Core Antigen Testing Research Articles

Performance evaluation of the Abbott Alinity Hepatitis C antigen next assay in a US urban emergency department population

IntroductionHCV antibody assays have been used to screen for HCV, but confirmation of acute infection is dependent on RNA or core antigen testing. The aim of the study was to compare the performance of five HCV test methods, including RNA testing, on a US emergency department population. MethodsClinical performance metrics were calculated on 708 consenting Johns Hopkins Emergency Department patients who self-reported an increased risk for HCV infection. Detection times of antibody, antigen, and RNA testing were compared using 89 samples from commercially available seroconversion panels. Testing was performed on the Abbott Alinity HCV Ag Next (RUO), Roche Elecsys HCV Duo, Abbott ARCHITECT Anti-HCV, and Elecsys Anti-HCV II assays. RNA testing was performed on the Abbott m2000 system. ResultsOverall, 21 (3.0%) participants tested positive for HCV on at least one test, 11 (52.4%) had chronic, 1 (4.8%) had an acute, and 3 (14.3%) had resolved infections. The Alinity HCV Ag Next assay demonstrated 99.43% specificity when compared to RNA testing. The Alinity HCV Ag Next assay also detected 91.67% of the active infections compared to RNA testing, while the Elecsys HCV Duo Ag assay detected only 58.33%. The seroconversion panel testing demonstrated that the Alinity HCV Ag Next assay detects an infection within 0.8 days of an RNA result. ConclusionThe Alinity HCV Ag Next assay demonstrated excellent concordance to RNA testing in a US urban E.D. population. This data supports the utility of Alinity HCV Ag Next in diagnosis of active HCV infections.

A novel test and treat program for hepatitis C virus infection utilizing HCV core antigen testing, among police and general population, Islamabad, Pakistan, 2022.

Hepatitis C virus core antigen (HCVcAg) testing can simplify and decrease costs of HCV infection confirmation compared to molecular testing (nucleic acid testing). We piloted HCVcAg testing for the confirmation of active infection. The study was conducted during June through December 2022 among the police and the general population of Islamabad, Pakistan age 18 years and older. Initial screening for HCV antibody was conducted using a rapid diagnostic test (RDT) for all consenting participants. Those who tested positive had venous blood samples tested for HCVcAg, platelets and aspartate aminotransferase (AST). Persons with HCVcAg values ≥3 fmol/L were defined as viremic, and they were offered treatment with direct acting antiviral (DAA) medications, sofosbuvir and daclatasvir. Aspartate aminotransferase to platelet ratio index (APRI) was calculated for each HCV infected person, and those with an APRI score <1.5 received treatment for 12 weeks, while those with APRI ≥ to 1.5 received 24 weeks of treatment. A total of 15,628 persons were screened for anti-HCV using RDT and 643 (4.1%) tested positive. HCVcAg values of ≥3 fmol/L was found in 399/643 (62.1%), and all were offered and accepted treatment. Of those treated, 273/399 (68.4%) returned for a follow-up SVR and HCVcAg was not detected in 261/273, a 95.6% cure rate. The pilot study demonstrated the effectiveness of reaching and treating an urban population using RDT for screening and HCVcAg for confirmation of infection and test of cure.

Performance of HCV core antigen and PCR testing in a predominantly genotype 3 population.

Hepatitis C core antigen (HCVcAg) is becoming increasingly recognized as an alternative to molecular testing for the confirmation of chronic hepatitis C. However, there are limited data on the performance of this assay in a genotype 3 (GT3) predominant country like Pakistan. We conducted a study to evaluate the diagnostic performance of HCVcAg against the HCV polymerase chain reaction (PCR) molecular test. HCV antibody-positive patients requiring confirmatory testing were recruited from August to October 2018 at the Pakistan Kidney and Liver Institute and Research Center (PKLI&RC), Lahore, Pakistan. Patients with previously known diagnoses or treatment histories were excluded. The Abbott HCV Ag assay was used for HCVcAg testing. Results ≥3.00 fmol/L were considered positive for HCVcAg. The Abbott RealTime HCV assay was used for PCR testing with a lower detection limit of ≥12 IU/mL. We computed the sensitivity, specificity and correlation of HCVcAg against HCV PCR. A total of 394 patients were recruited. The median age of the patients was 42 years. Most participants were females (51.5%, n = 203), 30.7% (n = 121) had HTN, 10.4% DM (n = 41) and 5% had APRI ≥2. The overall sensitivity was 98.0% and the specificity was 98.6%. The lowest detection limit of cAg was an HCV RNA value of 4657 IU/mL. The levels of cAg were highly correlated with those of HCV RNA by Spearman's rank correlation test (r = 0.935, p < .001). HCVcAg represents a suitable alternative with high sensitivity and specificity compared with HCV PCR in the GT3-predominant population and can be incorporated into algorithms to improve linkage to care.

Opportunities for Enhanced Prevention and Control of Hepatitis C Through Improved Screening and Testing Efforts.

An estimated 2.4 million people in the United States are living with hepatitis C virus (HCV) infection. In 2020, the Centers for Disease Control and Prevention updated hepatitis C screening recommendations to test adults aged ≥18 years at least once in a lifetime and pregnant persons during each pregnancy. For those with ongoing exposure to HCV, periodic testing is recommended. The recommended testing sequence is to obtain an HCV antibody test and, when positive, perform an HCV RNA test. Examination of HCV care cascades has found that incomplete HCV testing occurs when a separate visit is required to obtain the HCV RNA test. Hepatitis C core antigen testing has been shown to be a useful tool for diagnosing current HCV infection in some settings. Hepatitis C testing that is completed, accurate, and efficient is necessary to achieve hepatitis C elimination goals.

Lessons Learned From Global Hepatitis C Elimination Programs.

In 2016, the World Health Organization introduced global targets for the care and management of hepatitis C virus (HCV) infection to eliminate hepatitis C as a public health threat by 2030. Despite significant improvements in testing and treatment, in 2020 only 23% of all persons infected with HCV globally were diagnosed. We explore examples from global hepatitis C programs in Georgia, Rwanda, and Nigeria that have used decentralized and integrated models to increase access to HCV testing. Georgia established the world's first national hepatitis C elimination program in 2015. In 2022, 2.6 million people (80% of the adults) have been screened for antibodies for HCV infection, and 80 000 persons with HCV RNA detected were treated. To achieve these results, Georgia implemented HCV core antigen testing, utilization of point-of-care (POC) HCV RNA testing, and simplification of HCV viremia detection by qualitative HCV RNA testing. Rwanda was the first country in sub-Saharan Africa to commit to HCV elimination in 2018, and as of 2022 it has achieved its screening target of 7 million people and initiated approximately 60 000 patients on hepatitis C treatment by rapid decentralization and integration of HCV services. In Nigeria, the integrated near-POC testing approach in Nasarawa State has been effective in expanding access to HCV viremia testing and enabling the possibility of same-day testing and treatment initiation. Examples of decentralization and integration of HCV testing and linkage to care in Georgia, Rwanda, and Nigeria could help inform effective strategies to reach 2030 hepatitis C elimination goals in other countries.

Evaluation of the Correlation of HCV Core Antigen Levels with HCV RNA Levels in the Diagnosis and Treatment Follow-up of Hepatitis C Virus Infections

Hepatitis C virus (HCV) infections are an important public health issue across the world because of the high risk of chronicity potential, impossibility of protection by vaccination and serious complications such as hepatocellular carcinoma. The aim of this study was to evaluate the correlation of HCV core antigen test with HCV RNA in the diagnosis and treatment follow-up and to discuss the status of being an alternative test in routine use. In the first step of the study, the compatibility of the methods was investigated by applying the HCV core antigen test to 600 serum samples from patients with pre diagnosis of HCV infection for whom anti-HCV and HCV RNA tests were routinely studied in the molecular microbiology laboratory of medical microbiology department between December 2016 and December 2018. In the second step, in addition to the routine HCV RNA test, HCV core antigen test was studied in serum samples taken before the start of the treatment, at the eighth week of the treatment and at the end of the treatment of 150 patients whose treatment were decided by the gastroenterology department within this period. The correlation between the two tests was evaluated during the treatment follow-up. Forty-nine of 600 patients were diagnosed according to test results. In 28 patients, HCV core antigen was positive in addition to HCV RNA and anti-HCV which were routinely studied. The sensitivity of HCV core antigen test was 91.49%, specificity was 100%, PPD was 100%, NPD was 97.30%, accuracy was 87.76%. There was a high correlation between HCV RNA and HCV core antigen results. In the second step of the study, sensitivity (96.52%), specificity (95.28%), PPD (95.11%), NPD (95.80%) and accuracy (92.58%) of the HCV core antigen test were determined. These results show that there is a high correlation between the two tests and that HCV core antigen test can be used as an alternative test to HCV RNA test as it is an easily applicable and cost effective test during diagnosis and treatment follow-up.

Evaluation of Quantitative Hepatitis C Virus Core Antigen Testing as a Tool for Screening and Confirmation of HCV Infection.

Hepatitis C is a common viral infection worldwide. Finding the most effective diagnostic methods with low cost is always needed for laboratory improvement. In this study, we evaluated the performance of a quantitative chemiluminescent hepatitis C virus core antigen (HCV cAg) test by comparing it with the HCV confirmatory antibody line immunoblot assay (HCV Ab-LIA) test as well as the HCV quantitate reverse transcription-polymerase chain reaction (qRT-PCR) test. A total of 394 samples were enrolled in the retrospective study. Of these, 225 samples were tested using HCV Ab screening and confirmatory Ab-LIA along with chemiluminescent HCV core Ag testing, while 169 samples were tested using qRT-PCR for HCV RNA and chemiluminescent HCV core Ag testing. Out of these, 225 positive samples tested by HCV Ab screening test were analyzed using the confirmatory Ab LIA and HCV cAg assays, a total of 183 samples (81.3 %) were confirmed to be Ab-positive, and among those, 77 samples (42.1%) were also positive for HCV cAg. Thirty-eight samples (20.76%) were HCV Ab indeterminate, and all of them were HCV cAg negative. Four samples (1.8%) were HCV Ab LIA-negative and negative for HCV cAg. Moreover, 169 samples were measured for qRT-PCR HCV viral load and quantitative HCV cAg test. One hundred and three samples were positive for HCV RNA, while 66 were negative. Among the positives, 96/103 samples were HCV cAg positive and 7/103 samples were negative. Out of the negatives, 4/66 samples were HCV cAg positive but 62/66 samples were negative. The HCV cAg results were concordant with the qRT-PCR results in 158 samples (93.5%); however, 11 samples (6.5%) were found to be discrepant. The sensitivity, specificity, positive predictive value, and negative predictive value of the quantitative HCV cAg were found to be 93%, 94%, 96%, and 90%, respectively. The overall coefficient of correlation between the HCV RNA levels and HCV cAg data was determined to be r2 = 0.9. The HCV cAg test showed a high correlation with the HCV RNA levels and may potentially be used as a more cost-effective alternative to the HCV RNA qRT-PCR test.

HCV Core-antigen Assay as an Effective Alternative to HCV RNA Quantification in Patients With Hepatitis C.

Hepatitis C virus (HCV) core antigen (Ag) test has been increasingly applied as an effective alternative to conventional molecular tests allowing rapid and affordable diagnosis, which is of paramount relevance to achieve global elimination of HCV infection. ARCHITECT® HCV Ag test was evaluated in comparison with HCV RNA quantification test (CAP/CTM) to calculate its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and to determine their correlation level. Its performance, according to low and high viral load values and in different treatment stages [during treatment (T), at the end of the therapeutic protocol (EOT) and when sustained virological response (SVR) was evaluated]. In total, 145 samples were included. Considering CAP/CTM, the sensitivity, specificity, PPV and NPV of the HCV-Ag test were 88.9%, 99.1%, 97.0% and 96.4%, respectively, and the correlation among tests was high (r=0.890), with only five discordant results. A decrease in sensitivity was found for low viral load values (<1,000 IU/ml), but the opposite was verified for high viral concentrations (≥1,000 IU/ml). A good agreement was verified for the T and EOT groups (k=0.789 and k=0.638) and an excellent agreement in the SVR group (k=1.000). HCV-Ag seems to be an effective alternative that can be routinely combined with other faster and more accessible tests (e.g., HCV antibody tests) for the identification of new HCV infections in suspected patients, eventually reserving the molecular techniques for samples with discordant results.

Antiviral Therapeutic Monitoring: Role of Hepatitis C Virus Core Antigen versus Hepatitis C Virus RNA by Polymerase Chain Reaction

Objective: To study the association between hepatitis C virus viral load by real-time PCR and core antigen value of HCV and define an antiviral treatment monitoring cut-off value for HCV core antigen.&#x0D; Study Design: Cross-sectional validation study.&#x0D; Place and Duration of Study: Department of Infectious Diseases, Chughtai Lab Lahore Pakistan, from Jun 2017 to Mar 2018. Methodology: To establish the association between these two parameters, we took a hundred positive plasma samples for HCV RNA and subjected them to an HCV Core antigen test. Furthermore, the samples were divided into three categories based on their viral load; &lt;2000 IU/ml, 2000-10,000 IU/ml and &gt;10000 IU/ml.&#x0D; Results: Our results showed that the hepatitis C virus core antigen was concordant with hepatitis C virus RNA by PCR when the viral load was above 2000 IU/ml. Below the HCV RNA load of 2000 IU/ml, the HCV core antigen had a sensitivity of 94.95% and specificity of 88.89%.&#x0D; Conclusion: In patients having a viral load above 2,000 IU/ml, the hepatitis C virus core antigen value can be used as a marker for diagnosis and monitoring antiviral therapy. After the antiviral treatment, HCV RNA real-time PCR should be performed to validate viral clearance.

High false discovery rate of the Architect anti-HCV screening test in blood donors in Uganda and evaluation of an algorithm for confirmatory testing.

Adequate supplies of donor blood remain a major challenge in sub-Saharan Africa. This is exacerbated by a lack of confirmatory testing for transfusion-transmitted infections by blood transfusion services (BTS), leading to significant blood disposal owing to putatively high seroprevalence rates amongst Ugandan blood donors. We aimed to ascertain the false discovery rate of the Architect anti-hepatitis C virus (HCV) screening assay and categorize screen-reactive samples into three groups: presumed false positive, active and past infection, and develop an algorithm for confirmatory testing. A total of 470 screen-reactive HCV blood donations were retested using the Architect anti-HCV assay, an alternative antibody test (SD Biosensor) and a core antigen (cAg) test. signal-to cut-off (S/CO) ratios and pre-analytical factors (centrifugation speed, haemolysis check, time between collection and testing) were recorded. Based on the S/CO ratio evaluation, we propose a testing algorithm to guide supplemental tests. The false discovery rate of the Architect anti-HCV assay was 0.84 as 395/470 (84%) screen-reactive samples had no evidence of HCV infection (SD Biosensor and cAg negative) (presumed false positive), 38/470 (8.1%) were antigenaemic, and 32/470 (6.8%) had evidence of past infection. The median S/CO ratios of the presumed false-positive and active infection samples were 1.8 and 17.3, respectively. The positive predictive value of HCV positivity in samples with ratios above 12 was 91.8%. On retesting, 104/470 (22.1%) samples became negative. The Architect anti-HCV assay has a very high false discovery rate in Ugandan BTSs, leading to excessive blood disposal. Pre-analytical factors likely contribute to this. An introduction of confirmatory testing using an algorithm based on S/CO ratio evaluation could limit unnecessary blood wastage and donor deferral.

Feasibility and effectiveness of HCV viraemia testing at harm reduction sites in Georgia: A prospective three-arm study.

Background and AimsIn 2015, Georgia began a hepatitis C virus (HCV) elimination programme. Although screening programmes have been decentralized for high‐risk groups, viraemic testing remains a bottleneck for people who inject drugs. Here, we describe two models of viraemic testing that aimed to address this gap.MethodsWe assigned eight harm reduction sites (HRS) to one of three arms (2,1:1): Xpert HCV viral load testing on‐site, blood draw on‐site with centralized HCV core antigen testing (HCVcAg), or standard‐of‐care (SOC) referral with viremia testing performed at treatment centres.Results1671 HCV‐seropositive participants were enrolled (Xpert, 37.1%; HCVcAg, 29.1%; referral, 33.8%). Participants were predominantly male (95.4%), mean age (IQR) 43 (37, 50) years and 1290 (77.2%) were currently injecting drugs. Significantly higher proportions of participants in the Xpert (100%) and HCVcAg (99.8%) arms received viraemia testing compared with the referral arm (91.3%) (Xpert vs referral, p < 0.0001; HCVcAg vs referral, p < 0.0001). Among viraemic participants, treatment uptake was similar (Xpert, 84.0%; HCVcAg, 79.5%; referral, 88.4%). The time between screening and sample collection for viraemia testing was significantly longer in the referral arm compared with both Xpert and HCVcAg arms (median 1 day compared with 0 days respectively), and the overall time between screening to treatment initiation was longer for the referral arm (median 67 days) compared with both Xpert and HCVcAg arms (median 57 and 50 days respectively).ConclusionsPoint‐of‐care viraemia testing and blood drawn on‐site for HCVcAg testing yielded more HCV‐seropositive patients receiving viraemic testing within a shorter timeframe compared with referrals.

Laboratory-based testing for hepatitis C infection using dried blood spot samples: A systematic review and meta-analysis of diagnostic accuracy.

The use of dried blood spot (DBS) samples can facilitate the implementation of reflex testing by circumventing the need for centrifugation and freezing of venous blood samples. This systematic review assessed the accuracy of using DBS samples to diagnose chronic hepatitis C virus (HCV) infection. A comprehensive search was undertaken to identify articles published up to July 2020 evaluating the diagnostic accuracy of anti-HCV, HCV-RNA and HCV core antigen tests using DBS. Screening, data extraction, quality appraisal and Grading of Recommendations, Assessment, Development and Evaluations certainty of the evidence assessment were performed independently by two reviewers. Meta-analysis, meta-regression and sensitivity analyses were conducted. The evidence demonstrates that laboratory-based anti-HCV and HCV-RNA tests using DBS samples have high diagnostic accuracy. All comparisons were between DBS and venous samples. For the detection of anti-HCV, sensitivity was 95% (95% CI: 92%-97%) and specificity was 99% ([95% CI: 98%-99%]; n=25; I2 =81%; moderate certainty). For the detection of HCV-RNA, the sensitivity was 95% (95% CI: 93%-97%) and specificity was 97% ([95% CI: 94%-98%]; n=20; I2 =52%; moderate certainty). The sensitivity of HCV core antigen tests was 86% (95% CI: 79%-91%) and specificity was 98% ([95% CI: 94%-99%]; n=5; I2 =37%; low certainty) compared with HCV-RNA (the gold standard for detecting chronic HCV). DBS samples could facilitate diagnosis of chronic HCV infection as the necessary sequential tests (anti-HCV and then HCV-RNA or HCV core antigen) can be undertaken using the same blood sample. This could reduce loss of patient follow-up and support international efforts towards HCV elimination in both high and low prevalence settings.

Role of hepatitis C virus core antigen assay in hepatitis C care in developing country

BackgroundThe World Health Organization (WHO) aims to achieve global hepatitis C elimination by 2030, defined as diagnosis of 90% of infected individuals and treating 80% of them. Current guidelines for the screening and diagnosis of hepatitis C infection denote using a relatively cheap screen with anti-hepatitis C virus (HCV) antibody immunoassay, followed by the much costlier molecular test for HCV RNA levels using polymerase chain reaction (PCR) assay to confirm active HCV infection. Simplification of the HCV evaluation algorithm to reduce the number of required tests could considerably expand the provision of HCV treatment especially in a developing country. This study investigates the performance of hepatitis C Core Antigen (HCV Ag) test by comparing HCV Ag results versus the results obtained with HCV ribonucleic acid (RNA) PCR which is considered the gold standard for the diagnosis of HCV infection.ResultsAmong the 109 anti-HCV positive sera, 96 were positive for both HCV Ag (> 3 fmol/L) and HCV RNA (> 15 IU/mL); 8 were negative for both tests, while the remaining 5 were positive for HCV RNA only. Considering the HCV RNA as gold standard; the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HCV Ag test were found to be 95.05%, 100%, 100%, and 61.54%, respectively. HCV genotype was performed for 59 patients. The most common HCV genotype was genotype 1 (72.9%). Genotype 2 (15.3%) and genotype 3 (11.9%) were detected in the others samples. A high level of correlation was seen between HCV RNA and HCV Ag (r = 0.958, p < 0.001). The correlation for the samples that were genotyped 1 was significant (r = 0.966, p < 0.001).ConclusionIn our study, it was found that there was strong correlation between HCV RNA levels and HCV Ag levels. So, it can be used for a one-step HCV antigen test to diagnose active HCV infection.

Hepatitis C core antigen test as an alternative for diagnosing HCV infection: mathematical model and cost-effectiveness analysis.

BackgroundThe cost and complexity of the polymerase chain reaction (PCR) test are barriers to diagnosis and treatment of hepatitis C virus (HCV) infection. We investigated the cost-effectiveness of testing strategies using antigen instead of PCR testing.MethodsWe developed a mathematical model for HCV to estimate the number of diagnoses and cases of liver disease. We compared the following testing strategies: antibody test followed by PCR in case of positive antibody (baseline strategy); antibody test followed by HCV-antigen test (antibody-antigen); antigen test alone; PCR test alone. We conducted cost-effectiveness analyses considering either the costs of HCV testing of infected and uninfected individuals alone (A1), HCV testing and liver-related complications (A2), or all costs including HCV treatment (A3). The model was parameterized for the country of Georgia. We conducted several sensitivity analyses.ResultsThe baseline scenario could detect 89% of infected individuals. Antibody-antigen detected 86% and antigen alone 88% of infected individuals. PCR testing alone detected 91% of the infected individuals: the remaining 9% either died or spontaneously recovered before testing. In analysis A1, the baseline strategy was not essentially more expensive than antibody-antigen. In analysis A2, strategies using PCR became cheaper than antigen-based strategies. In analysis A3, antibody-antigen was again the cheapest strategy, followed by the baseline strategy, and PCR testing alone.ConclusionsAntigen testing, either following a positive antibody test or alone, performed almost as well as the current practice of HCV testing. The cost-effectiveness of these strategies depends on the inclusion of treatment costs.

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

PurposeThe 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. MethodsIn 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. ResultsThe 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%. ConclusionThe 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

ObjectivesCommunity-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.DesignPopulation-based...

Improving Diagnosis of Hepatitis C Virus Infection Using Hepatitis C Core Antigen Testing in a Resource-Poor Setting.

INTRODUCTION: We compared the hepatitis C virus (HCV) core antigen test with the HCV RNA assay to confirm anti-HCV results to determine whether the HCV core antigen test could be used as an alternative confirmatory test to the HCV RNA test. METHODS:Sera from 156 patients were analyzed for anti-HCV and HCV core antigen using a chemiluminescent microparticle immunoassay (Architect i2000SR) and for HCV RNA using the artus HCV RG RT-PCR Kit (QIAGEN) in a Rotor-Gene Q instrument. RESULTS: The diagnostic sensitivity, specificity, and positive and negative predictive values of the HCV core antigen assay compared to the HCV RNA test were 77.35%, 100%, 100%, and 89.38%, respectively. HCV core antigen levels showed a good correlation with those from HCV RNA quantification (r =0.872). However, 13 samples with a viral load of less than 4000 IU/mL were negative in the HCV core antigen assay. All gray-zone reactive samples were also RNA positive and were positive on repeat testing.CONCLUSIONS: The Architect HCV core antigen assay is highly specific and has an excellent positive predictive value. At the present level of sensitivity (77%), the study is still relevant in a low-income setting in which most of the HCV-positive patients would go undiagnosed, since HCV RNA testing is not available and/or not affordable. HCV core antigen testing can also help determine the true burden of infection in a population, considering the fact that almost 50% of the anti-HCV positive cases are negative for HCV RNA.

Architect HCV Ag assay is an efficient alternative tool to RNA qRT-PCR quantification for assessing viral load in HCV infection

Objective To evaluate the performance characteristics of the automated Architect hepatitis C virus (HCV) core Ag assay versus HCV RNA by PCR among Egyptian patients and to assess its use for valuable clinical workup. Background HCV diagnosis by conventional anti-HCV assays has high rate of false positivity, false negativity, and a limited sensitivity for detection. Although HCV RNA assays are a reliable method for HCV diagnosis, they need technical skills and may also have false-positive results because of contamination. Moreover, the test is time consuming and more expensive. In contrast, the HCV core antigen test detects circulating HCV core antigen and identifies individuals who are actively infected with HCV. A commercialized test (the Architect HCV core antigen test) is supposed to have a sensitivity to detect ∼0.06 pg/ml and consequently a significant increase in sensitivity over the previous assay and a stronger correlation with HCV RNA testing. Patients and methods A descriptive, cross-sectional study was conducted on 60 HCV antibody-positive patients attending the outpatient clinic of Tropical Medicine Department, Al-Hussein University Hospital, Cairo, Egypt. The patients were classified into four groups based on the level of HCV viremia: group A included five patients with PCR below detection limit (12 IU/ml), group B included 39 patients with low viremia (&lt;100 000 IU/ml), group C included 13 patients with moderate viremia (100 000–10 000 000 IU/ml), and group D included three patients with high viremia (&gt;10 000 000 IU/ml). Each case was subjected to thorough clinical evaluation, HCV RNA quantification by Abbott Real Time HCV assay, and HCV Ag quantification by Architect HCV core antigen test. Results HCV Ag was found to be negative only in five of 55 HCV RNA-positive patients who had low level of viremia. The levels of HCV Ag showed a good correlation with those from the HCV RNA quantification (r=0.913, P≤0.001). Regarding HCV core antigen/HCV RNA ratio, it was not fixed for all patients. In most of them, each 1 pg/ml core Ag was equal to ∼10 000 IU/ml of RNA. Conclusion The Architect HCV Ag assay could be used as an alternative tool to HCV RNA PCR quantification in assessing viral load in HCV infection, and it has the advantages of lower cost, easy testing, and rapid reporting.

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

BackgroundHepatitis 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.MethodsWe 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.ResultsWe 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.ConclusionsAlthough 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.

Real-world utility of HCV core antigen as an alternative to HCV RNA testing: Implications for viral load and genotype.

Following positive serology, the gold standard confirmatory test of hepatitis C virus (HCV) infection is detection of HCV RNA by PCR. We assessed the utility of HCV core antigen testing to identify active infection among those positive for anti-HCV antibodies, when introduced to routine testing. We identified serum samples that were tested at a single laboratory in Scotland from June 2011to December 2017. Serum samples testing positive for HCV antibodies (HCV Ab positive) followed by reflex HCV core antigen (Ag) testing during the study period were identified. Those patients for whom a PCR test was requested on the baseline sample were also identified. For this group, the sensitivity and specificity of HCV Ag as a diagnostic tool were assessed using HCV PCR as gold standard. In our cohort of 744 patients, we demonstrated a sensitivity of 82.1% (95% CI 77.1%-86.2%) and a specificity of 99.8% (95% CI 98.6%-100%). Genotype 3 was associated with increased odds of a false-negative result (OR=3.59, 95% CI: 1.32-9.71), and reduced odds of a false negative were associated with older age (odds ratio (OR)=0.92, 95% CI: 0.88-0.97 per year) and viral load (OR=0.10, 95% CI: 0.05-0.21 per log10 IU/ml). While the implementation of HCV core antigen testing for diagnosis could lead to significant cost savings in national screening programmes, our data suggest that a significant proportion of HCV-infected individuals may be missed. These findings have implications for HCV diagnosis and determination of viral clearance after treatment, particularly in low- and middle-income regions, where genotype 3 is prevalent.