Evaluation of a total hepatitis C virus (HCV) core antigen assay for the detection of antigenaemia in anti-HCV positive individuals (original) (raw)
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Enfermedades infecciosas y microbiologia clinica, 2017
Detection of hepatitis C virus (HCV) RNA and the HCV core antigen assay (HCV-Ag) are reliable techniques for the diagnosis of active and chronic HCV infection. Our aim was to evaluate the HCV-Ag assay as an alternative to quantification of HVC RNA. A comparison was made of the sensitivity and specificity of an HCV-Ag assay (204 serum samples) with those of a PCR assay, and the correlation between the two techniques was determined. The sensitivity and specificity of HCV-Ag was 76.6% and 100%, respectively. Both assays were extremely well correlated (Pearson coefficient=0.951). The formula (LogCV=1.15*LogAg+2.26) was obtained to calculate the viral load by PCR from HCV-Ag values. HCV-Ag was unable to detect viral loads below 5000IU/mL. Although the HCV-Ag assay was less sensitive than the PCR assay, the correlation between both assays was excellent. HCV-Ag can be useful as a first step in the diagnosis of acute or chronic HCV infection and in emergency situations.
in Vivo, 2023
Background/Aim: 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. Materials and Methods: 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]. Results: 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). Conclusion: 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.
Journal of Clinical Microbiology, 2004
The British Columbia Center for Disease Control laboratory performs approximately 95% of all hepatitis C virus (HCV) antibody tests for the province's 4 million inhabitants. In 2002, the laboratory tested 96,000 specimens for anti-HCV antibodies, of which 4,800 (5%) were seroreactive and required confirmation of active infection. Although HCV RNA assays with a sensitivity of 50 IU/ml or less are recommended for the confirmation of active HCV infection, given the large number of seroreactive specimens tested annually, we evaluated the Ortho trak-C assay (OTCA) as a second-line confirmatory test and determined its limit of detection (LoD). Of 502 specimens from treatment-naïve anti-HCV-positive individuals, 478 had sufficient volumes for evaluation by the OTCA and HCV RNA tests. Core antigen was not detected in 147 of 478 (30.8%) of these specimens, of which 37 of 147 (25.2%) were shown to be viremic by the VERSANT HCV (version 3.0) (branched-DNA) assay and/or the VERSANT HCV qualitative assay. Testing of 144 replicates of a World Health Organization standard dilution series indicated that the LoD of OTCA was ϳ27,000 IU/ml. This LoD is consistent with the inability of OTCA to detect core antigen in clinical specimens with low viral loads. We conclude that OTCA has limited value as a confirmatory test for the diagnosis of active HCV infection because 37 of 367 (10%) of viremic specimens had undetectable core antigen. Qualitative HCV RNA testing remains the present standard for the confirmation of active HCV infection in the diagnostic setting.
African Journal of Microbiology Research, 2012
A total of 152 serum samples of which 112 anti-HCV-Ab positive (range 1.08 to 386.54 s/co) and 40 anti-HCV-Ab negative (<1 s/co) were analyzed with HCV-RNA and HCV-Ag tests. According to HCV-RNA detection, sensitivity and specificity of HCV-Ag test was measured as 96.9 and 100%, respectively and of anti-HCV-Ab were measured as 100 and 60%, orderly. An excellent positive predictive value for HCV-Ag test was detected as 100%, whereas 28.5% for anti-HCV-Ab test. Pearson correlation analysis showed that there was a statistically significant and strong relationship (p < 0.001, R: 0.773) between HCV-Ag and HCV-RNA quantification analysis. The correlation between the two tests showed an exponential trend (R 2 : 0.949). These results suggest that HCV-Ag test may be a reliable assay for HCV antigen detection, which is also well-correlated with serum viral load. However, large studies, including different HCV genotypes and with extreme viral quantity, are required to assess analytic potency of this novel kit.
Clinical Infectious Diseases, 2002
Quantification of hepatitis C virus (HCV) RNA is important in the assessment of HCV-associated liver disease in patients coinfected with HCV and human immunodeficiency virus (HIV). To investigate whether the standard integrity of competing test methodologies might be compromised by higher HCV titers in coinfected patients, 2 technologies (a polymerase chain reaction-based assay [COBAS Amplicor 2.0 assay; Roche Diagnostics] and a branched-chain DNA assay [Versant 3.0; Bayer]) were evaluated by testing paired serum samples from 68 coinfected patients and 137 HCV-monoinfected patients. Although the correlation was highly significant (;), HCV RNA titers expressed in international units per milliliter could not be standardized; r p 0.81 P ! .001 statistically significant differences were observed in all quartiles. Significant variability () was observed P ! .0007 in the classification of patients as having a high versus a low virus titer (cutoff, 800,000 IU/mL), which suggests that standardization in international units has low efficacy among coinfected patients. Clinicians should note that test variability precludes direct comparability of HCV RNA titers, particularly in coinfected patients with high titers. Hepatitis C virus (HCV) infection has emerged as a major contributor to liver injury and hepatic decompensation in patients with HIV infection. HCV may be detected indirectly by serological methods (e.g., EIA or recombinant immunoblot assay) or by direct testing for the presence of HCV RNA. Although EIA is recommended as a first-line method for the screening of potentially infected patients, false-positive reactions have
Journal of Clinical Microbiology, 2002
Reference Testing Laboratory HCV RNA transcription-mediated amplification assay (HCV TMA) were compared for analytical sensitivity, clinical performance, and workflow. Limits of detection were determined by testing dilutions of the World Health Organization HCV standard in replicates of 15 at concentrations of from 1.0 to 70 IU/ml. The limit of detection of the HCV PCR assay was calculated to be 45 IU/ml on initial testing and 32 IU/ml after resolution of gray zone results. The calculated limit of detection for HCV TMA was 6 IU/ml. To compare clinical performance, 300 specimens, grouped as follows, were evaluated: 112 samples that were indeterminate in an anti-HCV enzyme immunoassay (EIA) and for which HCV RNA was not detected by HCV PCR; 79 samples that were EIA positive and for which HCV RNA was not detected by HCV PCR; and 105 samples that were both EIA and HCV PCR positive. For these groups, interassay concordance ranged from 96.2% to 100%. In addition, three HCV PCR gray zone specimens and one neonatal specimen were also evaluated. A 64-sample run (full run, 91 specimens) required 5 h for testing by HCV TMA, whereas almost 8 h were required to test a full run of 22 specimens by HCV PCR. HCV TMA demonstrated excellent concordance with HCV PCR when clinical samples were tested. However, HCV TMA was more sensitive than HCV PCR, required less time for test result completion, and had a greater throughput.
Diagnostic Microbiology and Infectious Disease, 2011
In this study, the utility and impact of hepatitis C virus (HCV) core antigen (Cag) detection via a commercial assay have been evaluated in diagnostic laboratory conditions. In a total of 272 samples from 226 individuals, HCV RNA was detected in 81.3% and anti-HCV antibody prevalence was 86.4%. HCV Cag reactivity was identified in 59.9% of the samples and in 75.8% with detectable RNA. The sensitivity and specificity of HCV Cag assay have been calculated as 75.8% and 95.1%, respectively, and agreement between HCV RNA and HCV Cag was moderate (κ = 0.554). HCV Cag and RNA levels were highly correlated (r = 0.915 and 0.937). A viral load threshold of 10 3 IU/mL has been recognized, above which the correlation with RNA became statistically significant and sensitivity increased to 90.9%. Detection and quantification of HCV core antigen have been observed as a strong alternative to nucleic acid testing for HCV monitorization.
Journal of Clinical Virology, 2011
Background: Testing for hepatitis C virus core antigen (HCV Ag) may represent a complementary tool to anti-HCV and HCV-RNA in the diagnosis and monitoring of HCV infection. Objective: To evaluate the performance characteristics of the automated Abbott ARCHITECT HCV Ag assay. Study design: Five sites analyzed over 3000 routine serum samples from populations at different risk, comparing HCV Ag results with anti-HCV screening and supplemental assay results and with HCV-RNA. Results: The HCV Ag assay showed a specificity of 100%, a good precision (CV < 10%) and excellent dilution linearity (r > 0.999). The sensitivity (3 fmol/L) corresponds to 700-1100 IU/mL of HCV-RNA. A non-linear correlation with HCV-RNA was found: r = 0.713 vs. Siemens bDNA (523 specimens), r = 0.736 vs. Roche Cobas TaqMan (356 specimens) and r = 0.870 vs. Abbott Real-Time PCR (273 specimens). HCV Ag quantitation was equally effective on different HCV genoypes (239 for genotype 1/1a/1b/1c, 108 for genotype 2/2a/2c, 86 for genotype 3/3a, 50 for genotype 4/4a/4c/4d). Testing of subjects at high risk for HCV and with potential or actual impairment of the immune system identified 2 cases negative for anti-HCV and positive for HCV Ag on 361 hemodialyzed (0.6%) and 7 cases on 97 (7.2%) among transplant recipients. HCV Ag positivity anticipated anti-HCV seroconversion in all three cases of acute hepatitis C. Conclusions: HCV Ag may be used as reflex testing on anti-HCV positive individuals to confirm or exclude an active infection, and on subjects with acute hepatitis or belonging to high risk groups.
Journal of Clinical Microbiology, 2005
Here we compared two quantitative assays, the COBAS AMPLICOR HCV Monitor 2.0 assay (Roche Diagnostics) and the branched DNA-based VERSANT HCV RNA 3.0 assay (Bayer Diagnostics) for HCV RNA measurement in 344 samples derived from 120 patients with chronic genotype 1 HCV infection. The overall concordance between the results of the two tests was 95%, and the HCV RNA titers within the dynamic ranges of the assays correlated very well (r 2 ؍ 0.86). Furthermore, both tests performed equally well in determining an early viral response at week 1 or 4 during antiviral therapy. We also compared two qualitative HCV RNA detection assays: the COBAS AMPLICOR HCV 2.0 assay versus the transcription-mediated amplification (TMA)-based VERSANT HCV RNA qualitative assay. Stored samples from sustained responders to interferon-ribavirin therapy were retested by the HCV TMA assay and were found to contain no detectable HCV RNA, demonstrating complete concordance between the results of PCR and TMA. However, HCV RNA was detected by the TMA assay in end-of-treatment (ETR) samples from 33% of patients with relapses who were HCV RNA negative according to the COBAS AMPLICOR assay. This observation suggests that a TMA assay can lead to a more correct definition of the ETR response.
Detection and Quantification of HCV-RNA by RT-PCR among Anti-HCV Positive Patients
Journal of Armed Forces Medical College, Bangladesh
Introduction: The most common contemporary strategy to diagnose chronic hepatitis C virus (HCV) infection consists of initial screening with an HCV enzyme immunoassay (EIA) antibody test followed by supplemental testing of positive screening tests with a quantitative HCV RNA assay to confirm the positive EIA and to determine whether they have active or resolved hepatitis C infection. Objectives: To detect and quantify HCV-RNA by real-time polymerase chain reaction (real-time PCR) among anti-HCV positive patients and to identify the socio demographic factors among these patients. Materials and Methods: This was a descriptive type of cross-sectional study which was conducted in Combined Military Hospital and Armed Forces Institute of Pathology, Dhaka cantonment. A total of 108 anti-HCV positive patients by enzyme-linked immunosorbent assay (ELISA), who were clinically suspected and advised for anti-HCV test, were selected randomly for the study and subjected to do HCV-RNA analysis dur...