Application of Real Time Loop Mediated Isothermal Amplification Assay on Dried Blood Spots in the Detection of HCV RNA among High Risk Patients

Detection of Hepatitis C virus (HCV) RNA, the earliest marker and a direct indicator of ongoing viral replication, is more reliable than the anti HCV antibodies for screening for an ongoing HCV infection especially in high-risk patients, such as those on hemodialysis (HD). Newer molecular methods that are affordable with a potential for point-of-care testing are being increasingly developed and recommended for an early and cost-effective detection of HCV RNA. An in house developed HCV Reverse Transcriptase Loop-mediated Isothermal Amplification (RT-LAMP) assay targeting the 5' un-translated region (UTR) of the HCV genome, was performed simultaneously on Plasma and Dried blood spots (DBS) from a study group of 300 high-risk patients {250 hemodialysis (HD) and 50 Chronic Liver Disease (CLD)} and 50 healthy age-matched individuals (control group). Among the study group, 145/300 (48.3%), (110/250 (44%) HD, and 35/50 (70%) CLDs) were positive for HCV RNA on the DBS. The HCV RT-LAMP was 100% sensitive and specific with a % CV less than 10, as compared to the gold standard HCV Real-Time PCR and a nested RT-PCR. The detection limit of all the assays was 50 copies of RNA /ml.