HCV core antigen comes of age: a new opportunity for the diagnosis of hepatitis C virus infection

Single-tube, single-strip lateral flow assays utilizing loop-mediated isothermal amplification for simultaneous hepatitis B and C viral detection

Globally, hepatitis B virus (HBV) affects over 250 million people, whereas hepatitis C virus (HCV) affects approximately 70 million people, posing major public health challenges. Despite the availability of vaccines and treatments, a lack of comprehensive diagnostic coverage has left many cases undiagnosed and untreated. To address the need for sensitive, specific, and accessible diagnostics, this study introduced a multiplex loop-mediated isothermal amplification assay with lateral flow detection for simultaneous HBV and HCV testing. This assay achieved exceptional sensitivity and was capable of detecting HBV and HCV concurrently in a single tube and on a single strip within 25 min, achieving the required clinical sensitivity (10 and 103 genomic copies/reaction for HBV and HCV, respectively). The method was validated in clinical samples of various viral genotypes, achieving an equivalent limit of detection. Additionally, a custom portable heating device was developed for field use. The assay developed here, capable of direct viral detection on the strip, shows promise in supplanting current methods that solely identify antibodies and necessitate additional qPCR for viral activity assessment. This economical and rapid assay aligns with point-of-care testing needs, offering significant advancements in enhancing viral hepatitis diagnostics in settings with limited resources.

Hepatitis C virus core antigen: A diagnostic and treatment monitoring marker of hepatitis C virus in Indian population

BACKGROUND

The diagnosis and treatment monitoring of hepatitis C is quite challenging. The screening test, i.e. antibody assay, is unable to detect acute cases, while the gold standard hepatitis C virus (HCV) reverse transcriptase polymerase chain reaction (RTPCR) assay is not feasible in resource-limited countries such as India due to high cost and infrastructure requirement. European Association for the Study of the Liver and World Health Organization have approved a new marker, i.e. HCV core antigen (HCVcAg) assay, as an alternative to molecular assay. In this study, we have evaluated HCVcAg assay for diagnosis and treatment monitoring follow-up in Indian population infected with hepatitis C.

METHODS

Blood specimen of 90 clinically suspected cases of acute hepatitis C were tested simultaneously for anti-HCV antibody assay via ELISA (enzyme-linked immunoassay), HCVcAg assay by chemiluminescence immune assay (CLIA) and HCV RTPCR VL (viral load) assay. Thirty-four HCV RTPCR positive patients were further enrolled in treatment monitoring group whose blood samples were tested at the beginning of treatment, two weeks, four weeks and 12 weeks via HCV core Ag assay and HCV RTPCR Viral Load assay.

RESULTS

Considering HCV RTPCR as gold standard, diagnostic performance of HCV core Ag assay and anti-HCV antibody assay was evaluated. The sensitivity and specificity of HCV core Ag assay were higher than that of anti-HCV Antibody assay, i.e. 88.3% and 100% vs. 23.3% and 83.3%, respectively. The overall diagnostic accuracy of HCV core Ag assay was 92.20%. Among treatment follow-up group, HCV core Ag levels correlated well with HCV viral load levels, at the beginning of treatment (baseline) till 12 weeks showing highly significant Spearman rank correlation coefficient of > 0.9 with HCV viral load levels.

CONCLUSIONS

HCV core Ag assay is a cost-effective, practically feasible substitute of HCV RTPCR viral load assay for diagnosis as well as long duration treatment monitoring of hepatitis C infection in resource-limited settings.

Production and characterization of monoclonal antibodies for the detection of the hepatitis C core antigen

Background: Despite highly effective treatments to cure hepatitis C, almost 80% of chronically HCV-infected people are not treated, as they are unaware of their infection. Diagnostic rates and linkage to care must be substantially improved to reverse this situation. The HCV core antigen (HCVcAg) is a highly conserved protein that can be detected in the blood of HCV-infected patients and indicates active infection. Aim: To produce murine monoclonal antibodies against HCVcAg suitable for rapid and inexpensive tests to detect HCV infection. Methods: BALB/c mice were sequentially inoculated with purified recombinant HCVcAg from Gt1a, Gt3a, Gt4a, and Gt1b genotypes. Hybridomas producing the desired monoclonal antibodies were selected, and the reactivity of antibodies against HCVcAg from various genotypes was tested by Western blotting and dot blotting. The binding kinetics of the antibodies to purified HCVcAg was analyzed by surface plasmon resonance (SPR), and their ability to detect HCVcAg was tested by double antibody sandwich ELISA (DAS-ELISA). Results: Four specific monoclonal antibodies (1C, 2C, 4C, and 8C) were obtained. 1C, 2C, and 4C recognized HCVcAg of all genotypes tested (Gt1a, Gt1b, Gt2a, Gt3a, and Gt4a), while 8C did not recognize the Gt2a and Gt3a genotypes. Based on SPR data, the antibody-HCVcAg complexes formed are stable, with 2C having the strongest binding properties. DAS-ELISA with different antibody combinations easily detected HCVcAg in culture supernatants from HCV-infected cells. Conclusion: Specific and cross-reactive anti-HCVcAg monoclonal antibodies with strong binding properties were obtained that may be useful for detecting HCVcAg in HCV-infected samples.

Diagnostic Performance of the HCV Core Antigen Test To Identify Hepatitis C in HIV-Infected Patients: a Systematic Review and Meta-Analysis

The standard algorithm for diagnosing hepatitis C virus (HCV) infection has two steps, an HCV antibody test for screening and a nucleic acid amplification test (NAAT) for confirmation. However, the HCV core antigen (HCVcAg) detection assay is an alternative for one-step diagnosis. We aimed to evaluate the diagnostic performance of the Abbott ARCHITECT HCV Ag assay to detect active hepatitis C in serum/plasma in people living with HIV/AIDS (PLWHA), through a systematic review and meta-analysis. PubMed, EMBASE, Scopus, Web of Science, and the Cochrane Library were searched until 20 September 2022 (PROSPERO, CRD42022348351). We included studies evaluating Abbott ARCHITECT HCV Ag assay (index assay) versus NAATs (reference test) in PLWHA coinfected with HCV who did not receive antiviral treatment for HCV. Meta-analysis was performed with the MIDAS module using Stata and random-effects models. The QUADAS-2 tool evaluated the risk of bias. The bivariate analysis was conducted on 11 studies with 2,407 samples. Pooled sensitivity was 0.95 (95% CI = 0.92 to 0.97), specificity 0.97 (95% CI = 0.93 to 0.99), positive likelihood ratio 37.76 (95% CI = 12.84 to 111.02), and negative likelihood ratio 0.06 (95% CI = 0.04 to 0.09). The area under the curve was 0.97 (95% CI = 0.20 to 1.00). For low prevalence (≤5%), the posttest probability that an individual with a positive test was a true positive ranged from 4% to 67%, whereas, at high prevalence (≥10%), the posttest probability was between 81% and 87%, indicating that a confirmatory test should be necessary, particularly with prevalence values of ≤1%. Regardless of prevalence, the probability that an individual with a negative test was a false negative was close to zero, indicating that the individual was not infected with HCV. In conclusion, the accuracy of the Abbott ARCHITECT HCV Ag assay was very good for HCV screening in serum/plasma samples from PLWHA. The clinical utility to confirm HCV infection was acceptable in high-prevalence settings (≥10%) but poor in low-prevalence settings (≤1%). Furthermore, it was excellent in excluding active HCV infection.

Comparing RT-qPCR and Hepatitis C Virus Antigen Detection Assay for Detecting Active Infection in Blood Donors in Fars Province, Iran

Background: Immunoassay is still used to detect hepatitis C virus (HCV) antibodies in donated blood in many developing countries. However, an immunoblotting confirmation test is needed to confirm positive results. Objectives: We compared the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of nucleic acid testing and HCV core antigen (HCVcAg) detection in the serum samples of blood donors with HCV antibodies to determine active infection. Methods: Overall, 90 serum samples from blood donors referred to Fars Blood Transfusion Organization, Iran during March 2017-March 2019 and initially tested for HCV antibodies were included in the study. Enzyme immunoassays were used to detect the HCV antigen and anti-HCV antibody. A commercial reverse transcription-polymerase chain reaction (RT-PCR) kit was used to quantify HCV RNA. The HCV genotypes were also determined by DNA sequencing. In order to compare the HCVcAg detection method with the RT-qPCR reference method, sensitivity, specificity, performance, PPV, and NPV were calculated. Results: Out of 90 serum samples, 73 were positive for anti-HCV antibody, and 17 sera were negative. The HCV RNA was detected in 60 (82%) of anti-HCV antibody-positive samples, whereas the HCVcAg test detected HCV antigen in 54 (74%) of the samples, indicating a significant correlation between the two assays (r = 0.86). The overall sensitivity and specificity for HCVcAg detection method were 93.85% [95% confidence interval (CI): 84.99 - 98.3%] and 100% (95% CI: 94.64 - 100%), respectively. Based on the statistical analysis, the accuracy of the antigen detection test was 94.83% (95% CI: 87.26 - 98.58%). Moreover, the agreement between HCV RNA detection using RT-qPCR and HCVcAg detection was 97.78% (kappa value: 0.94). Conclusions: The sensitivity and specificity of HCVcAg detection in blood donors were ideal compared to the RT-qPCR reference method. However, the method should be tested on more HCV antibody-positive and -negative samples. Furthermore, our study revealed a significant association between the number of RT-qPCR-positive cases and the cases diagnosed by the HCVcAg detection method for screening and detecting active HCV infection in blood donors.

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.

HCV Core Protein Induces Chemokine CCL2 and CXCL10 Expression Through NF-κB Signaling Pathway in Macrophages

HCV core protein is the first structural protein synthesized during hepatitis C virus (HCV) infection and replication. It is released from virus infected liver cells and mediates multiple functions to affect host cell response. The innate immune response is the first line of defense against viral infection. After HCV infection, Kupffer cells (KCs) which are liver macrophages play an important role in host innate immune response. Kupffer cells act as phagocytes and release different cytokines and chemokines to counter viral infection and regulate inflammation and fibrosis in liver. Earlier, we have demonstrated that HCV core protein interacts with gC1qR and activates MAPK, NF-κB and PI3K/AKT pathways in macrophages. In this study, we explored the effect of HCV core protein on CCL2 and CXCL10 expression in macrophages and the signaling pathways involved. Upon silencing of gC1qR, we observed a significant decrease expression of CCL2 and CXCL10 in macrophages in the presence of HCV core protein. Inhibiting NF-κB pathway, but not P38, JNK, ERK and AKT pathways greatly reduced the expression of CCL2 and CXCL10. Therefore, our results indicate that interaction of HCV core protein with gC1qR could induce CCL2 and CXCL10 secretion in macrophages via NF-κB signaling pathway. These findings may shed light on the understanding of how leukocytes migrate into the liver and exaggerate host-derived immune responses and may provide novel therapeutic targets in HCV chronic inflammation.

Evaluation of Hepatitis C Virus Core Antigen Assay in a Resource-Limited Setting in Pakistan

The diagnosis of Hepatitis C virus (HCV) infection can be challenging due to its cost and a lack of access to centralized testing. There is an urgent need to develop simplified HCV testing algorithms. The aim of this study was to evaluate the performance characteristics of a Hepatitis C core antigen (HCVcAg) assay in a decentralized, resource-limited setting. This is a descriptive cross-sectional study from a highly endemic area of Karachi, Pakistan. Between October 2019 and July 2020, subjects aged 12 years and above who screened positive for HCV antibodies were simultaneously tested for HCV RNA (Xpert HCV Viral Load, GeneXpert^® IV, Cepheid, France) and HCVcAg (ARCHITECT HCV Ag assay, Abbott^® Diagnostics) to confirm active HCV infection. An Abbott ARCHITECT^® i1000SR Immunoassay Analyser was installed at a local district hospital as a point-of-care (POC) facility for HCVcAg testing, while samples for HCV RNA were tested in a central lab. Two hundred individuals (mean age 46.4 ± 14.5 years, 71.5% females), who screened positive for HCV antibody, were included in the study. HCV RNA was detected in 128 (64.0%) while HCVcAg was reactive in 119 (59.5%) cases. Performance of the Immunoassay Analyser was excellent with a higher throughput and quicker readout value compared to the GeneXpert System. The sensitivity and specificity of HCVcAg (≥10 fmol/L) at HCV RNA thresholds of ≥12 was 99.1% (95% CI: 95–100%) and 87.6% (95%CI: 78.4–94%). A strong agreement was observed between the HCVcAg assay and HCV RNA. The ARCHITECT HCV Ag assay showed high sensitivity and specificity compared to HCV RNA in a decentralized, resource-limited setting. It can therefore be used as a confirmatory test in HCV elimination programs, particularly for low-income countries such as Pakistan.

Utility of hepatitis C virus core antigen testing for diagnosis and treatment monitoring in HCV infection: A study from India

PURPOSE

The major bottleneck in most developing countries to attain the WHO goal of eliminating hepatitis C as a public health threat by 2030 is the limited access to molecular testing and loss of infected patients to follow up. Many of the hepatitis C virus (HCV) infected patients fail to get the confirmatory HCV RNA test done after initial screening for anti-HCV antibody. The hepatitis C core antigen (HCVcAg) chemiluminescence-based assay which is newly introduced in the Indian health setup could prove to be a potential marker in the single-point screening and confirmation of HCV infection. This study was done to evaluate the performance of the HCVcAg assay for diagnosis and treatment monitoring of patients with HCV infection.

METHODS

In this retrospective study 208 archived plasma samples from 184 patients were retrieved and all three markers for the laboratory diagnosis of HCV infection, anti-HCV, HCV RNA and HCVcAg were performed in a single freeze thaw cycle. For a subset of patients (n ​= ​24), paired samples, baseline samples and samples collected at 12 weeks after completion of treatment (SVR12) were available.

RESULTS

The sensitivity and specificity of the HCVcAg assay were 91.58% and 99.12% respectively with HCV RNA as the gold standard for the detection of active infection. There was a strong correlation between HCVcAg and HCV RNA (R ​= ​0.85, p ​< ​0•0001). Among the paired samples, the concordance between the HCVcAg and HCV RNA at baseline and at SVR12 was 95.8%.

CONCLUSION

The HCVcAg assay showed a good correlation with the gold standard HCV RNA assay, especially in the case of treatment naïve patients. Thus, the use of HCVcAg assay as tool for testing and confirmation of HCV infection has the potential to increase the uptake of HCV testing.

Village-to-village screening for hepatitis B and C using quantitative HBsAg and anti-HCV testing with reflex HCV core antigen tests in the remote communities of a resource-rich setting: a population-based prospective cohort study

OBJECTIVES

Community-based screening for hepatitis B virus (HBV) and hepatitis C virus (HCV) is essential for hepatitis elimination. This study attempted to increase screening accessibility and efficacy by using alternative tools.

DESIGN

Population-based prospective cohort study.

SETTING

Hepatitis elimination program at Yunlin County, Taiwan.

PARTICIPANTS

All 4552 individuals participated in 60 screening sessions of a community-based HBV and HCV screening project in five rural townships with approximately 95 000 inhabitants in central-western Taiwan.

INTERVENTIONS

To increase accessibility, 60 outreach screening sessions were conducted in 41 disseminative sites. Quantitative HBV surface antigen (qHBsAg) and anti-HCV testing with reflex HCV core antigen (HCV Ag) tests were employed as alternative screening tools.

MAIN OUTCOME MEASURES

Calculate village-specific prevalence of HBsAg, anti-HCV and HCV Ag and establish patient allocation strategies according to levels of qHBsAg HCV Ag and alanine aminotransferase (ALT).

RESULTS

Of 4552 participants, 553, 697 and 290 were positive for HBsAg, anti-HCV and HCV Ag, respectively; 75 of them had both HBsAg and anti-HCV positivity. The average (range) number of participants in each screening session was 98 (31-150). The prevalence rates (range) of HBsAg, anti-HCV and HCV Ag were 12.1% (4.3%-19.4%), 15.3% (2.6%-52.3%) and 6.4% (0%-30.2%), respectively. The HCV Ag positivity rate among anti-HCV-positive participants was 42% (0%-100%). Using cut-off values of >200 IU/mL for qHBsAg, >3 fmol/L for HCV Ag and >40 IU/mL for ALT as criteria for patient referral, we noted an 80.2% reduction in referral burden. Three villages had high anti-HCV prevalences of 52.3%, 53.8% and 63.4% with corresponding viraemic prevalences of 23.2%, 30.1% and 22% and thus constituted newly identified HCV-hyperendemic villages.

CONCLUSION

Outreach hepatitis screening increases accessibility for residents in rural communities. Screening HBV and HCV through qHBsAg and HCV Ag tests provides information concerning viral activities, which might be conducive to precise patient allocation in remote communities.

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.

The prevalence of HCV RNA positivity in anti-HCV antibodies-negative hemodialysis patients in Thrace Region. Multicentral study

Introduction

HCV infection in patients under hemodialysis for end stage chronic kidney disease (ESCKD) may exist despite the absence of anti-HCV antibodies. Molecular methods are widely accepted as "gold standard" techniques for the detection of viral RNA. However, the molecular methods are more expensive in comparison to conventional methods and their replacement is not cost-effective. The aim of this study was to estimate the prevalence of HCV RNA positivity in anti-HCV negative hemodialysis patients and evaluate new diagnostic methods for the detection and the monitoring of hepatitis C in ESCKD patients.

Methods

The study was performed in four hospitals of Thrace region of Greece and 233 patients with no history of hepatitis C were enrolled. Measurement of anti-HCV antibodies and HCV core antigen was performed by microparticle chemiluminescence immunoassay. Molecular detection of viral RNA was performed by the real-time RT PCR.

Results

The mean age of the patients was 64.9 ± 23.3 years. HCV-Ag was positive in 2/233 patients (0.86%). Nevertheless, viral RNA was negative in those patients.

Conclusions

The results of the present study showed that the incidence of HCV-RNA in patients with negative anti-HCV Abs, in hemodialysis patients in Thrace region of Greece was negligible (0/233).

Hepatitis C virus core antigen as alternative diagnostic algorithm for active hepatitis C virus infection among haemodialysis population: Cost implications

AIMS

In Malaysia, majority anti-HCV positive haemodialysis patients do not undergo hepatitis C confirmation due to the high cost of HCV RNA. HCV Core Antigen might be a cost-effective diagnostic test to identify HD patients who have active HCV infection eligible for Direct Acting Anti-viral therapy.

METHODS

A cross-sectional study was conducted to assess the correlation between HCV Ag and HCV RNA and the cost implications of different diagnostic algorithms to diagnose active HCV infection using Anti-HCV, HCV Ag, and HCV RNA. Pre-dialysis blood was tested for both HCV Ag and HCV RNA. HCV Ag was tested with Abbott ARCHITECT HCV Ag test.

RESULTS

Two-hundred twenty-seven haemodialysis patients were recruited from 20 centres with mean age of 57.68 ± 12.48 years, and male constitutes 56.8% (129) of the study population. HCV Ag correlated well with HCV RNA (Spearman test coefficient 0.943, p < .001) with sensitivity of 93.9%, specificity 99.3%, and the accuracy was 97.36%. Cost analysis indicated that a sequential test involving Anti-HCV antibody as initial screening, followed by HCV Ag on Anti-HCV positive and HCV RNA on HCV Ag negative cases translated to a modest cost-saving algorithm compared to standard diagnostic algorithm.

CONCLUSION

HCV Ag correlated well with HCV RNA and can potentially be fused in an alternative diagnostic algorithm to generate cost savings methods to diagnose active HCV infection among haemodialysis patients. This alternative algorithm is especially relevant in low to middle-income countries such as Malaysia to optimize the use of the healthcare resource and gains in clinical outcomes.

Hepatitis C core antigen testing to diagnose active hepatitis C infection among haemodialysis patients

Background

Hepatitis C virus (HCV) infects more than 71 million people worldwide and chronic HCV infection increases the risk of liver cirrhosis and failure. Haemodialysis (HD) is one of the renal replacement therapies with risk of HCV transmission. Anti-HCV antibodies are the serological screening test for HCV infection that does not detect active phase of infection. Majority HCV infected HD patients in Malaysia do not have further HCV RNA performed due to high cost and thus HCV treatment is less frequently offered. HCV Core Antigen (HCV Ag) can potentially be used to diagnose active HCV infection in HD population in comparison to HCV RNA, at lower cost.

Methods

We conducted a cross-sectional study to assess the correlation between HCV Ag and HCV RNA and to identify the prevalence of active HCV infection among HCV seropositive HD patients from dialysis centres across West Malaysia from July 2019 to May 2020. Pre-dialysis blood was taken and tested for both HCV Ag and HCV RNA tests. HCV Ag was tested with Abbott ARCHITECT HCV Ag test.

Results

We recruited 112 seropositive HD patients from 17 centres with mean age of 54.04 ± 11.62 years, HD vintage of 14.1 ± 9.7 years, and male constitute 59.8% (67) of the study population. HCV Ag correlates well with HCV RNA (Spearman test coefficient 0.833, p < 0.001). The sensitivity was 90.7%, specificity 100%, positive predictive value (PPV) 100%, negative predictive value (NPV) 76.5%, and accuracy 92.9%. For HCV RNA level > 3000 IU/mL, HCV Ag had a higher sensitivity of 95.1% and greater correlation (Spearman test coefficient 0.897, p < 0.001). The prevalence of active HCV infection was 76.8% among HCV seropositive HD patients.

Conclusions

Although HCV Ag is less sensitive, it shows an excellent correlation with HCV RNA and has 100% PPV. HCV Ag can be considered as an alternative diagnostic tool for chronic active HCV infection among HD cohort, who can then be considered for HCV treatment. For seropositive HD patient with negative HCV Ag, we recommend to follow-up with HCV RNA test.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-020-02154-4.

Feasibility of anti-HCV reflex HCV Ag screening strategy in an HCV endemic community

BACKGROUND/PURPOSE

The HCV core antigen (HCV Ag) assay displays high sensitivity and strong correlation with HCV RNA. However, the feasibility of anti-HCV reflex HCV Ag screening in a community-wide setting is rarely discussed.

METHODS

We performed a two-phase community-based hepatitis C screen in an HCV-prone area of central Taiwan. During the training phase, all participants were test for anti-HCV, HCV Ag and HCV RNA to validate sensitivity, specificity, and accuracy of HCV Ag. During the validation phase, an anti-HCV reflex HCV Ag screen was conducted based on the results of training phase. Outcomes of the study were presented as positive and negative predictive values (PPV and NPV).

RESULTS

Of 935 training phase participants, the rate of positive anti-HCV and HCV Ag were 175 (18.7%) and 78 (8.3%), respectively. Test sensitivity, specificity, and accuracy of HCV Ag were 97.1%, 98.6%, and 97.8%, respectively. During validation phase, only anti-HCV-positive serum samples were tested for HCV Ag. Of 1932 participant, 285 (14.8%) were anti-HCV-positive. 133 (46.7%) of the 285 anti-HCV-positive samples were HCV Ag-positive. PPV and NPV were 98.4% and 99.3%, respectively. Across the entire participant sample, a significant linear correlation between HCV Ag and HCV RNA concentration was noted (r² = 0.93, p-value<0.001) following log-log transformation.

CONCLUSION

Anti-HCV reflex HCV Ag screening is a feasible strategy for aiding HCV-prone communities.

Evaluation of a hepatitis C virus core antigen assay from venepuncture and dried blood spot collected samples: A cohort study

The global scale-up of hepatitis C virus (HCV) diagnosis requires simplified and affordable HCV diagnostic pathways. This study evaluated the sensitivity and specificity of the HCV Architect core antigen (HCVcAg) assay for detection of active HCV infection in plasma and capillary whole blood dried blood spots (DBS) compared with HCV RNA testing in plasma (Abbott RealTime HCV Viral Load). Samples were collected from participants in an observational cohort enrolled at three sites in Australia (two-drug treatment and alcohol clinics and one homelessness service). Of 205 participants, 200 had results across all samples and assay types and 186 were included in this analysis (14 participants receiving HCV therapy were excluded). HCV RNA was detected in 29% of participants ([95% CI: 22.6-36.1], 54 of 186). The sensitivity of HCVcAg for detection of active HCV infection in plasma was 98.1% (95% CI: 90-100) and 100% (95% CI: 93-100) when compared to HCV RNA thresholds of ≥12 and ≥1000 IU/mL, respectively. The sensitivity of the HCVcAg assay for detection of active HCV infection in DBS was 90.7% (95% CI: 80-97) and 92.5% (95% CI: 82-98) when compared to HCV RNA thresholds of ≥12 and ≥1000 IU/mL, respectively. The specificity of HCV core antigen for detection of active infection was 100% (95% CI: 97-100) for all samples and RNA thresholds. These data indicate that the detection of HCVcAg is a useful tool for determining active HCV infection; to facilitate enhanced testing, linkage to care and treatment particularly when testing plasma samples are collected by venepuncture.

Community screening for hepatitis C virus infection in a low-prevalence population

BACKGROUND

Age cohort screening for hepatitis C virus (HCV) might be an effective strategy if the majority of undiagnosed cases are concentrated in a particular age group. The objective of this study was to determine HCV prevalence in different age cohorts of the general population in the Central European part of Russia and second, to assess feasibility of HCV antigen testing for community screening programs.

METHODS

Sera from 2027 volunteers were tested for anti-HCV (Architect Anti-HCV, Abbott Laboratories). All anti-HCV reactive samples were confirmed in an immunoblot and tested for HCV Ag (ARCHITECT HCV Ag, Abbott Laboratories), HCV RNA and HCV viral load.

RESULTS

Out of 31 individuals with anti-HCV reactive result, 22 (71%) were confirmed by immunoblot, six were false positives and three were indeterminate. Active infection was observed in 73% of anti-HCV confirmed positives. Five out of 16 individuals had low HCV-RNA levels (< 10,000 IU/mL) and one of those had a very low level (594 IU/mL). Agreement between HCV Ag and HCV RNA was 100%. Total anti-HCV and active HCV infection rates were 1.09% (22/2027) and 0.79% (16/2027), respectively. The peak rates were observed in people 60 years or older (anti-HCV: 2.84% [95% CI: 1.66-4.74%], 13/319; HCV RNA/HCV Ag: 2.23% [95% CI: 1.20-4.00%], 10/319).

CONCLUSIONS

Overall HCV prevalence is low, except in people 60 years or older. The latter should be considered as a target group for HCV screening. The high agreement between HCV RNA and HCV Ag suggests the utility of HCV Ag testing to confirm active infection in screening programs.

Streamlining the screening cascade for active Hepatitis C in Russia: A cost-effectiveness analysis

OBJECTIVE

Screening for hepatitis C in Russia is a complex process that involves several visits and stepwise testing, limiting adherence and substantially reducing the yield in the identification of active infections. We aimed to evaluate the cost-effectiveness of different screening algorithms from a health system perspective.

METHODS

A decision analytic model was applied to a hypothetical adult population eligible to participate in a general screening program for hepatitis C in Russia. The standard pathway (I: Screen for anti-HCV antibodies followed by a nucleic acid test for HCV RNA on antibody positives) was compared to three alternatives (II: Screen for antibodies, a reflexed test for HCV antigen on antibody positives, and RNA on antigen negatives; III: Screen for antibodies, a reflexed test for HCV antigen on antibody positives; IV: Screen for antigen). Each strategy considered a cascade of events (referral, adherence, testing, diagnosis) that must occur for screening to be effective. The primary measure of effectiveness was the number of diagnosed active infections. Calculations followed a health system perspective with costs derived from 2017 reimbursement rates and a willingness-to-pay of 2,000RUB ($82) per diagnosed active infection. Model was tested with deterministic and probabilistic sensitivity analyses.

RESULTS

Non-adherence to screening stages reduced the capture rate of active infections in Strategy I from 79.0% to 40.6%. Strategies II, III, and IV were less affected and identified 69%, 67%, and 104% more infections. Average costs per diagnosed infection were decreased by 41% from 89,599RUB ($3,681) for I to 53,072RUB ($2,180), 53,004RUB ($2,177), and 59,633RUB ($2,450) for II, III, and IV, respectively. With a probability of 97%, Strategy III was most cost-effective with an incremental cost-effectiveness ratio vs. I of -1,373RUB (CI: -5,011RUB to -2,033RUB; $-56; CI: -$206 to -$84). Below a willingness-to-pay of 91,000RUB ($3,738), Strategy IV was not cost-effective. Sensitivity analyses confirmed the robustness of results.

CONCLUSIONS

Testing strategies for hepatitis C with HCV antigen on HCV antibody positive cases offer a streamlining opportunity for population screening programs. Those shall increase the chances for detecting active infections and are cost-effective over current practice in Russia.