Hepatitis C virus (HCV) assays are used to evaluate for HCV infection.
HCV antibody assays include the following:
Abbott Laboratories - Abbott HCV EIA 2.0
OraSure Technologies - OraQuick HCV Rapid Antibody Test
Ortho-Clinical Diagnostics - ORTHO HCV Version 3.0 ELISA, VITROS Anti-HCV assay
Roche Diagnostics - Elecsys Anti-HCV assay
HCV RNA qualitative assays include the following:
Chiron - PROCLEIX HIV-1/HCV Assay
Roche Molecular Diagnostics - COBAS Amplicor HCV Test (v2.0), COBAS Ampliprep/COBAS Amplicor HCV Test (v2.0), COBAS Ampliscreen HCV Test (v2.0)
Siemens Healthcare Diagnostics - Versant HCV RNA Qualitative Assay
HCV RNA quantitative assays include the following:
Abbott Molecular - RealTime HCV
Roche Molecular Diagnostics - COBAS Ampliprep/COBAS TaqMan HCV Test, COBAS TaqMan HCV Test (v2.0) for use with the High Pure System
Siemens Healthcare Diagnostics - Versant HCV RNA 3.0 Assay (bDNA)
HCV genotyping assays include the following:
Roche Molecular Diagnostics - LINEAR ARRAY Hepatitis C Virus Genotyping Test (Europe only; not approved by the US Food and Drug Administration [FDA])
Siemens Healthcare Diagnostics - Trugene HCV Genotyping Assay (research use only), Versant HCV Genotype 2.0 Line Probe Assay (research use only)
Currently, 2 hepatitis C virus (HCV) enzyme immunoassays (EIAs) are approved by the US Food and Drug Administration (FDA) for clinical use: Abbott HCV EIA 2.0 and ORTHO HCV Version 3.0. These assays are 99% specific but cannot distinguish acute from chronic infection. The most recent third-generation EIA detects antibodies against core protein and nonstructural proteins 3, 4, and 5 and can yield positive results an average of 8 weeks after the onset of infection.
Two other serologic assays are FDA-approved: VITROS Anti-HCV , an enhanced chemiluminescence immunoassay (CIA), and Elecsys Anti-HCV, an electrochemiluminescence (ECL) assay.
The OraQuick HCV Rapid Antibody Test is designed for use with venipuncture whole-blood samples. The test has an estimated sensitivity of at least 99%. The device uses a test strip coated with HCV antigens. After the blood sample is mixed with buffer, the test strip is placed into the test vial. The strip is read 20-40 minutes later; the appearance of a colored line indicates the detection of anti-HCV. All positive test results should be confirmed with further testing.
Assays for serum HCV RNA use signal amplification (branched DNA [bDNA]) or target amplification techniques (real-time polymerase chain reaction [RT-PCR], transcription-mediated amplification [TMA]) (see Tables 1 and 2 below).[1, 2, 3]
Table 1. FDA-Approved Qualitative HCV RNA Assays (Open Table in a new window)
||Lower Limit of Detection (IU/mL)
|COBAS Amplicor HCV Test (v2.0)
|COBAS Ampliprep/COBAS Amplicor HCV Test (v2.0)
|COBAS Ampliscreen HCV Test (v2.0)
|Versant HCV RNA Qualitative Assay
|PROCLEIX HIV-1/HCV Assay
FDA = US Food and Drug Administration; HCV = hepatitis C virus; RT-PCR = real-time polymerase chain reaction; TMA = transcription-mediated amplification.
Table 2. FDA-Approved Quantitative HCV RNA Assays (Open Table in a new window)
||Dynamic Range (IU/mL)
|Versant HCV RNA 3.0 Assay (bDNA)
||Signal amplification (bDNA)
||615 to 7.7 ◊ 106
|COBAS Ampliprep/COBAS TaqMan HCV Test
||Fully automated RT-PCR
||43 to 6.9 ◊ 107
|COBAS TaqMan HCV Test v2.0 for use with High Pure System
||25 to 3 ◊ 108
|Abbott RealTime HCV
||12 to 1 ◊ 108
bDNA = branched DNA; FDA = US Food and Drug Administration; HCV = hepatitis C virus; RT-PCR = real-time polymerase chain reaction.
HCV genotyping can be performed by means of direct sequence analysis, reverse hybridization to genotype-specific oligonucleotide probes, or restriction fragment length polymorphisms (RFLPs).
The Trugene HCV genotyping assay is based on direct sequencing followed by comparison with a reference sequence database. The Versant HCV line probe assay (formerly known as INNO LiPA HCV II) is based on reverse hybridization of a PCR amplicon on a nitrocellulose strip coated with genotype-specific oligonucleotide probes; the Roche Linear Array test uses a similar methodology.
The diagnosis of acute or chronic HCV infection requires testing with serologic assays for specific antibody to HCV (anti-HCV) and molecular assays for HCV RNA. Anti-HCV testing is also used to screen for infection. In the past, qualitative HCV RNA assays were preferred to quantitative assays for diagnosis because of their greater sensitivity. However, the sensitivities of the newer quantitative HCV RNA assays are comparable to those of qualitative assays, and quantitative testing is now recommended for diagnosis.
In addition to conventional serologic testing, a portable and easy-to-use assay, the OraQuick HCV Rapid Antibody Test, was approved by the US Food and Drug Administration (FDA) in June 2010. The new test provides results in 20 minutes and is indicated for HCV screening in persons who are at risk for hepatitis or show signs or symptoms of hepatitis. The test should not be used to make a final diagnosis of HCV infection.
HCV genotyping is helpful for predicting the likelihood of response and planning the duration of treatment. However, none of the commercially available tests have been approved by the FDA.
The AASLD guidelines make the following recommendations for diagnostic testing of acute and chronic HCV infection :
Patients suspected of having acute or chronic HCV infection should first be tested for anti-HCV
HCV RNA testing should be performed in patients with a positive anti-HCV test result; patients for whom antiviral treatment is being considered, using a sensitive quantitative assay; and patients with unexplained liver disease whose anti-HCV test yields negative results and who are immunocompromised or are suspected of having acute HCV infection
HCV genotyping should be performed in all HCV-infected persons before interferon-based treatment to assist in planning the dosage and duration of therapy and to estimate the likelihood of response
Differentiation of acute from chronic hepatitis C virus (HCV) infection depends on the clinical presentation (eg, the presence of symptoms or jaundice or elevation of serum alanine aminotransferase [ALT] levels). HCV RNA can be detected in serum as early as 2 weeks after an acute exposure, whereas anti-HCV generally is not detectable before 8-12 weeks. The interpretation of HCV assays is outlined in Table 3.
Table 3. Interpretation of HCV Assays (Open Table in a new window)
||Acute or chronic HCV, depending on clinical context
||Resolution of HCV; acute HCV during period of low-level viremia
||Early acute HCV infection; chronic HCV in setting of immunosuppressed state; false-positive HCV RNA test result
||Absence of HCV infection
False-negative results for anti-HCV serology can occur in immunocompromised persons, such as those with HIV type 1 infection, renal failure, or HCV-associated essential mixed cryoglobulinemia. False-positive enzyme immunoassay (EIA) results are more likely to occur in persons without risk factors and in those without signs of liver disease, such as blood donors or healthcare workers.
Serum HCV RNA levels help predict the likelihood of a response to treatment, and quantitative changes in serum HCV RNA can also be used to monitor treatment response. To avoid confusion, the same quantitative test should be used throughout therapy, and results should be reported in international units (IU) so that the data are readily comparable.
Genotyping is useful in the clinical management of HCV infection for predicting the likelihood of response and determining the optimal duration of therapy. Patients with genotypes 1 and 4 are generally treated for 12 months, whereas 6 months of treatment is sufficient for other genotypes.
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