A point-of-care screening test for hepatitis C virus (HCV) infection successfully identified all six major HCV genotypes with 98.6% sensitivity and 100% specificity. The test reliably detected HCV RNA faster than existing assays, according to scientists from the Institut Pasteur and Inserm, Paris, France, in collaboration with Genedrive, Manchester, UK. They report their findings in Gut.
“With our new test, which is rapid and easy to deploy, an infection can be confirmed at the point of need and a treatment decision made straight away if required,” senior author Darragh Duffy, PhD, Institut Pasteur, told MDLinx.
According to Dr. Duffy and coauthors, the point-of-care assay fulfills the recent Foundation for Innovative New Diagnostics/World Health Organization (WHO) target profile for HCV for decentralized testing in low- and middle-income countries—a key component of the WHO’s strategy to eliminate HCV as a public health threat by 2030.
The Genedrive HCV assay is a two-step procedure: a plasma or serum preparation step followed by a reverse transcription reaction to generate the complementary DNA (cDNA) from the target HCV RNA. The device can perform polymerase chain reaction (PCR) more quickly than a conventional platform, in approximately an hour. The instrument itself is a portable, battery-operated handheld device intended for use in the field.
Currently, HCV infection is often first identified by serologic testing followed by diagnostic confirmation of HCV RNA in circulation using PCR. Rapid serologic assays for HCV antibodies exist, but conventional PCR screening requires dedicated infrastructure and qualified staff, the investigators noted.
The researchers clinically validated the assay on 422 HCV-infected individuals and 503 negative controls from the Institut Pasteur and the National Health Service in Nottingham, UK. Results were obtained at first attempt in 97.2% of the samples. Low HCV RNA levels were identified as the sole independent factor significantly associated (P < 0.001) with the lack of a result at the first attempt in the HCV RNA positive case samples. Low HCV RNA level was the only factor significantly associated (P < 0.0001) with the false-negative results.
The study was then extended to a real-life clinical setting (Johannesburg, South Africa) that included 118 cases and 12 negative controls. Results were obtained at the first attempt for 124 of the 130 (95.4%) samples. Six samples were retested, and two of the six (33.3%) returned a result with the second test. All the samples that required retesting were positive for HCV RNA.
When compared with a reference test (Abbott RealTime HCV assay), the Genedrive HCV assay demonstrated 100% sensitivity and 100% specificity.
Linking diagnosis to treatment decisions is a major clinical challenge, the authors noted. They pointed out that in Europe, the percentage of cured individuals from initial viremic infections is only 4.1%, and treatment rates top out at 5% (in France and Germany). In resource-limited countries, the cure rate is less than 1%.
“These data show how both initial screening and linkage to care after diagnosis are still major challenges, one of the main consequences being the low number of individuals that are prescribed and adhere to treatment,” they wrote.
“Devices like Genedrive could have a major impact in improving the chronic HCV care continuum, as diagnosis through HCV RNA detection could be performed in a wide range of field settings and no intermediate visits would be required,” they concluded.
The study was funded by the European Commission FP7. Work performed in Nottingham and South Africa received additional financial support from Genedrive plc.