Clinical Utility of a New Automated Hepatitis C Virus Core Antigen Assay for Prediction of Treatment Response in Patients with Chronic Hepatitis C

Diagnostic performance of hepatitis C core antigen assay to identify active infections: A systematic review and meta-analysis

Hepatitis C virus (HCV) core antigen (HCVcAg) assay is an alternative for diagnosing HCV infection in a single step. This meta-analysis aimed to evaluate the Abbott ARCHITECT HCV Ag assay's diagnostic performance (validity and utility) for diagnosing active hepatitis C. PubMed, EMBASE, Scopus, Web of Science, and Cochrane Library were searched until 10 January 2023. The protocol was registered at the prospective international register of systematic reviews (PROSPERO: CRD42022337191). Abbott ARCHITECT HCV Ag assay was the test for evaluation, and nucleic acid amplification tests with a cut-off ≤50 IU/mL were the gold standard. Statistical analysis was performed using STATA with the MIDAS module and random-effects models. The bivariate analysis was conducted on 46 studies (18,116 samples). The pooled sensitivity was 0.96 (95% CI = 0.94-0.97), specificity 0.99 (95% CI = 0.99-1.00), positive likelihood ratio 141.81 (95% CI = 72.39-277.79), and negative likelihood ratio 0.04 (95% CI = 0.03-0.06). The area under the summary receiver operating characteristic curve was 1.00 (95% CI = 0.34-1.00). For active hepatitis C prevalence values of 0.1%-15%, the probability that a positive test was a true positive was 12%-96%, respectively, indicating that a confirmatory test should be necessary, particularly with a prevalence ≤5%. However, the probability that a negative test was a false negative was close to zero, indicating the absence of HCV infection. The validity (accuracy) of the Abbott ARCHITECT HCV Ag assay for screening active HCV infection in serum/plasma samples was excellent. Although the HCVcAg assay showed limited diagnostic utility in low prevalence settings (≤1%), it might help diagnose hepatitis C in high prevalence scenarios (≥5%).

Performance of HCV Antigen Testing for the Diagnosis and Monitoring of Antiviral Treatment: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

Active hepatitis C virus (HCV) infection is based on the detection of HCV RNA that it is effective but presents high cost and the need to hire trained personnel. This systematic review and meta-analysis is aimed at evaluating the diagnostic accuracy of HCV Ag testing to identify HCV cases and to monitor antiviral treatment including DAA treatment.

METHODS

The studies were identified through a search in PubMed, Lilacs, and Scopus from 1990 through March 31, 2020. Cohort, cross-sectional, and randomized controlled trials were included. Two independent reviewers extracted data and assessed quality using an adapted Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Our primary outcome was to determine the accuracy of HCV Ag detection for the diagnosis, which we estimated using random-effects meta-analysis.

RESULTS

Of 3,062 articles identified, 54 met our eligibility criteria. The studies described cohorts from 20 countries, including 14,286 individuals with chronic HCV individuals. Studies for ECLIA technology demonstrated highest quality compared to studies that used ELISA. The pooled sensitivity and specificity (95% CI) for HCV Ag detection of active HCV infection were 98.82% (95%CI = 98.04%; 99.30%) and 98.95% (95%CI = 97.84%; 99.49%), respectively. High concordance was found between HCV Ag testing and HCV RNA detection 89.7% and 95% to evaluate antiviral treatment.

CONCLUSIONS

According to our findings, HCV Ag testing could be useful to identify HCV active cases in low-resource areas. For antiviral treatment, HCV Ag testing will be useful at the end of treatment.

Hepatitis C virus antigen detection is an appropriate test for screening and early diagnosis of hepatitis C virus infection in at-risk populations and immunocompromised hosts

Early diagnosis remains key for effective prevention and treatment. Unfortunately, current screening with anti-hepatitis C virus antibody (anti-HCV Ab) test may have limited utility in the diagnosis of HCV infection and reinfection. This is of special concern to at-risk population, such as immunocompromised hosts and end-stage renal failure patients on hemodialysis. HCV antigen (Ag) could be useful in identifying the ongoing infection in such clinical scenarios. Hence, we aimed to study the utility of HCV Ag testing for the diagnosis of acute and chronic hepatitis C. Of 89 samples studied, 19 were from acute hepatitis C patients who were immunocompromised or were on hemodialysis, 43 were from active chronic hepatitis C patients and 27 were from patients treated for chronic hepatitis C. All samples were tested for HCV Ag using the Abbott ARCHITECT HCV Ag assay. HCV Ag was reactive in 19/19 samples from acute hepatitis C patients and 42/43 samples from active chronic hepatitis C patients. It was nonreactive in all samples from treated patients. The test showed a sensitivity and specificity of 98.4% and 100.0%, respectively. The positive and negative predictive values were 100.0% and 96.4%, respectively. The HCV antigen test has high clinical sensitivity and specificity and is useful for the diagnosis of acute and chronic hepatitis C infection in at-risk and immunocompromised patients. Its short turnaround time and relatively low cost are advantageous for use in patients on hemodialysis and other at-risk patients who require monitoring of HCV infection and reinfection.

HCV core antigen plays an important role in the fight against HCV as an alternative to HCV-RNA detection

Objective

To discuss the clinical significance of HCV‐cAg testing in the diagnosis, activity determination, and monitoring of therapeutic effectiveness of HCV infection and its advantages compared with HCV‐RNA and anti‐HCV antibodies detection.

Methods

By summarizing the published literature, the advantages and significance of HCV core antigen detection were sought.

Results

The expression of HCV‐cAg is highly consistent with that of HCV‐RNA, but compared with HCV‐RNA, detection of HCV‐cAg is easy to operate, time saving, and low cost. HCV‐cAg can be detected within 12~15 days after infection, and the window period can be shortened by5~7 weeks. HCV‐cAg is a serological indicator of virus replication, which can distinguish previous infection of HCV or current infection. HCV‐cAg detection is more suitable for immunocompromised, hemodialysis, organ transplant patients. HCV‐cAg also can be used to monitor antiviral efficacy and predict sustained virological response (SVR).

Conclusion

HCV core antigen has similar clinical sensitivity to NAT and can be used as a substitute for HCV‐RNA in the diagnosis of virus infection. Combined detection of HCV‐cAg and antibody serology can help doctors detect HCV infection earlier, accurately diagnose different stages of HCV infection, and evaluate the therapeutic effect of antiviral drugs, which are beneficial in the prevention and treatment of hepatitis C.

Hepatitis C core antigen: a simple predictive marker for treatment response to the new direct-acting antiviral drugs in chronic HCV Egyptian patients

Background

Successful eradication of hepatitis C virus (HCV) has great impact on the prognosis of HCV-related complications and the associated mortality. The development of the new direct-acting antiviral drugs (DAAs) has revolutionized the treatment of HCV infection. HCV core antigen (HCVcAg) is a recently developed marker that displayed a good correlation with HCV RNA assays. Our main objectives were to correlate between serum levels of HCVcAg and HCV RNA loads in chronic HCV patients as well as to explore the potential value of HCVcAg assay in predicting treatment response to the new DAAs. The study enrolled a total of 280 chronic HCV-infected patients scheduled to start the new regimen for treatment of chronic HCV by all-oral, interferon-free DAAs. According to the viral load, the studied individuals were arranged into three groups corresponding to mild, moderate, and sever viremia. Serum level of HCVcAg was determined by ELISA technique and HCV RNA viral loads were quantified using the real-time PCR system. The assays were performed three times for all participants: prior to initiation of treatment, at the end of treatment (week 12), and 3 months post-treatment cessation (week 24).

Results

A statistically significant difference between HCV RNA and HCVcAg baseline levels among different viremia groups was detected (P < 0.001). There was a significant positive correlation between HCV RNA and HCVcAg baseline values among all the studied cases (P < 0.05) with a correlation coefficient of 0.752, 0.976, and 1.00 respectively for mild, moderate, and severe viremia groups. 92.9% (260/280) of the studied patients achieved sustained virologic response, 3.6% (10/280) were non-responders, and 3.6% (10/280) had recurrent viremia/relapse as regards RT-PCR results.

Conclusion

HCVcAg is a promising alternative to HCV RNA assay. The ELISAs for HCVcAg proved excellent correlations with HCV RNA levels. Moreover, HCVcAg can be introduced as a simple and highly specific tool for monitoring the new DAA regimens particularly in low-resource settings.

Design of a novel rapid immunoassay for simultaneous detection of hepatitis C virus core antigen and antibodies

HCV is a potential cause of viral hepatitis, which leads to blood-borne chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Anti-HCV antibody detection assays detect HCV infection after approximately 70 days. HCV core antigen can be detected much earlier than anti-HCV antibodies. However, it disappears soon after the appearance of anti-HCV antibodies. Thus, there is a need for a rapid assay for simultaneous detection of HCV core antigen and anti-HCV antibodies for early diagnosis of HCV infection. A rapid diagnostic assay (HCV Ag-Ab Combo) for simultaneous detection of HCV core antigen and anti-HCV antibodies for early diagnosis of HCV infection was developed. HCV Ag-Ab Combo was evaluated in order to determine its potential for detection of HCV infection earlier than anti-HCV antibody detection assays. We compared the sensitivity of the newly developed assay with anti-HCV antibody detection assays (ELISA [HCV Ab ELISA] and rapid test [HCV Ab Rapid]) and HCV core antigen/anti-HCV antibody detection ELISA (HCV Ag-Ab ELISA). This study included 11 samples that were found positive in HCV RNA detection and HCV Ag-Ab ELISA but negative in HCV antibody detection assays (HCV Ab ELISA and rapid), 10 samples that were found positive in HCV Ag-Ab ELISA and HCV Ab ELISA but negative in HCV Ab Rapid, 69 samples that were found positive in HCV Ag-Ab ELISA, HCV Ab ELISA, and HCV Ab Rapid, and 509 samples that were found negative in HCV Ag-Ab ELISA, HCV Ab ELISA, and HCV Ab Rapid. Three seroconversion panels, PHV 913, PHV 911 (M) and PHV904-00-1.0, and a HCV RNA genotype qualification panel (2400-0182) acquired from Seracare Life Sciences (USA) were also tested. HCV Ag-Ab Combo showed a combined sensitivity and specificity of 100% when tested with 90 samples that were positive for HCV by HCV Ag-Ab ELISA and 509 HCV-negative samples. Its positive predictive value (PPV) and negative predictive value (NPV) were found to be 100%. It detected HCV infection approximately 7 to 12 days earlier than the HCV Ab detection assays, and its performance was not affected when testing different genotypes of HCV. HCV Ag-Ab Combo did not detect HCV infection as early as HCV RNA or HCV Ag-Ab ELISA. HCV Ag-Ab Combo provided a significant improvement for the early detection of HCV infection during the preseroconversion phase when compared with anti-HCV antibody detection assays. It could be a useful screening assay, and an alternative to HCV RNA detection or HCV Ag-Ab ELISA when nucleic acid technologies cannot be implemented.

Hepatitis C virus core antigen: A simplified treatment monitoring tool, including for post-treatment relapse

BACKGROUND

Simple, affordable diagnostic tools are essential to facilitate global hepatitis C virus (HCV) elimination efforts.

OBJECTIVES

This study evaluated the clinical performance of core antigen (HCVcAg) assay from plasma samples to monitor HCV treatment efficacy and HCV viral recurrence.

STUDY DESIGN

Plasma samples from a study of response-guided pegylated-interferon/ribavirin therapy for people who inject drugs with chronic HCV genotype 2/3 infection were assessed for HCV RNA (AmpliPrep/COBAS Taqman assay, Roche) and HCVcAg (ARCHITECT HCV Ag, Abbott Diagnostics) during and after therapy. The sensitivity and specificity of the HCVcAg assay was compared to the HCV RNA assay (gold standard).

RESULTS

A total of 335 samples from 92 enrolled participants were assessed (mean 4 time-points per participant). At baseline, end of treatment response (ETR) and sustained virological response (SVR) visits, the sensitivity of the HCVcAg assay with quantifiable HCV RNA threshold was 94% (95% CI: 88%, 98%), 56% (21%, 86%) and 100%, respectively. The specificity was between 98 to 100% for all time-points assessed. HCVcAg accurately detected all six participants with viral recurrence, demonstrating 100% sensitivity and specificity. One participant with detectable (non-quantifiable) HCV RNA and non-reactive HCVcAg at SVR12 subsequently cleared HCV RNA at SVR24.

CONCLUSIONS

HCVcAg demonstrated high sensitivity and specificity for detection of pre-treatment and post-treatment viraemia. This study indicates that confirmation of active HCV infection, including recurrent viraemia, by HCVcAg is possible. Reduced on-treatment sensitivity of HCVcAg may be a clinical advantage given the moves toward simplification of monitoring schedules.