Immunoassay for the qualitative dual detection of hepatitis C virus (HCV) core antigen and antibodies to HCV
Hepatitis C is an inflammatory liver disease caused by infection with the hepatitis C virus (HCV), which can cause both acute and chronic hepatitis.1 HCV is a member of the Flaviviridae family and has a single-stranded, positive-sense RNA genome, which encodes 3 structural and 7 non-structural proteins.2,3 HCV is classified into 8 genotypes with a total of currently 93 subtypes.4
Hepatitis C represents a major global health burden: the total global prevalence of antibodies against HCV, indicating past exposure to HCV, was estimated to be 1.6 %, corresponding to approx. 115 million people with a past infection.5 Globally, an estimated 50 million people have an active HCV infection indicated by HCV RNA positivity, with about 1.0 million new infections occurring per year. A significant number of chronically infected will develop liver cirrhosis or hepatocellular carcinoma (HCC). About 242,000 people died from hepatitis C-related liver diseases in 2022.1,6
Most acute HCV infections (70 – 85 %) are asymptomatic and approximately 15 – 45 % of patients will clear acute infection. In case of symptomatic acute hepatitis C, symptoms usually appear within 7 – 8 weeks after exposure and consist of jaundice, malaise, and nausea (similar to hepatitis A and B).2,7-9 Chronic HCV infection is characterized by persistence of HCV RNA in the blood for longer than 6 months. Most chronic infections will lead to hepatitis and to some degree of fibrosis, which may be accompanied by relatively nonspecific symptoms such as fatigue. 20 % of people with chronic hepatitis C will eventually develop cirrhosis.2,7-9 Once cirrhosis is established, the risk of developing hepatocellular carcinoma (HCC) is 1 – 4 % per year.10 Highly efficacious direct-acting antiviral (DAA) combination therapies are now available which can cure more than 95 % of treated patients.11
Infection with HCV and the state of infection (acute or chronic) can be diagnosed by measuring HCV‑specific antibodies (anti‑HCV), and HCV RNA or viral antigens in patient serum or plasma samples. Measurement of the alanine aminotransferase (ALT) level is an associated indicator of liver inflammation or damage due to infection.2,7,12 International guidelines recommend initial screening by anti‑HCV testing. A positive anti-HCV result is recommended to be followed up by measuring HCV RNA or HCV antigen (HCV Ag) as markers of active infection.8,13-15
Anti-HCV antibodies are detected on average 6 – 12 weeks after infection, while HCV RNA and core antigen appear much earlier already in the incubation and acute phases of infection (2-14 days and 10-30 days after infection, respectively). Detection of HCV core antigen, as a surrogate marker of HCV RNA, is thus a means to shorten the diagnostic window period and confirm active infection.2,9,13,15-18
The Elecsys® HCV Duo assay comprises two test modules, one for the detection of HCV Ag (HCVAG) and one for the detection of anti-HCV (AHCV). HCVAG uses monoclonal antibodies for the detection of the HCV core antigen. AHCV uses synthetic peptides and a recombinant protein representing the core, NS3 and NS4 antigens for the detection of anti‑HCV antibodies. With the Elecsys® HCV Duo assay, HCV core antigen as well as antibodies to HCV can be detected simultaneously from a single specimen in two separate, but parallel reactions. The Elecsys® HCV Duo main test result is automatically calculated by the analyzer, while the individual HCV Ag and anti‑HCV results are also accessible.19
* coefficient of variation; ** confidence interval
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