HCV Core Ag Research Articles

A-244 Performance Comparison of the Alinity i Hepatitis C Core Antigen Assay in Routine Laboratory Testing vs HCV RNA Testing

Abstract Background The elimination of Hepatitis C by 2030 is a goal established by the WHO and other country specific health organizations worldwide. This goal is enabled by the availability of effective treatment regimens. A recent surprise in the US has been the increase in HCV infections during the COVID 19 pandemic, which may be caused by increased needle sharing. HCV Antibody assays have been used to screen for HCV, but confirmation of acute infection is relegated in the current US guidelines to PCR which often takes multiple days and may result in a loss to follow up and treatment, especially in high prevalence populations. HCV Core Antigen is a new immunoassay on the Alinity i system. The aim of the study was to evaluate the precision, linearity, and sensitivity of this research use assay in a US-based population. Methods Alinity i assay HCV Ab is an automated chemiluminescent immunoassay built to measure total antibody to the virus. Similarly, the Alinity i HCV Core Ag is a research use only automated chemiluminescent immunoassay for detection of HCV Core antigen in human plasma and serum. Precision (repeatability, and reproducibility) was determined over 3 days (4–10 replicates/day) using control material consisting of a negative human plasma control, and positive controls made with recombinant core Ag in buffer. Linearity was evaluated by preparing 4 dilutions of a remnant specimen with detectable HCV RNA viral load. Clinical sensitivity was determined using 90 remnant specimens with positive HCV Ab results. Specimens were confirmed positive for Hepatitis C via HCV RNA quantitation using the Aptima HCV Quant Dx transcription-mediated amplification (TMA) assay on the Panther System. Correlation between the HCV Ag assay and TMA was evaluated using specimens submitted for either Hepatitis C infection screening and monitoring of known infection. Results The repeatability of the HCV Ag assay ranged between 3.7% and 11.1% CV depending on the sample S/CO level tested. Dilution recovery averaged 98.2% (range 90.2%–107.3%) and a plot of HCV Ag concentration vs dilution factor showed a correlation coefficient R = 0.998 The Hepatitis C core antigen assay had a correlation coefficient R = 0.92 with the TMA. The HCV assay demonstrated a clinical sensitivity of 96.7% vs TMA. Conclusion The performance characteristics of the Alinity i HCV Core Ag assay highlight an opportunity to speed time to treatment by reflexing on the same instrument from HCV Ab to Ag and confirming effectiveness of treatment.

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.

High agreement with HCV RNA in screening and DAA treatment monitoring indicates that cost-effective HCV core Ag test can also be enlisted in the fight to eliminate hepatitis C

High agreement with HCV RNA in screening and DAA treatment monitoring indicates that cost-effective HCV core Ag test can also be enlisted in the fight to eliminate hepatitis C

Approaches for simplified HCV diagnostic algorithms.

IntroductionIn the light of the advances in HCV antiviral therapy, global control of HCV infection becomes feasible but depends on the capacity of countries to identify infected people and to offer them treatment. To achieve the WHO goal which targets a diagnosis rate of 90% by 2030, simplification of screening and diagnosis will be crucial.MethodsPublished literature, unpublished data and expert consensus were used to determine key parameters, including point‐of‐care, rapid diagnostic testing, screening, the use of HCV core Ag and dried blood spots; starting from 2008 until November 2017. In addition, a manual search was undertaken to detect relevant papers or websites related to specific data from countries which underwent or are planning a programme of HCV elimination.ResultsSeveral strategies have been developed and evaluated these last years to simplify and facilitate access to screening and diagnosis, the development of reliable HCV core antigen tests and new nucleic acid amplification technologies for use in decentralized settings. In high prevalence settings, a one‐step screening and diagnosis strategy could simplify diagnostic algorithms provided the cost is reduced. Finally, genotyping may no longer be required in the context of availability of pangenotypic antiviral therapy.ConclusionsDespite relevant advances in HCV screening and diagnosis, the overall diagnosis package is still too expensive today and efforts must be made to allow generalized implementation of reliable tests in low and middle income countries. These efforts will be key factors to foster a real public health approach to HCV elimination.

Methylene Tetrahydrofolate Reductase Gene Polymorphism is Associated with Severity of Liver Steatosis in Chronically Infected Patients with HCV Genotype 4.

Methylene tetrahydrofolate reductase (MTHFR) C677T polymorphism was reported as a genetic variant in liver steatosis and fibrosis. This is a study of the association between MTHFR C677T polymorphism and HCV core with severity of steatosis in HCV GT4 patients. 111 HCV patients and 112 control subjects were recruited. Polymorphism was detected by RFLP analysis, core Ag was detected by ELISA. Combined HCV infection and MTHFR C677T polymorphism increases the risk to develop steatosis by 3.63- and 5.21-fold in subjects with single (CT) and double (TT) substitutions, respectively. Patients with chronic HCV infection had a 2.88- and 8.57-fold higher risk to develop steatosis in CT and TT genotypes, respectively, than patients with the (CC) genotype. No significant difference in core Ag titers were observed. MTHFR C677T polymorphism is a valuable genetic marker for steatosis, while HCV core Ag titer had no association with grades of steatosis in GT4 infections.

FRI-199 - Abbott HCV core Ag and HCV RNA comparison study in country of Georgia

FRI-199 - Abbott HCV core Ag and HCV RNA comparison study in country of Georgia

Hepatitis C virus core antigen assay: an alternative method for hepatitis C diagnosis.

Background The study aimed to evaluate a fully automated chemiluminescent immunoassay and compared it with a quantitative RNA assay and anti-HCV assay to verify the utility of this automated Ag assay as an alternative method for hepatitis C diagnosis. Methods A total of 229 serum samples previously tested for anti-HCV concentrations by the Architect Anti-HCV assay, were selected for HCV RNA testing by real time RT-PCR kit (Shanghai ZJ Bio-Tec Co., Ltd) and 125 specimens were tested for HCV Ag by the Architect HCV core Antigen kit. Results The log10 HCVAg and HCV RNA concentrations were highly correlated [ r = 0.834); with HCV RNA as the comparator test, HCVAg had 100% specificity, 100% positive predictive value (PPV) and 94.8% sensitivity. We found 1 pg/mL of total HCV core Ag is equivalent to approximately 6607HCV RNA international units (IU)/mL. Receiver operator characteristic curve analysis showed that the area under the curve of HCV core Ag (0.989) was greater than HCV Ab (0.871). HCV Ag concentrations and RNA-to-Ag ratio of the groups for HCV RNA concentrations ≤105 and >105 IU/mL were both significantly different from each other ( P < 0.05). Conclusion The Architect HCV core Ag assay may be an alternative method for hepatitis C diagnosis, performed on the same analytical platform and sample as the anti-HCV assay, shortening the diagnostic window period, demonstrating good correlation with HCV RNA assay with high specificity and positive predictive value.

Prevalence of Occult Hepatitis C Virus in Blood Donors in Zagazig City Blood Banks

Background: Egypt is reported as the country of highest incidence of HCV worldwide. The high rate of new cases reported require investigating uncommon sources of infection. Objectives: The study aimed to investigate the prevalence of occult hepatitis C infection (OCI) among blood donors from Zagazig city blood banks as a probable hidden source of transmission; and to evaluate HCV core Ag detection as a method for diagnosis of occult hepatitis C infection. Methodology: One hundred and forty blood donors from Zagazig university blood bank were incorporated into this study. Reverse transcription nested polymerase chain reaction from Peripheral Blood Monocyte (PBMC) and plasma obtained from subjects was done using HCV specific primers and HCV core antigen was detected using commercial ELISA kit. Results & Conclusion: HCV RNA was detected in PBMC extracted from 10 subjects (7.1 %). Two of them were also positive in plasma (1.4%). The overall incidence of OCI was 8/140 (5.7%). Out of them only one was also identified by ELISA HCV core antigen detection kit. The Comparison between ELISA technique for detection of HCV core antigen and nested PCR revealed sensitivity 30%, specificity 99.2% in PBMC and sensitivity 100%, specificity 98.6% in Plasma.

The Utility of Automated HCV Core Antigen Assay as an Alternative to PCR in Chronic HCV Egyptian Patients

Hepatitis C is a disease with a significant global impact. Although the detection and quantitation of HCV RNA have been the standard method for the diagnosis and assessing individual patient response to the antiviral drug regimen, it is very sensitive testing, expensive, labor intensive, and requires technical skill. Since the HCV core Ag assay is easy to perform in an immunoassay format, cheap, and less prone to sample carryover contamination compared to nucleic acid tests, There is an increasing interest to use HCV core antigen as a reflex test for seropositive individual to identify the active HCV infection also can be used to detect the early HCV infection. Aim of the work: To compare the diagnostic accuracy of HCV core antigen with HCV-PCR in chronic HCV Egyptian patients. Patients and methods: HCV core Ag was measured by a fully automated chemiluminescent immunoassay (CLIA) ABBOTT diagnostics in 57 patients proven to be chronic hepatitis C from those 32 were treated with pegylated interferon and ribavirin therpay and achieved HCV RNA negative six monthes after stoppage of treatment ( successful SVR) and 25 chronic HCV patients not considered for treatment . Viral load was quantified with branched DNA (bDNA, Versant, Siemens) also sera were tested with the Architect HCV Ag test (Abbott Laboratories). Statistical analysis was performed on logarithmically transformed values. Results: HCV core antigen was detectable in 19/25 and grey zone in 4/25 HCV RNA positive sera while 2 sera were negative for HCV Ag. HCV-Ag was undetectable in all 32 HCV RNA negative samples. The sample with the lowest viral load that tested positive for HCV-Ag contained 1200 IU/mL HCV RNA. The levels of HCV core antigen showed a good correlation with those from the HCV RNA quantification (r = 0.907) HCV core Ag levels were correlated significantly with ALT levels (r = 0.516; P < 0.0001) Conclusion: In conclusion, the Architect HCV antigen assay is highly sensitive, (>90%) reliable, easy to perform, cost-effective, and applicable as a screening, supplemental, and preconfirmatory test for anti-HCV assays used in laboratory procedures for the diagnosis of hepatitis C virus infection.

Usefulness of a fourth generation ELISA assay for the reliable identification of HCV infection in HIV-positive adults from Gabon (Central Africa).

Background/ObjectivesGuidelines for optimized HCV screening are urgently required in Africa, especially for patients infected with HIV, who sometimes show false positive or false negative reactivity in anti-HCV antibody assays. Here, we assessed the usefulness of a fourth-generation HCV Ag-Ab ELISA for the identification of active HCV infection in HIV-positive patients.MethodsThis cross-sectional study was conducted between 03/2010 and 01/2013 and included 762 Gabonese HIV-positive adult patients. The results of ELISA (Monolisa HCV Ag-Ab ULTRA, Bio-Rad) were compared with those obtained by RT-PCR (gold standard). The optimal ELISA signal-to-cutoff (S/CO) ratio to identify patients with active hepatitis C (positive HCV RNA) was determined. Specimens were further tested by the INNO-LIA HCV Score assay (Innogenetics) and the Architect HCV Ag kit (Abbott) to define the best diagnostic strategy.ResultsSixty-seven patients tested positive for HCV (S/CO ratio ≥ 1) by ELISA. Of these, 47 (70.1%) tested positive for HCV RNA. The optimal S/CO associated with active HCV infection was 1.7. At this threshold, the sensitivity of ELISA was 97.9% (95% confidence interval (CI) 90.0–99.9%), its specificity was 91.3% (95% CI 85.0–95.5%), and HCV seroprevalence rate was 7.3% (56/762) (95% CI 5.6–9.4%). Among 57 HCV-seropositive patients with available INNO-LIA results, false reactivity was identified in 14 (24.6%), resolved HCV infection in two (3.5%), possible acute HCV infections in nine (15.8%) and likely chronic HCV infections in 32 (56.1%) patients. HCV core Ag was undetectable in 14/15 (93.3%) specimens that tested negative for HCV RNA whereas it was quantified in 34 (out of 39, 87.2%) samples that tested positive for HCV RNA.ConclusionsOur study provides comprehensive guidance for HCV testing in Gabon, and will help greatly clinicians to improve case definitions for both the notification and surveillance of HCV in patients co-infected with HIV.

Analytical Evaluation of Hepatitis C Virus Core Antigen Detection as a Diagnostic Test in Diagnosis of HCV Infection

Purpose: The aim of the present study was to evaluate the efficacy of hepatitis C virus [HCV] core Ag assay by comparing it with anti-HCV antibodies and PCR-based technology for measuring viral load in diagnosis of HCV. Study design: HCV core Ag by ELISA in serum, in the presence or absence of antiHCV antibodies was compared to HCV- RNA by PCR on total number of 100 subjects, divided into 3 groups; including 80 patients and 20 volunteers. Results: The sensitivity of the test was (72.5%) and the specificity was (86.6%). Also positive predictive value of the test was (78.3%) and negative predictive value was (82.5%). Conclusion: Core antigen detection by ELISA can be used as a reliable test for detection of vireamia in HCV infection.

Early prediction of sustained virologic response by HCV Core Ag kinetics in chronic hepatitis C patients treated with Peginterferon plus Ribavirin

Early prediction of sustained virologic response by HCV Core Ag kinetics in chronic hepatitis C patients treated with Peginterferon plus Ribavirin

HCV Core Antigen Testing versus HCV PCR Testing for Early Detection of HCV Infection

HCV core antigen is detectable in serum several weeks earlier than anti-HCV antibodies. Variability in early detection time is even more pronounced in certain groups of patients such as the hemodialysis and immunocompromised where the antibody response may take between 45-68 days to develop. Early detection of HCV core Ag in serum may represent an attractive, cost effective screening tool for such high risk patients. The current study aimed at evaluation of the analytical performance of the Abbott Architect HCV Chemiluminescenat Microparticle Immunoassay (CMIA) in comparison to the standard PCR detection of HCV RNA. In addition, the current study evaluated the possible clinical utility of HCV Ag kit in testing pooled samples from several patients. Samples from 44 HCV patients and 15 controls were analyzed using the CMIA HCV core Ag assay and quantitative PCR. Samples from positive HCV patients were pooled and analyzed using the HCV core Ag assay. The current study demonstrated a sensitivity of 81.0% and specificity of 97.0% for the ABBOTT HCV core Ag kit assay in detecting HCV positive cases compared to quantitative PCR assay. The most important finding of the current study is that HCV core Ag assays may have false negative results at low level viremia (low HCV copy numbers). The current study does not support using HCV core Ag as a single test for screening possible HCV cases or using HCV core Ag assays on pooled samples. Bigger studies may be needed to strengthen the findings of the current study

Performance of HCV-Core Antigen Testing in Liver Transplanted Patients

Introduction: A new HCV core Antigen (HCVcoreAg) assay has recently been re-introduced as a diagnostic tool. We and others have shown a good performance in untreated immunocompetent patients (Mederacke et al, J Clin Virol. 2009 Nov;46(3):210-5). The aim of this study was to (i) evaluate the performance of the HCVcoreAg-assay in routine diagnostic settings in the context of immunosuppressed patients and (ii) to compare HCVcoreAg and HCV RNA kinetics early after liver transplantation. Methods: HCV core Ag was quantified by a fully automated immunoassay (Architect HCV Ag, Abbott, Germany). A concentration of HCVcoreAg of ≥3.00 fmol/L was considered reactive. HCV-RNA quantification was performed using the Cobas TaqMan assay with a lower limit of detection of 15 IU/ml (Roche Diagnostics, Germany). 601 samples from 415 patients were measured. 154 samples tested negative for both HCV-RNA and HCVcoreAg were excluded from the analysis. 66 patients underwent liver transplantation (LTX), 11 kidney transplantation (NTX) and 231 had no history of solid organ transplantation. In 12 patients HCV RNA and HCVcoreAg kinetics were measured early after liver transplantation (Day 0-8). Results: HCV-RNA and HCVcoreAg showed high correlations in LTX patients (r=0.71, p< 0.0001), in patients after NTX (r=0.97, p< 0.0001) and in patients with no history of transplantation (r=0.77, p< 0.0001). HCV RNA was tested positive in 37 samples being HCVcoreAg negative (median HCV RNA levels of those patients were 57 IU/mL). All patients positive for HCV-RNA were also tested positive for HCVcoreAg. After LTX kinetics of HCV-RNA and HCVcoreAg paralleled almost exactly in all patients. In 11 out of 12 patients HCV RNA and HCVcoreAg levels did not reach pretransplant levels one week after LTX. Conclusions: HCVcoreAg showed a very good performance in our study with very good correlations in all of our three patient groups. As the HCVcoreAg assay is cheaper compared to HCV RNA quantification, it might be used for frequent determinations of HCV-viremia which may have impact in LTX setting.

New approaches to in vitro diagnosis of hepatitis C infection a reason for post transfusion hepatitis: Diagnostic value of determination of hepatitis C virus core antigen

In between the dates of February 2008–March 2009, by applying to Istanbul University CTF Microbiology and Clinical Microbiology Basic Sciences Branch and Duzen laboratories, 123 cases, where HCV RNA and anti-HCV positivity are identified with molecular (real-time PCR) and serologic (ELISA) methods as a positive control group, and 48 cases where HCV RNA and anti-HCV negativity are identified as a negative control group are established. The values of sensitivity, specificity, positive and negative approximation of recently developed HCV Core Ag (Abbott Diagnostics, Germany) kit are determined successively as 94.3%, 97.9%, 99.1%, 87%, 95.3% and 88%. Although the new HCV Ag assay is clearly not sensitive enough to replace HCV NAT it may serve as a valuable tool in the HCV diagnostic algorithm as it is able to pick up a great majority of anti-HCV and HCV RNA positive samples, thus allowing a timely and less expensive serological diagnosis of an active HCV infection. This may be an advantage for labs that do not have access to PCR easily.

Post‐transplant recurrent hepatitis C: immunohistochemical detection of hepatitis C virus core antigen and possible pathogenic implications

The mechanisms by which severe cholestatic hepatitis develops after liver transplantation are not fully understood. Reports on immunohistochemical distribution of hepatitis C virus (HCV) antigens are still scarce, but recently, HCV immunostaining was suggested for early diagnosis of cholestatic forms of recurrent hepatitis C in liver grafts. After purification, Rb246 pab anticore (aa1-68) yielded specific, granular cytoplasmic staining in hepatocytes. Signal amplification through the Envision-Alkaline Phosphatase System avoided endogenous biotin and peroxidase. Rb246 was applied to liver samples of explants of 12 transplant recipients, six with the most severe form of post-transplantation recurrence, severe cholestatic hepatitis (group 1) and six with mild recurrence (group 2). We also assessed immuno-reactivity at two time-points post-transplantation (median 4 and 22 months) in both groups. HCV-core Ag was semiquantified from 0 to 3+ in each time point. Serum HCV-RNA was also measured on the different time points by branched DNA. In the early post-transplant time point, one patient had a mild staining (1+), two patients had a moderate staining (2+) and the other three had no staining in group 1, compared with five patients with no staining (0) and one patient with mild staining (1+) in group 2. Late post-transplant liver samples were available in nine patients, and two out of four samples in group 1 showed a mild staining, compared with no staining patients in five patients in group 2. Strikingly, on the explant samples, HCV immunostaining was strongly positive in group 1, and mildly positive in group 2. Two out of five samples showed 3+ staining, and three samples showed 2+ staining in group 1; two out of five samples showed no staining, two samples showed 1+ staining and one sample showed 2+ staining in group 2. Serum HCV-RNA was significantly higher in group 1, on both time-points post-transplantation. HCV-core Ag was not directly associated with serum HCV-RNA on the different time points. These preliminary results suggest that strong HCV immunostaining in the explant is predictive of more severe disease recurrence.

Hepatitis C virus Core Antigen as a predictor of non-response in genotype 1 chronic hepatitis C patients treated with peginterferon α-2b plus ribavirin

Background/Aims Chronic hepatitis C patients infected by genotype 1 are the least responsive to combination therapy and therefore monitoring response is important in identifying non-responders quickly, permitting therapy discontinuation and avoiding side effects and costs. We examined the usefulness of measuring total HCV Core Ag in early treatment with peginterferon α-2b and ribavirin in genotype 1 patients in the prediction of response and compared the results with those from HCV RNA quantification. Methods Two hundred and sixty-eight serum samples from 46 genotype 1 patients receiving combination therapy were examined for HCV Core Ag and quantitative HCV RNA. Results At baseline, mean HCV RNA and HCV Core Ag concentrations were significantly lower in sustained virologic responders than in non-responders. The negative predictive value of HCV Core Ag testing in predicting non-response at week 12 is 100%, and for a 2 log drop in HCV RNA, using two quantitative tests, it is 88%. Conclusions HCV Core Ag determination allows the identification of non-responders with only one test at week 12 and permits stopping therapy in these patients. HCV Core Antigen testing is cheaper and easier to perform than HCV RNA quantification.

466 HCV core Ag as a predictor of non-response in genotype 1 chronic hepatitis C patients treated with peginterferon alfa-2B plus ribavirin

466 HCV core Ag as a predictor of non-response in genotype 1 chronic hepatitis C patients treated with peginterferon alfa-2B plus ribavirin

Comparative Evaluation of the Total Hepatitis C Virus Core Antigen, Branched-DNA, and Amplicor Monitor Assays in Determining Viremia for Patients with Chronic Hepatitis C during Interferon Plus Ribavirin Combination Therapy

An assay prototype designed to detect and quantify total hepatitis C virus [HCV] core antigen (HCV core Ag) protein in serum and plasma in the presence or absence of anti-HCV antibodies has been recently developed by Ortho-Clinical Diagnostics. The aim of the study was to evaluate the sensitivity, specificity, and reproducibility of the Total HCV core Ag assay in comparison with two quantitative assays for HCV RNA: Quantiplex HCV RNA 2.0 (bDNA v2.0) or Versant HCV RNA 3.0 (bDNA v3.0) assays and the Cobas Amplicor HCV Monitor version 2.0 (HCM v2.0) test. We have studied samples of a well-characterized panel and samples from patients with chronic hepatitis C treated with interferon alone or with ribavirin. We have also compared the kinetics of HCV core Ag and HCV RNA in the follow-up of treated patients. The HCV core Ag assay exhibited linear behavior across samples from different genotypes. The coefficients of variation for intra- and interassay performance were 5.11 and 9.95%, respectively. The specificity of the assay tested in blood donors was 99.5%. Samples from HCV-infected patients showed that the correlation between the HCV core Ag and the two HCV RNA quantitative assays (bDNA and HCM v2.0) was 0.8 and 0.7, respectively. This correlation was maintained across different genotypes of HCV (r(2) = 0.64 to 0.94). Baseline HCV core Ag values were significantly lower in sustained responders to interferon (IFN) than in other groups of patients (5.31 log(10) [10(4) pg/ml] versus 5.99 log(10) [10(4) pg/ml]; P < 0.001). In patients treated with IFN or combination therapy, we found an association between a decrease of more than 2 log IU/ml in viral load, undetectable HCV core Ag, and sustained response. Among sustained responders to IFN alone or combination therapy and among relapsers after IFN alone, 84 out of 101 (83.2%) had undetectable HCV core Ag, and 76 out of 96 (79.2%) had a viral load decrease of >/=2 log IU/ml, after 1 month of treatment. In conclusion, the Total HCV core Ag assay is a new useful test for the detection of HCV viremia and the monitoring of patients treated with IFN alone or in combination with ribavirin.

Correlation between HCV core Ag and HCV-RNA levels using different commercial assay

Correlation between HCV core Ag and HCV-RNA levels using different commercial assay