Clinical usefulness of total hepatitis C virus core antigen quantification to monitor the response to treatment with peginterferon alpha-2a plus ribavirin*

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.

Quantitative measurement of HCV core antigen for management of interferon-free therapy in HCV-infected patients

BACKGROUND

According to current recommendations diagnosis and management of HCV infection need detection and quantification of nucleic acids. In the era of direct-acting antivirals (DAA) it is essential to develop an inexpensive and simple method replacing polymerase chain reaction. Since there is no available data on HCV core antigen (HCVcAg) versus HCV RNA kinetics in the early phase of treatment with DAA, we carried out this study to evaluate the possible application of HCVcAg quantitative measurement for management of HCV infection.

METHODS

33 patients with HCV infection were enrolled and treated with either ombitasvir/paritaprevir/ritonavir ± dasabuvir ± ribavirin (OBV/PRV/r±DSV±RBV) or ledipasvir/sofosbuvir (LDV/SOF). Samples for quantitative HCV RNA and HCVcAg measurement were collected at the baseline, after 1, 7, 28 days and at the end of treatment, and then after 12 and 24 weeks of post-treatment follow-up.

RESULTS

There was positive correlation between HCVcAg and HCV RNA levels at the baseline and after 1 day of treatment. Mean HCVcAg concentration declined faster than HCV RNA levels during the treatment phase. At week 4 HCV RNA was undetectable in 24, whereas HCVcAg in 28 patients. At the end of treatment and after 12 weeks of follow-up all patients were undetectable for both HCV RNA and HCVcAg.

CONCLUSIONS

HCVcAg concentration and its early on-treatment testing can predict virological response. Simple testing procedures and significantly lower cost compared to HCV RNA testing support possible replacement of the viral load measurement in management of the majority of HCV-infected patients.

Clinical value of hepatitis C virus core antigen levels in monitoring acute hepatitis C spontaneous clearance or treatment-induced clearance

BACKGROUND AND AIM

To observe the clinical value of hepatitis C virus (HCV) core antigen (HCcAg) levels in monitoring acute HCV infection in patients with spontaneous clearance (SC) or clearance induced by antiviral therapy.

METHODS

Patients with iatrogenic HCV infection (n = 104) were enrolled at the Shengjing Hospital, China Medical University, between 5 February 2013 and 3 April 2013. All cases were diagnosed with acute HCV infection, enrolled within 90 days of infection, and followed for 12 to 16 weeks. Blood was collected every month. HCV RNA and HCcAg levels were detected. From week 16, patients without SC were treated with pegylated-interferon and the HCV RNA and HCcAg levels were observed monthly. Follow-up was 7.5 (5.0 to 10.4) months. The Spearman correlation analysis was performed to determine the correlation between HCV RNA and HCcAg. Logistic regression analysis was used to determine the association of baseline HCV RNA and HCcAg levels with SC.

RESULTS

Ten patients (9.62%) showed SC, with a negative conversion time of 57 (14 to 143) days. During follow-up, HCV RNA and HCcAg expression levels were positively correlated for each patient (except on the sixth month), but the levels of HCV RNA and HCcAg were not associated with HCV infection SC.

CONCLUSIONS

HCcAg levels could be of value for monitoring the course early HCV infection, but could not predict SC of HCV infection.

Sensitivity of hepatitis C virus core antigen and antibody combination assays in a global panel of window period samples

BACKGROUND

Hepatitis C virus (HCV) antigen and antibody combination assays have been launched as a cost-effective alternative to nucleic acid testing (NAT) for reducing the antibody-negative window period (WP). Later, a HCV antigen chemiluminescence immunoassay (CLIA) became available.

STUDY DESIGN AND METHODS

A panel composed of 337 HCV NAT-yield samples that were characterized for viral load (VL) and genotype was used to compare the sensitivity of two combination enzyme-linked immunosorbent assays (Monolisa, Bio-Rad; and Murex, formerly Abbott) and a HCV antigen CLIA (Abbott). Analytic sensitivity was compared with HCV RNA detection using Ultrio (Grifols) by testing serial dilutions of 10 genotype (gt)1 to gt4 samples.

RESULTS

HCV antigen CLIA detected 92.4% of samples, whereas Monolisa and Murex detected 38.3 and 47.5%, respectively. In the HCV RNA VL range of 10(5) to 10(7) IU/mL, Monolisa and Murex detected 38% to 56% of gt1, 85% to 78% of gt2, and 21% to 37% of gt3. The overall geometric mean 50% limit of detection (range) of Ultrio on gt1 to gt4 dilution series was 3.5 (1.2-7.7) copies/mL, compared to 3.3 × 10(6) (4.4 × 10(5) -2.7 × 10(7) ), 3.4 × 10(6) (2.2 × 10(5) -4.2 × 10(7) ), and 2728 (415-7243) copies/mL for Monolisa, Murex, and HCV antigen CLIA, respectively.

CONCLUSION

Analytical sensitivity of NAT was on average 1 million- and 780-fold higher than combination assays and HCV antigen CLIA, respectively. Relative sensitivities of combination assays differed for genotypes with Murex being more sensitive for gt1 and gt3 and Monolisa more sensitive for gt2. Although being less sensitive than NAT, combination assays could be considered in resource-limited settings since they detect 38% to 47% of seronegative WP donations.

Tools for the diagnosis of hepatitis C virus infection and hepatic fibrosis staging

Hepatitis C virus (HCV) infection represents a major public health issue. Hepatitis C can be cured by therapy, but many infected individuals are unaware of their status. Effective HCV screening, fast diagnosis and characterization, and hepatic fibrosis staging are highly relevant for controlling transmission, treating infected patients and, consequently, avoiding end-stage liver disease. Exposure to HCV can be determined with high sensitivity and specificity with currently available third generation serology assays. Additionally, the use of point-of-care tests can increase HCV screening opportunities. However, active HCV infection must be confirmed by direct diagnosis methods. Additionally, HCV genotyping is required prior to starting any treatment. Increasingly, high-volume clinical laboratories use different types of automated platforms, which have simplified sample processing, reduced hands-on-time, minimized contamination risks and human error and ensured full traceability of results. Significant advances have also been made in the field of fibrosis stage assessment with the development of non-invasive methods, such as imaging techniques and serum-based tests. However, no single test is currently available that is able to completely replace liver biopsy. This review focuses on approved commercial tools used to diagnose HCV infection and the recommended hepatic fibrosis staging tests.

Low-dose pegylated interferon-α2a plus ribavirin therapy for elderly and/or cirrhotic patients with HCV genotype-1b and high viral load

BACKGROUND

Pegylated interferon (PEG-IFN) plus ribavirin therapy is still recommended for elderly and/or cirrhotic patients. This study examined whether sustained virological response (SVR) to low-dose PEG-IFN-α2a plus ribavirin therapy for elderly and/or cirrhotic patients could be predicted based on viral reduction within 2 weeks after therapy initiation or interleukin IL-(28B) polymorphism and viral mutations.

METHODS

Participants comprised 115 elderly (≥65 years) and/or cirrhotic patients with genotype-1b and high viral load. Reduced doses of PEG-IFN-α2a (90 μg/kg/week) and ribavirin (400-800 mg/day) were administered for 48-72 weeks based on virological response of each patient.

RESULTS

SVR was achieved in 34% (39/115), and treatment was discontinued in 15% (17/115). Univariate analysis identified age, α-fetoprotein, fibrosis marker, interferon sensitivity-determining region (ISDR), IL-28B polymorphism and level of viral reduction within 2 weeks as factors contributing significantly to SVR. However, no significant differences were noted in core amino acid substitutions. Multivariate analysis identified age, hyaluronic acid, ISDR and viral reduction as factors independently associated with SVR. Positive predictive value (PPV) and negative predictive value (NPV) of SVR based on the level of viral reduction at 2 weeks (cutoff level, 1.7 log IU/ml) were 83% and 84%, respectively. The PPV of SVR based on IL-28B major and ISDR mutant was 70%, and the NPV of SVR based on IL-28B minor and wild-type ISDR was 89%.

CONCLUSIONS

Evaluations of viral reduction at 2 weeks or both IL-28B and ISDR are useful to predict SVR to low-dose PEG-IFN-α2a plus ribavirin therapy for elderly and/or cirrhotic patients.

Prediction of sustained response to low-dose pegylated interferon alpha-2b plus ribavirin in patients with genotype 1b and high hepatitis C virus level using viral reduction within 2 weeks after therapy initiation

AIM

  Continuation of pegylated interferon (PEG-IFN) plus ribavirin at the recommended dose is difficult in elderly patients and/or patients with cytopenia or complications. Whether the therapeutic efficacy of low-dose PEG-IFN plus ribavirin therapy could be predicted based on virological response within 2 weeks of therapy initiation was evaluated.

METHODS

  A total of 106 patients with a high viral load of genotype-1b hepatitis C virus (HCV) underwent low-dose PEG-IFN plus ribavirin therapy. PEG-IFN alpha 2b (0.75 µg/kg per week) and ribavirin (600-800 mg/day) were administered for 48 weeks.

RESULTS

  Sustained virological response (SVR) was achieved in 37%, and treatment was discontinued in 9%. On univariate analysis of SVR-contributing factors, significant differences were noted in the white blood cell count, platelet count, fibrosis markers, and viral reduction within 2 weeks from therapy initiation. On multivariate analysis, the platelet count and the reduction in the HCV core antigen level at week 2 were independent factors. The positive predictive value (PPV) and the negative predictive value (NPV) for SVR based on a 1-log or greater HCV-RNA level reduction at week 2 were 65% and 90%, respectively, and those based on HCV core antigen level at week 2 were 64% and 97%, respectively. PPV and NPV based on a 2-log or greater reduction of the RNA level were 86% and 67%, respectively, and those based on the core antigen level were 93% and 69%, respectively.

CONCLUSION

  Evaluation of viral reduction at week 2 after therapy initiation is useful for predicting SVR to low-dose PEG-IFN plus ribavirin therapy.

[Evaluation of ARCHITECT HCV core antigen assay]

BACKGROUND

Hepatitis C virus (HCV) core antigen (Ag) levels are known to be well correlating with HCV RNA levels, and may be used as an alternative marker of HCV replication for monitoring the response to HCV treatment. However, the low sensitivity of HCV core Ag assay has been an obstacle for clinical use. In this study, recently developed ARCHITECT HCV Ag assay (Abbott Laboratories, USA) was evaluated for analytical performance and clinical usefulness.

METHODS

A total of 109 sera from HCV infected patients including various genotypes of HCV (1b, 2, 2a/2c, 2b, and 3a) and 20 sera from healthy donors were used for evaluating the sensitivity, precision, and linearity of the HCV core Ag assay. The cross reactivity with HIV, hepatitis B virus and myeloma proteins (N=5, each) and correlation with HCV RNA PCR assay were also evaluated.

RESULTS

The sensitivity of the HCV core Ag assay was 97.2% (106/109) and there were no false positive results and cross reactivity. The within-run, between-run and between-day CVs were 3.0%, 2.5% and 3.0%, respectively. The levels of HCV core antigen showed a good correlation with those of HCV RNA quantification (r=0.940). The HCV Ag assay showed an excellent linearity in the range from 0.63 to 17,114 fmol/L (r=0.999).

CONCLUSIONS

The ARCHITECT HCV Ag assay was good in sensitivity, precision, and linearity and its results well correlated with HCV RNA levels. This assay could be used as a good marker of viral replication for monitoring the therapy response in chronically HCV infected patients.

Analytical performance characteristics and clinical utility of a novel assay for total hepatitis C virus core antigen quantification

The detection and quantification of hepatitis C virus (HCV) core antigen in serum or plasma by the use of different assay formats have previously been shown to represent useful markers of viral replication. In the present study, the intrinsic performance characteristics and the potential clinical utility of a novel assay for the quantification of total HCV core antigen were comprehensively assessed by using clinical serum samples and specimens contained in various evaluation panels. The Architect HCV Ag assay showed a specificity of 100%. The intra- and interassay coefficients of variation ranged from 3.6 to 8.0% and from 4.7 to 9.5%, respectively. Except for HCV genotype 2 isolates, the analytical sensitivity was always less than 10 fmol core antigen/liter, corresponding to approximately 500 to 3,000 IU of HCV RNA/ml. Linearity was guaranteed throughout the dynamic range (10 to 20,000 fmol/liter). When seroconversion panels were tested, the assay was not inferior to HCV RNA detection and reduced the preseroconversion period by 4 to 16 days. The results obtained by core antigen and HCV RNA quantification for 385 clinical specimens were correlated by regression analysis (r = 0.857), but the calculated conversion equation differed significantly from the line of identity. Monitoring of viral kinetics by use of either core antigen or RNA concentrations in 38 HCV-infected patients undergoing antiviral combination therapy resulted in very similarly shaped curves in all cases. Finally, the Architect HCV Ag assay was also shown to enable high-throughput screening of in vitro HCV RNA replication. With these results taken together, the Architect HCV Ag assay proved to be a specific, reproducible, highly sensitive, and clinically applicable test format which will find its future place in the context of virological HCV diagnostics.

Analytical evaluation of HCV core antigen and interest for HCV screening in haemodialysis patients

BACKGROUND

It is important to diagnose a hepatitis C virus infection in the acute phase in order to reduce the incidence of this infection in high-risk populations like haemodialysis patients. But detection systems for serum HCV antibodies are insensitive in the acute phase because of the long serological window. Previous studies showed that the HCV core antigen (HCV Ag) may be an alternative to HCV RNA in this context.

OBJECTIVES

To evaluate the performances of the new Abbott ARCHITECT((R)) HCV Ag test and its usefulness in screening for HCV infections in haemodialysis patients.

STUDY DESIGN

The serum HCV Ag titre was compared to the HCV RNA viral load in 98 samples from HCV-infected patients to determine the correlation between the two markers and the influence of genotype. We screened 2752 patients from 37 French haemodialysis units who tested negative for HCV antibodies using the HCV Ag and RNA assays.

RESULTS

The HCV Ag titre was correlated with the HCV RNA (Spearman test coefficient 0.9041, p<0.0001) and all genotypes and subtypes were detected. The HCV Ag and HCV RNA results agreed well for haemodialysis patients. Diagnostic specificity of HCV Ag was high (99.2%) considering HCV RNA as the reference. The two seronegative patients (of 2752) who were HCV RNA positive were also HCV Ag positive.

CONCLUSIONS

The ARCHITECT HCV Ag test is a reliable, highly specific assay for screening acute HCV infections in haemodialysis units. It is a robust alternative to HCV RNA testing.

Evaluation of hepatitis C virus core antigen assays in detecting recombinant viral antigens of various genotypes

A single substitution within the hepatitis C virus core antigen sequence, A48T, which is observed in approximately 30% of individuals infected with genotype 2a virus, reduces the sensitivity of a commonly used chemiluminescence enzyme immunoassay. Quantitation of the antigen is improved by using a distinct anticore antibody with a different epitope.

Hepatitis C virus kinetics during the first phase of pegylated interferon-alpha-2b with ribavirin therapy in patients with living donor liver transplantation

AIM

To identify the problems of pegylated interferon (PEG IFN) with ribavirin therapy against hepatitis C virus (HCV) reinfection in living donor liver transplantation (LDLT) patients. HCV kinetics during the PEG IFN with ribavirin therapy were analyzed in LDLT patients, as well as in chronic hepatitis C (CHC) patients.

METHODS

The study included 80 consecutive HCV infected patients undergoing PEG IFN with ribavirin therapy (64 CHC and 16 LDLT patients) who attended the Nagasaki University Hospital for an initial visit between January 2005 and December 2007.

RESULTS

The sustained viral response (VR) rate of the CHC group (80%) was superior to the LDLT group (22%). The viral disappearance rate of the CHC group was also superior to the LDLT group, regardless of the HCV serotype. The HCV core antigen (cAg) titer under treatment in the LDLT group was more than that of the CHC group from day 0 to week 12. The HCV cAg decrease rate of the LDLT group on the first day of treatment was less than that of the CHC group.

CONCLUSION

The HCV infection of a transplanted liver is more refractory to treatment than a non-transplanted liver. The low reduction HCV cAg rate on day 1 is one of the problems of the combination therapy.

A new sensitive and automated chemiluminescent microparticle immunoassay for quantitative determination of hepatitis C virus core antigen

A new sensitive and automated chemiluminescent assay was developed for the quantitative determination of hepatitis C virus (HCV) core antigen (Ag) in human sera or plasma: the Abbott ARCHITECT HCV Ag test. The assay sensitivity was determined by testing 10 commercial HCV seroconversion panels. Without exception, a positive result for HCV core Ag was observed before anti-HCV detection, resulting in an average reduction in the period between exposure and detection of 35.8 days. Both HCV core Ag and HCV RNA were detected in the panels at the same time, indicating equivalent sensitivity and detectability. A total of 197 HCV specimens comprising genotypes 1a, 1b, 2a, 2b, 3a, 3k, 4a, 5a and 6a were evaluated. Among these, 196 (99.5%), 191 (97%) and 193 (98%) were reactive using the HCV Ag, the immunoradiometric HCV Ag and the Amplicor HCV Monitor 2 assays, respectively. A comparison with the Amplicor HCV Monitor 2 showed a correlation coefficient (r) of 0.74. The specificity of the assay was established at 99.8% by testing 5403 specimens from US volunteer blood donors, hospitalized patients and individuals with medical conditions unrelated to HCV infection, in addition to specimens containing potentially interfering substances.

Assessment of specific antibodies to F protein in serum samples from Chinese hepatitis C patients treated with interferon plus ribavarin

The hepatitis C virus (HCV) alternate reading frame protein or F protein of the HCV 1b genotype is a double-frameshift product of the HCV core protein. In order to assess the presence of antibodies specific for F protein and their clinical relevance in sera from HCV patients, we produced recombinant F protein and core protein of the HCV 1b genotype in Escherichia coli. An enzyme-linked immunosorbent assay was developed using purified recombinant HCV core, F protein, and a 99-residue synthetic F peptide (F99). The seroprevalences of anticore, anti-F protein, and anti-F99 synthetic peptide were 95%, 68%, and 36%, respectively, in 168 HCV patients. The prevalence of anti-F antibodies did not correlate with viral load, genotype, or alanine aminotransferase level. Interferon combination therapy induced a decline in the level of anti-F antibodies in 55 responders (P < 0.01). Thirteen responders (24%) lost their anti-F recombinant protein antibodies, and 17 (31%) lost their anti-F synthetic peptide antibodies, whereas no decrease was observed for the 17 nonresponders. These changes were significant between responders and nonresponders (P < 0.05). Meanwhile, no change was found in the anticore antibody titer of the 72 treated patients. The percentage of anti-F-protein-negative patients (15/15 [100%]) who achieved a sustained virological response (SVR) was higher than that of the anti-F-positive patients (70%) (P < 0.05). Based on these findings, HCV F protein elicits a specific antibody response other than the anticore protein response. Our data also suggest that the presence and level of anti-F antibody responses might be influenced by the treatment (interferon plus ribavirin) and associated with an SVR in Chinese hepatitis C patients.

A chemiluminescent, magnetic particle-based immunoassay for the detection of hepatitis C virus core antigen in human serum or plasma

Hepatitis C virus (HCV) exposure in blood donors is determined serologically by the detection of anti-HCV antibodies in serum or plasma. However, a "window" period of 30-70 days after exposure exists where specific antibodies to HCV antigens are not detected. The use of nucleic acid testing for the detection of HCV RNA or antigen testing for the detection of HCV core protein have resulted in dramatic reductions in the pre-seroconversion window period. In this study, an automated HCV core antigen detection test was developed. This magnetic microparticle-based assay utilizes anti-HCV core monoclonal antibody to capture antigen present in human serum or plasma. Captured antigen is then detected using an anti-HCV core monoclonal antibody conjugated with a chemiluminescent compound. The specificity of this assay was established at 99% upon testing a population of normal volunteer blood donors. Sensitivity was determined by testing 16 commercially available HCV seroconversion panels representing genotypes 1a, 1b, 2b, and 3a. In each panel tested, HCV core antigen was detected prior to anti-HCV antibody, resulting in a reduction of the window period by greater than 23 days on average, and greater than 34 days on panels initially NAT negative. In addition, HCV core antigen was detected in >97% of HCV RNA positive/antibody negative specimens, exhibiting sensitivity nearly equivalent to nucleic acid testing in the pre-seroconversion window period for the panels examined.