Establishment and evaluation of a naked-eye diagnostic assay for tuberculosis utilizing reverse isothermal amplification-assisted CRISPR-Cas in resource-limited settings.

INTRODUCTION

The current scenario of tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) has presented an almost insurmountable challenge to hospitals with high patient numbers. Delayed diagnosis of TB is a major hurdle in preventing the employment of efficient therapeutics, leading to the development of drug resistance. Hence, an easily accessible diagnostic method, particularly for resource for resource-limited settings, is pertinent for the rapid identification of MTB-infected patients. In pursuit of developing such an assay, the present study offers a CLAP-TB (CRISPR-Cas coupled RT-LAMP Amplification Protocol for Tuberculosis) assay, which will allow us to diagnose TB rapidly and visually.

METHODS AND

RESULTS

Herein, the visual MTB detection consists of a method utilizing 232 different samples (sputum, urine, serum) from 82 patients for reverse transcription loop-mediated isothermal amplification (RT-LAMP). Additionally, the assay also utilizes the integration of a CRISPR-Cas12-based system using different guide RNAs of IS6110 and an internal control POP7 (human RNase P) genes along with visual detection via lateral flow readout-based dipsticks with the unaided eye (~134 min). Overall, the limit of detection for CLAP-TB assay was up to 1 ag of RNA, while the clinical sensitivity and specificity were 98.27% and 100%, respectively, on the pilot scale.

CONCLUSION

Together, our CLAP-TB assay offers proof of concept for a rapid, sensitive, and specific method with the minimum technical expertise required for TB diagnosis in developing and resource-limited settings.