Core Antigen Testing Research Articles

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

Hepatitis C virus (HCV) is a global public health care problem. Diagnosis of HCV infection was mainly based on the detection of anti-HCV antibodies as a screening test with serum samples and detection of HCV RNA by using RT-PCR, which considered as a golden standard test. In this study, we compared the HCV core antigen test with the HCV RNA assay for confirming anti-HCV results to determine whether the HCV core antigen test may be used as an alternative confirmatory test to the HCV RNA test and to assess the diagnostic values of the total HCV core antigen test by determining the diagnostic specificity and sensitivity rates compared with the HCV RNA test. Sera from 100 patients were analyzed for anti-HCV and HCV core antigen both with the ELISA and with the molecular HCV RNA assay consisting of a real time-PCR method as a confirmatory test. The diagnostic sensitivity, specificity, and positive and negative predictive values of the HCV core antigen assay compared to the HCV RNA test were 76.1%, 86.2%, 80%, and 82.5%, respectively. The HCV core antigen levels showed a poor correlation with those from the HCV RNA quantification (r = 0.321, p= 0.079). In conclusion, the core antigen detection test can be more valuable in HCV diagnosis than anti-HCV antibodies but it cannot replace HCV RNA in confirmation of the diagnosis of HCV because the sensitivity of the HCV core antigen detection assay is significantly lower than that of PCR-based methods.

The Role of Hepatitis C Virus Core Antigen Testing in the Era of Direct Acting Antiviral Therapies: What We Can Learn from the Protease Inhibitors.

Direct-acting antiviral (DAA) therapies have revolutionised the treatment of hepatitis C virus (HCV). The financial cost of DAAs however is significant, and first generation protease inhibitors (PIs) also require frequent monitoring of viral RNA levels to guide treatment. In this context, we examined the relevance of HCV antigen testing to evaluate the potential role in monitoring virological response to HCV antiviral treatment with the PI-based triple therapies, telaprevir (TVR) and boceprevir (BOC). Chronic HCV-infected individuals (n = 152) enrolled in the Irish Hepatitis C Outcomes Research Network (ICORN) study were prospectively analysed for baseline markers and the early viral kinetics associated with SVR. The sustained virological response (SVR) rates in the cohort receiving TVR and BOC were 87.3% and 73.8%, respectively. Baseline factors associated with successful outcome in TVR therapy were age (P = 0.0098), IFNL3 genotype (P = 0.0330) and viral load (P = 0.0456). RNA level at week 4 (P = 0.0068) and viral antigen negativity at week 2 (P = 0.0359) were predictive of SVR for TVR-based therapy. In BOC therapy, prior interferon treatment (P = 0.0209) and IFNL3 genotype (P = 0.0410) were baseline predictors of SVR. Evidence of viraemia based either on viral RNA or antigen at week 4 predicted SVR in these patients. Our data showed that rapid decline of HCV antigen to negative level at week 2 in TVR treatment and <0.96 log fmol/l in BOC treatment after commencement of PI triple therapy were associated with SVR. HCV antigen measurement should be considered as a potential alternative for monitoring treatment response during DAA-based regimens.

HEPATITIS C VIRUS (HCV) CORE ANTIGEN AS AN ALTERNATIVE TO PCR FOR HCV, RNA QUANTIFICATION TO EARLY DIAGNOSIS OF HCV INFECTION AMONG BLOOD DONORS

Background: Safety blood transfusion is based on reliable donor screening for transmissible infections such as the hepatitis C virus (HCV) infection. HCV-RNA by polymerase chain reaction (PCR) test is a gold standard test for HCV infection but with three major limitations: liability of RNA molecules, higher costs, and longer turnaround time as compared with HCV core antigen (HCVcAg) testing. Objective: To evaluate HCV core Ag as an alternative to PCR for HCV RNA to early diagnosis of HCV infection among blood donors. Patients and Methods: 4222 blood donors collected between March 2015 and July 2016 at Blood Bank Center of Najran Hospitals, Southwestern Saudia Arabia. Anti-HCV, HBsAg, syphilis and HIV were screened by third generation ELISA. Those reactive to HbsAg, syphilis and/or HIV were excluded. HCV core Ag and HCV RNA by RT-PCR were performed on 76 positive HCV-Ab sera. Results: Among total 4222 blood donors (3837 males (90.88%) and 385 females (9.12%)), 76 (1.8%) were positive for HCV-Ab (72 males; 94.74% and 4 females; 5.26%). HCV core Ag was ≥ 11 fmol/L in 65 cases (85.53%) of HCV Ab positive patients (61 males; 93.85% and 4 females; 6.15%), 3 cases with HCVcAg levels in grey zone (3-11 fmol/L) and 8 cases with HCVcAg ≤ 3 fmol/L all of both were males. HCV RNA was detected in 71/76 (93.42%) of donors with positive HCV-Ab and in 3 of 8 (37.5%) of those with positive HCV-ab and negative HCVcAg. HCVcAg has sensitivity, specificity, PPV and NPV of 97.14, 100, 100 and 99.76 values respectively at a cutoff 2.82 fmol/L compared to HCV RNA test. Conclusion: Higher sensitivity and specificity of HCVcAg with rapid turn around time of the results, and its lower price suggested that can be used alternatively to HCV RNA test in early diagnosis of HCV infection.

The end of the hepatitis C burden: Really?

The end of the hepatitis C burden: Really?

The Efficiency of Hepatitis C Virus Core Antigen Test in the Diagnosis of Hepatitis C Infection

OZ Objective: It was aimed to investigate diagnostic value of hepatitis C virus (HCV) core antigen test in patients with positive or negative anti-HCV assay by comparing with HCV ribonucleic acid (RNA) assay. Materials and Methods: Serum samples obtained from 189 patients who were admitted to Necmettin Erbakan University Meram Faculty of Medicine between December 2010 and February 2012, and HCV RNA assay were carried out for various reasons. Two mL of samples were stored under suitable conditions and antiHCV, HCV core antigen and strip immunoblot assay [Commercial INNO LIA™ HCV Score (Innogenetics NV in Ghent, Belgium)] were performed. Genotyping was performed in the amplicons of the samples with positive HCV RNA test. Results: The diagnostic sensitivity specificity, negative predictive value and positive predictive value of HCV core antigen test were 96.2%, 100%, 97.3%, and 100%, respectively. Sixty-five serum samples were genotyped and their distribution were detected: Fiftynine samples were genotype 1b, 2-genotype 1a/1b, 1-genotype 3a, 1-genotype 4, 1-genotype 2a/2c, and 1 was genotype 1a. Conclusion: It was concluded that HCV core antigen assay is highly specific, sensitive, reliable, reproducible, and easy to perform. It may be applied as a supplemental and confirmatory test in anti-HCV assays in the diagnosis of HCV.

Course of hepatitis C virus (HCV) RNA and HCV core antigen testing are predictors for reaching sustained virologic response in liver transplant recipients undergoing sofosbuvir treatment in a real-life setting.

Hepatitis C virus (HCV) infection is associated with reduced graft survival in orthotopic liver transplant recipients. Treatment with the new direct-acting antivirals (DAAs) is safe and efficient, but no reliable predictive factors for sustained virologic response (SVR) have been identified so far. The HCV core antigen assay (HCV-core-Ag) is a new, inexpensive, and efficient method to detect viral antigens, but the value of this technique to predict treatment response in orthotopic liver transplantation (OLT) patients is still unclear. All OLT patients who were treated with a sofosbuvir-based antiviral regimen at our center between March 2014 and August 2014 were included in the analysis (n = 20). HCV-core-Ag and HCV RNA (polymerase chain reaction [PCR]) were determined at each visit. Primary endpoints of this study were SVR at 4 or 12 weeks after end of treatment (SVR 4 and SVR 12). HCV-core-Ag tested negative after a median of 2 weeks (range 1-16 weeks) while PCR tests became negative after a median of 4 weeks (range 2-12 weeks). Time until PCR negativity and until HCV-core-Ag negativity showed a good correlation (R = 0.711, P < 0.001, Fig. ). Seventeen of 20 patients (85%) achieved SVR 12. SVR 12 was associated with a short time interval between treatment start and HCV PCR negativity (P = 0.005) or HCV-core-Ag negativity (P = 0.003, Mann-Whitney test). No severe side effects were observed. DAA treatment is safe and well tolerated in OLT. The time points of HCV-core-Ag loss and PCR negativity were predictors of SVR 12.

P0748 : Course of HCV RNA and HCV core antigen testing are predictors for reaching SVR in transplant recipients

P0748 : Course of HCV RNA and HCV core antigen testing are predictors for reaching SVR in transplant recipients

Hepatitis B and C virus infections among patients with end stage renal disease in a low-resourced hemodialysis center in Vietnam: a cross-sectional study.

BackgroundHemodialysis services in Vietnam are being decentralised outside of tertiary hospitals. To identify the challenges to infection control standards for the prevention of bloodborne infections including hepatitis B virus (HBV) and hepatitis C virus (HCV) we tested the magnitude of HBV and HCV infections in the largest unit in Ho Chi Minh City servicing patients with end stage renal disease.MethodsAll 113 patients provided consent HBV surface antigen (HBsAg) and HCV core antigen (HCV-coreAg) testing. Positive patients were tested for viral genotypes. All participants completed a questionnaire on demographic characteristics, risk factors and previous attendance to other hemodialysis units.ResultsSeroprevalence of 113 patients enrolled was 7% (8/113, 95% CI 2.3%-11.8%) HBsAg, 6% (7/113, 95% CI 1.7%-10.6%) HCV-coreAg and 1% (1/113, 95% CI 0.8%-2.6%) co-infection. Having a HBV positive sexual partner significantly increased the risk of acquiring HBV (P = 0.016, Odds Ratio (OR) =29, 95% CI 2–365). Risk factors for HCV included blood transfusion (P = 0.049), multiple visits to different hemodialysis units (P = 0.048, OR = 5.7, 95% CI 1.2–27.5), frequency of hemodialysis (P = 0.029) and AST plasma levels >40 IU/L (P = 0.020, OR = 19.8, 95% CI 2.3–171). On multivariate analysis only blood transfusion remained significant risk factor for HCV (P = 0.027, adjusted OR = 1.2).ConclusionsHCV screening for HCV of blood products must improve to meet the infection prevention challenges of decentralizing hemodialysis services. The level of HCV and HBV in our hemodialysis unit is a warning that universal precautions will be the next challenge for decentralised hemodialysis services in Vietnam.

Performance of ARCHITECT HCV core antigen test with specimens from US plasma donors and injecting drug users

BackgroundHepatitis C virus (HCV) core antigen is a serological marker of current HCV infection. ObjectivesThe aim of this study was mainly to evaluate the performance characteristics of the ARCITECT HCV core antigen assay with specimens from US plasma donors and injecting drug users. Study designA total of 551 serum and plasma samples with known anti-HCV and HCV RNA status were tested for HCV core antigen using the Abbott ARCHITECT HCV core antigen test. ResultsHCV core antigen was detectable in 100% of US plasma donor samples collected during the pre-seroconversion phase of infection (anti-HCV negative/HCV RNA positive). Overall sensitivity of the HCV core antigen assay was 88.9–94.3% in samples collected after seroconversion. The correlation between HCV core antigen and HCV RNA titers was 0.959. ConclusionsHCV core antigen testing may be reliably used to identify current HCV infection.

Comparison of two diagnostic algorithms for the identification of patients with HCV viremia using a new HCV Antigen test

Background. Patients exposed to hepatitis C virus (HCV) may develop chronic infection with viremia. The diagnosis of this condition requires the use of several laboratory tests in algorithms tailored to the population and resources available for each laboratory.Aim. We compared the diagnostic efficacy of two diagnostic algorithms for the identification of viremic patients with HCV. One based on confirmation of reactive antibody results with molecular techniques (reverse transcription polymerase chain reaction, RT-PCR) and the other based on the use of a new HCV core antigen test (HCV Ag).Material and methods. We measured levels of anti-HCV, HCV Ag and viral load (trough RT-PCR) in parallel, in 211 samples (53 antibody positive, 158 antibody negative). Using the three results available for each sample we simulated the diagnostic performance of the two algorithms and compared them to the results of RT-PCR as gold standard.Results. Both algorithms showed a high degree of concordance for viremic patients. The percentage of correctly classified patients was 99.05% for the algorithm based on RT-PCR and 98.10% for the HCV Ag algorithm. The HCV core Ag test showed a clinical sensitivity of 0.917 and showed a good correlation to the results of molecular biology. Spearman rank correlation coefficient (ρ) of 0.97 (95% CI 0.95 to 0.99, p < 0.0001). Conclusion. An algorithm incorporating HCV Ag as confirmatory test for anti-HCV results is a feasible alternative to the use of molecular techniques in laboratories that do not have access to them or require faster turn around times.

Hepatitis C virus core antigen testing: role in diagnosis, disease monitoring and treatment.

While hepatitis B virus (HBV) screening relies on hepatitis B surface antigen to confirm HBV infection since the early days of hepatitis B disease management, hepatitis C virus (HCV) infection screening is based on anti-HCV testing which does not discriminate active from past infection. Thus to confirm infection HCV RNA testing has been required; recently a HCV core antigen assay became widely commercially available which could serve to confirm infection. That assay is less sensitive than current HCV RNA assays, but as more than 50% of anti-HCV positive persons will be HCV core antigen positive, HCV core antigen testing can be a cost effective and reflex test to confirm HCV infection in anti-HCV positive individuals and will be easier as it can be applied on the same platform. For treatment monitoring, more data need to be generated, but the early data available at present suggest that HCV core antigen may be an alternative to HCV RNA monitoring. With direct antivirals, HCV core antigen could even be superior to HCV RNA testing, as direct antivirals might already prevent virus formation when HCV core antigen is still produced and thereby correlates better with eventual viral clearance.

Can HCV core ag testing replace the routine screening assays in patients on hemodialysis?

Dear Editor We have recently read with great interest the article published in your most valuable journal entitled “Hepatitis C virus infection rate among seronegative hemodialysis patients screened by two methods: HCV core antigen and polymerase chain reaction” by Moini et al. (1). This study focused its message on determination of the prevalence of hepatitis C virus (HCV) infection in seronegative hemodialysis (HD) patients using two methods of HCV core antigen (Ag) testing by ELISA assay, and the real time polymerase chain reaction. The authors have concluded that HCV core Ag testing could be used as a sensitive method for HCV infection screening in patients on HD (1). We agree that patients on long-term HD are at higher risk of acquiring HCV infection (2, 3). Despite administration of recombinant erythropoietin, HCV transmission is still being reported among patients on HD (4, 5). Undoubtedly, HCV screening is crucial for patients on HD since these population is at increased risk of infection and moreover it easily spreads the infection through dialysis units (6). HCV infection is routinely diagnosed by measuring anti-HCV antibody whereas the antibody is undetectable in the first four to six weeks of infection, the so-called, window period (7). Furthermore, there is a blunted antibody response in patients on HD due to depressed immune system (1). Kidney Disease Improving Global Outcomes (KDIGO) has recommended the use of nucleic acid amplification technology (NAT) in detection and evaluation of HCV in chronic kidney disease (8). By utilizing NAT, some problems emerge: the kits are frequently unavailable; considerable skill is required; there is limited reproducibility; and most importantly, the costs are steep (7). Some studies in the general population have pointed out the importance of HCV core Ag detection as an alternative to NAT for early diagnosis of infection as well as predicting and monitoring the response to therapy (9); however few studies concerning its efficacy in patients on long-term HD exist (7, 10). We totally concur with the authors that HCV core Ag may be an accurate marker for early detection and virological monitoring of HCV infection in patients on HD. Owing to the low cost and its technical easiness, this assay can be employed for routine screening of patients on HD; however, more studies with larger sample size are still required to effectively establish HCV core Ag test as a preferred assay for the early diagnosis of HCV infection in patients on HD.

HCV Antigen Testing for the Diagnosis of Hepatitis C Infection: A Cost-Efficient Algorithm

In North America, diagnosis of active hepatitis C virus (HCV) infection is currently performed using RNA testing which is highly sensitive and specific but is associated with three major limitations: lability of RNA molecules, higher costs, and longer turn-around time as compared with commercially-available HCV core antigen testing. In the current study, a new HCV core antigen assay product was evaluated for the diagnosis of HCV infection and its cost reducing potential. Ninety plasma specimens positive for HCV RNA along with 25 negative HCV specimens were used for HCV antigen assay. Twenty-four specimens positive for a panel of agents were used for possible cross-reactivity. Sixty-four HCV antibody-positive specimens with negative HCV RNA and indeterminate HCV immunoblot results were also employed. In the first group, 78/90 (86.6%) tested positive for HCV antigen with regression analysis showing no significant deviation from linearity. None of the prenatal specimens tested positive for HCV antigen. Non-specific reactions were not observed. In the HCV antibody-indeterminate group, only 2/64 (3.1%) were antigen positive. In the last group, none of the HCV antibody very-low-positive specimens tested positive for HCV antigen. Both inter- and intra-run reproducibility of 100% were noted. The cost analysis showed a minimum of 52.13% reduction in costs associated with qualitative RNA testing. Considering the complexity of HCV infection diagnosis and the significant cost and turn-around time burden it imposes on clinical laboratories, HCV antigen testing seems an attractive adjunct to the current battery of laboratory diagnosis that demands more attention.

Hepatitis C virus core antigen testing in liver and kidney transplant recipients

HCV RNA levels correlate with the long-term outcome of hepatitis C in liver transplant recipients. Nucleic acid testing (NAT) is usually used to confirm HCV reinfection and to examine viral loads after liver transplantation. HCV core antigen (HCVcoreAg) testing could be an alternative to NAT with some potential advantages including very low intra- and interassay variabilities and lower costs. The performance of HCVcoreAg testing in organ transplant recipients is unknown. We prospectively studied 1011 sera for HCV RNA and HCVcoreAg in a routine real-world setting including 222 samples obtained from patients after liver or kidney transplantation. HCV RNA and HCVcoreAg test results showed a consistency of 98% with a very good correlation in transplanted patients (r > 0.85). The correlation between HCV RNA and HCVcoreAg was higher in sera with high viral loads and in samples from patients with low biochemical disease. Patients treated with tacrolimus showed a better correlation between both parameters than individuals receiving cyclosporine A. HCV RNA/HCVcoreAg ratios did not differ between transplanted and nontransplanted patients, and HCV RNA and HCVcoreAg kinetics were almost identical during the first days after liver transplantation. HCVcoreAg testing can be used to monitor HCV viral loads in patients after organ transplantation. However, the assay is not recommended to monitor antiviral therapies.

English

Quantitative tests for the detection of hepatitis C virus ribonucleic acid (HCV-RNA) levels and HCV core antigen have been mainly used for the management of patients with HCV infection. The aim of this study was to evaluate the correlation between HCV core antigen and HCV RNA levels in patients reactive for anti-HCV antibodies. Three hundred and twenty-five anti-HCV reactive sera samples were included in the study. HCV core antigen and HCV RNA levels were determined using the Architect HCV Ag test and Abbott RealTimeTM HCV RNA test (RT-PCR), respectively. The correlation coefficient between the levels of HCV core antigen and HCV RNA test results was calculated using Spearman&rsquo;s rank test, and linear regression analysis was applied. One hundred and sixteen of the 325 samples were detected positive by both methods. Three additional samples by RT-PCR, and 4 samples by Architect HCV Ag, the negative samples were found positive by the other method. All of these contradictory results were obtained from the low level HCV RNA or HCV core antigen including samples. A correlation coefficient (r) was determined as 0.899 between the levels of HCV core antigen and HCV RNA (p&lt;0.0001). The sensitivity, specificity, positive predictive value and negative predictive value of the HCV core antigen test were 97.48, 98.06, 96.67 and 98.54%, respectively, using the HCV RNA test as a reference. The Architect HCV core antigen test exhibits a good correlation with the HCV RNA test. It can be used as an alternative method, especially when the HCV RNA test is unavailable. &nbsp; Key words: Anti- hepatitis C virus, Architect hepatitis C virus Ag test, hepatitis C virus RNA.

Patients Screened by Two Methods; HCV Core Antigen and Polymerase Chain Reaction

BackgroundEnd-stage renal disease patients on chronic hemodialysis are among high risk groups for hepatitis C virus (HCV) infection for whom routine HCV screening is recommended. Anti-HCV antibody (ab) testing may not be reliable to detect all infected cases because of the blunted ab response due to depressed immune state in these patients. Using a more reliable, cost-effective and non-complex HCV screening test may be necessary in this group of patients for case finding and management, and also for prevention of infection spread.ObjectivesThe aim of this study was to find the prevalence of HCV infection in HCV ab negative hemodialysis patients by Real time PCR and total HCV core antigen (ag) test and comparing the results of the two tests.Patients and MethodsFrom a single hemodialysis center, 181 anti- HCV ab negative patients were screened by total HCV core ag using an ELISA kit. Real time PCR was used for determination of the virus and viral load quantity.ResultsAmong the 181 anti-HCV ab negative patients, 13 (7.2%) were positive for HCV core ag and 11 (6%) had detectable HCV RNA with a range of 40-336543 IU/ml by PCR. The two tests had a high measurement agreement (Kappa=0.82, P<0.001). Of the 13 patients with positive HCV core ag test results, 3 were negative for HCV RNA. Considering real time PCR for HCV RNA as the gold standard for HCV infection determination in this patient population, HCV core ag assay yielded a sensitivity of 90.9%, specificity of 98.2%, positive predictive value of 76.9% and negative predictive value of 99.4%.DiscussionThe rate of HCV infection among HCV ab negative hemodialysis patients was high. HCV core ag testing could be used as a sensitive method for HCV infection screening in this group of patients.

Molecular virology in transfusion medicine laboratory.

and antibody to HBV core antigen (anti-HBc) testing began in the 80s to reduce transmission of non-A, non-B viral hepatitis. Then, the advent of the human immunodeficiency virus (HIV) epidemic and the rapidly following identification of hepatitis C virus (HCV) triggered unprecedented efforts to avoid the transmission of these new blood-borne viruses, and the implementation of antibody assays for both of these agents. To exclude individuals at risk for transmissible viral infection, donor screening process has been developed and implemented that includes the medical history of the candidate donor, a brief physical examination, and serologic testing. The next critical step in reducing viral TTI was achieved with the implementation of NAT technology 2 . Rapid progress and constant improvements in nucleic acid amplification technologies resulted in an unprecedented technological turning point in the molecular diagnostic and characterisation of viral infections. NAT combines the advantages of direct and highly sequence-specific detection of viral genomes (DNA or RNA) with an analytic sensitivity that is several orders of magnitude greater than that of antigen detection or virus isolation methods. Adequate specificity and high sensitivity combined with high throughput and the increasing availability of commercial assays, made NAT particularly suitable to screen blood donations for the presence of viral genomes. However, the considerable cost of NAT and challenges in automation led the users to develop strategies based on pooling of multiple donor samples

Hepatitis C virus core antigen test in monitoring of dialysis patients.

Hepatitis C virus infection is a persistent worldwide public health concern. The prevalence of HCV infection is much higher in patients on chronic haemodialysis (HD) than in the general population. HCV infection can detrimentally affect patients throughout the spectrum of chronic kidney disease. Despite the control of blood products, hepatitis C virus transmission is still being observed among patients undergoing dialysis. Detection systems for serum HCV antibodies are insensitive in the acute phase because of the long serological window. Direct detection of HCV depends on PCR test but this test is not suitable for routine screening. Recent studies have highlighted the importance of HCV core antigen detection as an alternative to PCR. Few studies exist about the efficacy of HCV core antigen test in dialysis population. We studied the utility of HCV core antigen test in routine monitoring of virological status of dialysis patients. We screened 92 patients on long-term dialysis both by PCR HCV-RNA and HCV core antigen test. The sensitivity of HCVcAg test was 90%, the specificity 100%, the positive predictive power 100%, the negative predictive power 97%, and the accuracy 97%. We think serological detection of HCV core antigen may be an alternative to NAT techniques for routine monitoring of patients on chronic dialysis.

Core antigen tests for hepatitis C virus: a meta-analysis

Diagnosis and monitoring of hepatitis C virus (HCV) infection relies mainly on the detection of HCV antibodies and HCV RNA. HCV antibody test has a longer window period and is not applicable in the immunosuppressed population. Although HCV RNA test reduces the window period, it is still not widely recommended because of its high cost and requirement of specific equipment. HCV core antigen is another direct virological marker which has been investigated in recent years. HCV core antigen assay is as simple as the HCV antibodies assay and can detect HCV infection only 1 day delay compared to the HCV RNA assay. In order to evaluate the application of HCV core antigen test in HCV diagnosis and management, we performed this meta-analysis. Twenty five articles were finally included in meta-analysis. All statistical analyses were performed with MetaDisc 1.4 and Stata 11.0. The pooled sensitivity of HCV core antigen assay was 0.84 (95 % CI, 0.83-0.85), and the pooled specificity was 0.98 (95 % CI, 0.97-0.98). HCV core antigen assays may not displace HCV RNA assays to be a definitive diagnosis of HCV infection until now. Considering the higher sensitivity (0.926) and specificity (0.991) of subgroup, HCV-cAg detection is a promising method as a confirmatory test for HCV antibody positive, therapy-naive individuals. Explored by meta-regression and subgroup analysis, possible sources of heterogeneity of specificity was found, while the heterogeneity of sensitivity was still significant.

The potential role of HCV core antigen testing in diagnosing HCV infection

The potential uses of serological tests that detect HCV core antigens in biological fluids are highlighted. The most common serological tests utilized to detect exposure to HCV rely on the detection of antibodies to HCV. However, these tests cannot distinguish between individuals who have resolved their infection and those who remain actively infected with HCV. By contrast, the HCV core antigen test detects circulating HCV core antigen and identifies individuals who are actively infected with HCV. There is increasing interest in using the HCV core antigen test as a reflex test for seropositive individuals to identify individuals who are actively infected with HCV. In addition, the HCV core antigen test can be utilized to detect the early phase of HCV infection prior to the development of antibodies, both in the blood bank setting and in the diagnostic laboratory. Lastly, quantitative versions of the HCV core antigen test can be used to monitor the effectiveness of antiviral therapy.