What is the role of quantitative hepatitis C virus (HCV) RNA assays in the diagnosis of hepatitis C (hep C) infection?

Updated: Oct 07, 2019
  • Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: BS Anand, MD  more...
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Quantitative assays ascertain HCV RNA quantity in blood, using signal amplification (branched DNA [bDNA] assay) or target amplification techniques (PCR, TMA). RT-PCR is more sensitive than bDNA testing. The HCV RNA level in blood helps predict the likelihood of a response to treatment, and the change in HCV RNA level can also be used to monitor the therapeutic response.

The same quantitative test should be used throughout therapy to avoid confusion, and results should be reported in international units (IU) to standardize data. The Versant HCV RNA Assay, version 3.0, is based on bDNA technology and has a dynamic range of 615-7,700,000 IU/mL. Another FDA-approved HCV quantitative test is the Aptima HCV Quant Dx Assay; its limit of detection is 3.9 IU/mL in plasma and 3.4 IU/mL in serum. [62]

The following are the best laboratory evidence of acute HCV infection:

  • A positive HCV RNA test in the setting of a negative HCV antibody test (seronegative “window” period)
  • A positive HCV antibody test after a prior negative HCV antibody test (seroconversion)

It should be noted that impaired antibody production in immunosuppressed individuals may result in misleading information.

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