapid, accurate, cost-effective, and visually interpretable diagnostic tool suitable for both laboratory and community health centers. This advancement holds significant potential for improving psittacosis diagnosis and control, particularly in resource-limited environments.