New Automated Hepatitis C Virus (HCV) Core Antigen Assay as an Alternative to Real-Time PCR for HCV RNA Quantification

Abstract

An automated hepatitis C virus (HCV) antigen (Ag) assay was evaluated with clinical samples. Determination of HCV Ag and RNA levels in 282 subjects using Abbott HCV Ag and Roche Cobas TaqMan assays revealed that these two tests were highly correlated (r ‫؍‬ 0.9464). Thus, the HCV Ag assay could be an alternative test to quantitative reverse transcription-PCR.Hepatitis C virus (HCV) infection usually causes a progressive disease that can result in chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (12). Diagnosis and monitoring of HCV infection are commonly based on anti-HCV assays, recombinant immunoblotting, and HCV RNA viral load in current clinical practices (13). However, anti-HCV assays have limitations, including a lack of detection sensitivity in the early window periods of 45 to 68 days after infection (5), although second-and third-generation anti-HCV assays have improved. Real-time quantitative reverse transcription-PCR (qRT-PCR) analyses for measuring viral loads also have some drawbacks. These techniques are not completely free from contamination and false-positive results. Furthermore, some PCR assays require technical skills and may also be labor intensive and expensive.HCV core antigen (Ag) tests have been introduced to supplement anti-HCV tests or HCV qRT-PCR analyses over the last decade (1, 16), and these quantitative HCV Ag assays could be used for the monitoring of antiviral therapy as well as for diagnosis of HCV infection (3, 6). Furthermore, the HCV Ag assay could also be useful in monitoring immunocompromised patients and those undergoing hemodialysis (10). However, most of the past studies detecting HCV Ag utilized enzyme-linked immunosorbent assays (ELISAs) or enzyme immunoassays (EIAs) (4,7,14,18), which may need considerable time and skills. Recently, a fully automated chemiluminescent immunoassay (CLIA) with higher sensitivity and throughput was developed to overcome shortcomings of the conventional core Ag assays (11). Thus, we evaluated the newly introduced HCV Ag assay and compared it with a quantitative RNA assay to verify the utility of this automated Ag assay as an alternative to HCV RNA qRT-PCR.A total of 282 serum samples from the 268 patients who visited a university hospital in Korea with suspected HCV infection were collected from January to April 2009. HCV Ag and qRT-PCR assays were performed for all 282 samples, while anti-HCV antibodies and liver enzymes were measured in 279 and 250 subjects, respectively. HCV genotyping was also performed in 127 specimens. Serum HCV Ag was determined by an Abbott Architect i2000SR analyzer (Abbott Laboratories, Abbott Park, IL) with an HCV Ag assay kit (Abbott Japan Co., Ltd., Tokyo, Japan). The Architect HCV Ag assay is a two-step chemiluminescent microparticle immunoassay for the quantitation of HCV core Ag. The sample volume required is about 110 l, and the total assay time is 36 min. The cutoff value is 3.0 fmol/liter; thus, HCV Ag levels below 3.0 fmol/liter were considered nonreactive. HCV RNA viral load was determi...

Comparison of HCV core antigen and anti-HCV with HCV RNA results

“…Our specificity and positive predictive values were found as 100% and similar results were obtained in comparison with the other studies showing that there were no false-positive results 4,6,13 . However, our sensitivity (86,5%) and negative predictive value (59.4%) were a little bit lower than those of the other studies 4,6,13 . This was due to our higher rate of false negative results.…”

“…Nucleic acid testing (NAT) for the detection of HCV RNA remains the gold standard for diagnosing active HCV infections. However, in comparison with HCV core Ag and anti-HCV antibody tests, the need for experienced staff, special laboratory conditions and equipment and the need for standardisation are drawbacks of HCV RNA assays 1,6 . Furthermore, depending on exposure to the virus, detection of HCV RNA shows differences in patients with no antibody found 2 .…”

“…The results of recent studies indicated that measurements of HCV core Ag in serum or plasma can be used as indirect markers of HCV replication 7, 8, 9, 10. The majority of the previously used enzyme-linked immunosorbent assays (ELISAs) or EIAs detecting HCV core Ag may have required time and skill to conduct. However, a fully automated CLIA with higher sensitivity has been developed to overcome the shortcomings of the conventional core Ag assays 6 . In this study, we aimed to determine the significance of testing of HCV core Ag in laboratory diagnosis of HCV infection, to compare HCV core Ag, anti-HCV antibody and HCV RNA levels, and to investigate the correlation between serum HCV core Ag levels and HCV RNA levels for the diagnosis of HCV infection.…”

“…In the last decade, several HCV core Ag assays have been developed, due to the problems associated with HCV RNA assays 4,6 . The results of recent studies indicated that measurements of HCV core Ag in serum or plasma can be used as indirect markers of HCV replication 7, 8, 9, 10. The majority of the previously used enzyme-linked immunosorbent assays (ELISAs) or EIAs detecting HCV core Ag may have required time and skill to conduct.…”

Evaluation Of An Enzyme Immunoassay For Hepatitis C Virus Core Antigen As A Diagnostic Test For Detection Of Hepatitis C Virus Infection In Comparison To Real-Time RT-PCR

“…This protein is the ideal target for detecting the HCV antigen. This test has the advantages of easy testing and rapid reporting (Park et al, 2010).…”