A Rapid Assay for Hepatitis C Virus RNA Detection Using Reverse-Transcription Loop-Mediated Isothermal Amplification-Coupled CRISPR-Cas12b-Based Strategy.

BACKGROUND

Hepatitis C virus (HCV) diagnosis usually requires detection of antibody followed by HCV RNA. The requirement for 2 tests leads to major drop-offs in the cascade of care. Existing near-care HCV RNA tests have slow turnaround time and are expensive with limited availability. We aim to develop a cost-effective, rapid, and sensitive test for detection of HCV RNA to enhance screening, particularly in marginalized and remote populations.

METHODS

After RNA extraction from plasma, HCV RNA is reverse-transcribed and amplified using loop-mediated isothermal amplification with HCV-specific primers. The amplified HCV DNA is then detected via CRISPR-Cas12b with a fluorescence readout.

RESULTS

HCV RNA from patient samples with genotypes 1a, 1b, 2, 3a, and 4 was detected with high sensitivity and specificity. The lower limit of detection (LLOD) with HCV JFH1 plasmid (genotype 2) is 250 plasmid copies/mL (approximately 100 IU/mL). For clinical samples, we determined the LLOD for genotypes 1 and 3, the most common in North America. Using 500 μL of plasma, genotype 1 RNA ≥100 IU/mL was detected within 40-45 minutes, while genotype 3 had an LLOD of 5000 IU/mL. The clinical sensitivity was 100% in 72 HCV patient samples, including acute HCV and HCV/hepatitis B virus (HBV) coinfection. The specificity was 100%, with no false-positives in 33 HCV-negative samples, including those with HBV or human immunodeficiency virus/HBV coinfection.

CONCLUSIONS

Our assay shows high specificity and sensitivity to detect HCV RNA directly from plasma within 45 minutes and hence could be used for efficient screening and diagnosis of HCV infection globally.