Clinical utility of total HCV core antigen quantification: a new indirect marker of HCV replication

Reducing hepatitis C diagnostic disparities with a fully automated deep learning-enabled microfluidic system for HCV antigen detection

Viral hepatitis remains a major global health issue, with chronic hepatitis B (HBV) and hepatitis C (HCV) causing approximately 1 million deaths annually, primarily due to liver cancer and cirrhosis. More than 1.5 million people contract HCV each year, disproportionately affecting vulnerable populations, including American Indians and Alaska Natives (AI/AN). While direct-acting antivirals (DAAs) are highly effective, timely and accurate HCV diagnosis remains a challenge, particularly in resource-limited settings. The current two-step HCV testing process is costly and time-intensive, often leading to patient loss before treatment. Point-of-care (POC) HCV antigen (Ag) testing offers a promising alternative, but no FDA-approved test meets the required sensitivity and specificity. To address this, we developed a fully automated, smartphone-based POC HCV Ag assay using platinum nanoparticles, deep learning image processing, and microfluidics. With an overall accuracy of 94.59%, this cost-effective, portable device has the potential to reduce HCV-related health disparities, particularly among AI/AN populations, improving accessibility and equity in care.

Disposable and sensitive electrochemical magneto-immunosensor for point-of-care HCV diagnostics: Targeting HCVcAg, the active viremia biomarker, in patient samples

Early detection of hepatitis C virus (HCV) infection is crucial for eliminating this silent killer, especially in resource-limited settings. HCV core antigen (HCVcAg) represents a promising alternative to the current "gold standard" HCV RNA assays as an active viremia biomarker. Herein, a highly sensitive electrochemical magneto-immunosensor for the HCVcAg was developed. The biosensing strategy involved capturing HCVcAg using antibody-coated magnetic beads, followed by a sandwich immunoassay before electrochemical detection on disposable screen-printed electrodes. To achieve signal amplification and consequent enhanced sensitivity, the antigen-antibody reaction was detected with a biotinylated polyclonal antibody subsequently labelled with a streptavidin poly horseradish peroxidase conjugate followed by amperometric detection via a hydroquinone/hydrogen peroxide system. The developed biosensor exhibited a cathodic current variation directly proportional to the HCVcAg concentration over a wide range (0.1-500 ng/mL), with a detection limit of 10 pg/mL. Moreover, it successfully discriminated healthy control human plasma samples from HCVcAg-spiked samples, showed no interference from endogenous plasma constituents or cross-reactivity with other viruses tested, and possessed excellent percentage recoveries of HCVcAg (≥92.83%), demonstrating high specificity. The proposed bioplatform remained stable for at least ten days and showed excellent clinical performance in detecting HCVcAg across a cohort of thirty-six plasma and serum samples from active hepatitis C cases, and healthy individuals, with results matching those previously obtained using clinically validated qPCR and serological testing. In summary, this biosensor provides a simple, rapid and economic alternative to other available techniques such as ELISA and qPCR for early diagnosis of HCV infection.

Development of a Lateral Flow Assay for the Detection of the Hepatitis C Virus Core Antigen

BACKGROUND

Hepatitis C virus (HCV) infection remains a global health challenge, with millions of people affected annually. Current diagnostic methods, reliant on antibody screening and viral RNA detection, are complex, costly, and often inaccessible, particularly in resource-limited settings.

AIM

Development of a lateral flow immunochromatography-based assay for detecting the highly conserved hepatitis C core antigen (HCVcAg).

METHODS

The assay relies on the interaction of four highly specific and cross-reactive monoclonal antibodies with recombinant HCVcAg from five different genotypes in a double antibody sandwich format. Latex and colloidal gold were evaluated as detector nanoparticles.

RESULTS

Extensive evaluation of 32 antibody combinations led to identifying the most sensitive antibody pairs. The chosen assay, named LN17, demonstrated a target sensitivity of 10 ng/strip, with potential clinical implications for detecting HCV. Furthermore, the study examined matrix effects in serum samples, providing valuable insights for future clinical application.

CONCLUSIONS

The developed assay holds promise as a rapid, cost-effective, and user-friendly tool to enhance accessibility to hepatitis C screening, especially in high-risk populations and resource-limited environments.

Multifunctionalized flower-like gold nanoparticles with high chemiluminescence for label-free sensing of the hepatitis C virus core protein

Developing functionalized nanomaterials with strong chemiluminescence (CL) properties is highly significant for ultrasensitive bioanalysis. Here, we report chitosan (CS), luminol, and Co²⁺-functionalized flower-like gold nanoparticles (Co²⁺/CS/Lum/AuNFs) with strong CL for the label-free sensing of the HCV core protein (HCVcp). The Co²⁺/CS/Lum/AuNFs exhibited a greatly enhanced CL emission at around 425 nm, which is 50 times stronger than that of CS/Lum/AuNFs, and is superior to other commonly reported CL nanomaterials. The HCVcp aptamer (HCVcp-apt) further functionalized the surface of the Co²⁺/CS/Lum/AuNFs through electrostatic interactions blocked the Co²⁺ catalytic site, depressing the CL. Owing to the high affinity of HCVcp for the HCVcp-apt, the presence of HCVcp predominated its binding and effectively separated the HCVcp-apt from the surface of the Co²⁺/CS/Lum/AuNFs, so that the CL intensity was significantly enhanced. As the results showed, the HCVcp-apt/Co²⁺/CS/Lum/AuNFs were successfully used to detect the HCVcp in human serum samples with a linear range from 0.50 ng mL^-1 to 1.00 μg mL^-1, a detection limit of 0.16 ng mL^-1 and an excellent selectivity over other analogs. The strategy is universal for the development of the ultrasensitive detection of other proteins in the field of early disease diagnostics.

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

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

One-step diagnosis strategy together with multidisciplinary telematics referral perform an effective approach for identifying and treating patients with active Hepatitis C infection

INTRODUCTION AND OBJECTIVES

Implementation of a one-step strategy for diagnosis of active Hepatitis C virus (HCV) infection would encourage the early diagnosis and reduce the time to access antiviral treatments. The aim of this study was to evaluate the impact of a HCV one-step diagnosis compared to the traditional two-step protocol in terms of the time required for patients to be seen by specialists and the time taken to start antiviral treatment.

MATERIAL AND METHODS

A comparative study was carried out to assess two diagnostic algorithms (one-step and two-step) for active HCV infection. Serological markers were quantified using the same serum sample to determine both anti-HCV antibodies (HCV-Ab) and HCV core antigen (HCV-cAg) by Architect i2000 SR kit. In this period, a multidisciplinary procedure was started for telematics referral of viremic patients.

RESULTS

One-step approach reduced the time required for patient HCV diagnosis, referral to a specialist, access to treatment, and eliminated the loss of patients to follow-up. Significant differences were observed between one-step and two-step diagnosis methods in the time required for patients to be seen by a specialist (18 days [Interquartile range (IQR) = 14-42] versus 107 days [IQR = 62-148]) and for the initiation of treatment (54 days [IQR = 43-75] versus 200 days [IQR = 116-388]), mainly for patients with advanced fibrosis (35 days [IQR = 116-388] versus 126 days [IQR = 152-366]).

CONCLUSIONS

Use of HCV-cAg has proven to be a useful tool for screening patients with active hepatitis C. The development of a multidisciplinary protocol for the communication of results improved the efficiency of the care process.

Ultrasensitive electrochemical detection of hepatitis C virus core antigen using terminal deoxynucleotidyl transferase amplification coupled with DNA nanowires

Early diagnosis of hepatitis C virus (HCV) infection is essential to prevent disease from spreading and progression. Herein, a novel electrochemical biosensor was developed for ultrasensitive detection of HCV core antigen (HCVcAg) based on terminal deoxynucleotidyl transferase (TdT) amplification and DNA nanowires (DNW). After sandwich-type antibody-antigen recognition, the antibody-conjugated DNA was pulled to the electrode surface and further extended into a long DNA sequence by robust TdT reaction. Then, large numbers of methylene blue-loaded DNW (MB@DNW) as signal labels are linked to the extended DNA sequence. This results in an amplified electrochemical signal for HCVcAg determination, typically measured at around -0.25 V (Ag/AgCl). Under the optimum conditions, the proposed biosensor achieved a wide linear range for HCVcAg from 0.1 to 312.5 pg/mL with a low limit of detection of 32 fg/mL. The good practicality of the biosensor was demonstrated by recovery experiment (recoveries from 98 to 104% with RSD of 2.5-4.4%) and comparison with enzyme-linked immunosorbent assay (ELISA). Given the highlighted performance, the biosensor is expected to act as a reliable sensing tool for HCVcAg determination in clinics. Schematic representation of the ultrasensitive electrochemical biosensor based on terminal deoxynucleotidyl transferase (TdT) amplification linked with methylene blue-loaded DNA nanowires (MB@DNW), which can be applied to the determination of hepatitis C virus core antigen (HCVcAg) in clinical samples. dTTPs, 2'-deoxythymidine 5'-triphosphate.

Detection of hepatitis C virus core antigen as an alternative method for diagnosis of hepatitis C virus infection in blood donors negative for hepatitis C virus antibody

BACKGROUND

Screening of blood donors in many countries is based on the use of serologic assays to detect specific anti-HCV antibodies (HCV Ab), but it lacks detection sensitivity. So, HCV RNA detection using the current gold standard real-time PCR is a must to rule out HCV infection with the main disadvantage being of high cost. HCV core antigen (HCV-c-Ag) immunoassay is proposed as a more cost efficient alternative to HCV RNA detection with PCR.

AIM

To evaluate the effectiveness of HCV-c-Ag detection as a cheap alternative to HCV RNA (PCR) in diagnosis of HCV infection in blood donors who are HCV Ab negative.

METHODS AND RESULTS

One hundred eighty-six volunteer blood donors who tested negative for HCV Ab were examined for HCV-c-Ag. Seven cases out of these 186 cases were HCV-c-Ag positive (4%). HCV RNA detection (PCR technique) was done to 30 cases (seven cases who test positive for HCV-c-Ag and 23 cases who test negative). Six out of the seven cases who were HCV-c-Ag positive (86%) were HCV RNA positive. Twenty-two cases out of the 23 cases who were HCV-c-Ag negative (96%) were HCV RNA negative.

CONCLUSION

HCV-c-Ag detection is an efficient method for diagnosis of HCV infection during screening of blood donors with high specificity (95.6%) and high negative predictive value (95.6%).

Design of a novel rapid immunoassay for simultaneous detection of hepatitis C virus core antigen and antibodies

HCV is a potential cause of viral hepatitis, which leads to blood-borne chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Anti-HCV antibody detection assays detect HCV infection after approximately 70 days. HCV core antigen can be detected much earlier than anti-HCV antibodies. However, it disappears soon after the appearance of anti-HCV antibodies. Thus, there is a need for a rapid assay for simultaneous detection of HCV core antigen and anti-HCV antibodies for early diagnosis of HCV infection. A rapid diagnostic assay (HCV Ag-Ab Combo) for simultaneous detection of HCV core antigen and anti-HCV antibodies for early diagnosis of HCV infection was developed. HCV Ag-Ab Combo was evaluated in order to determine its potential for detection of HCV infection earlier than anti-HCV antibody detection assays. We compared the sensitivity of the newly developed assay with anti-HCV antibody detection assays (ELISA [HCV Ab ELISA] and rapid test [HCV Ab Rapid]) and HCV core antigen/anti-HCV antibody detection ELISA (HCV Ag-Ab ELISA). This study included 11 samples that were found positive in HCV RNA detection and HCV Ag-Ab ELISA but negative in HCV antibody detection assays (HCV Ab ELISA and rapid), 10 samples that were found positive in HCV Ag-Ab ELISA and HCV Ab ELISA but negative in HCV Ab Rapid, 69 samples that were found positive in HCV Ag-Ab ELISA, HCV Ab ELISA, and HCV Ab Rapid, and 509 samples that were found negative in HCV Ag-Ab ELISA, HCV Ab ELISA, and HCV Ab Rapid. Three seroconversion panels, PHV 913, PHV 911 (M) and PHV904-00-1.0, and a HCV RNA genotype qualification panel (2400-0182) acquired from Seracare Life Sciences (USA) were also tested. HCV Ag-Ab Combo showed a combined sensitivity and specificity of 100% when tested with 90 samples that were positive for HCV by HCV Ag-Ab ELISA and 509 HCV-negative samples. Its positive predictive value (PPV) and negative predictive value (NPV) were found to be 100%. It detected HCV infection approximately 7 to 12 days earlier than the HCV Ab detection assays, and its performance was not affected when testing different genotypes of HCV. HCV Ag-Ab Combo did not detect HCV infection as early as HCV RNA or HCV Ag-Ab ELISA. HCV Ag-Ab Combo provided a significant improvement for the early detection of HCV infection during the preseroconversion phase when compared with anti-HCV antibody detection assays. It could be a useful screening assay, and an alternative to HCV RNA detection or HCV Ag-Ab ELISA when nucleic acid technologies cannot be implemented.

Implications of grey zone results for routine hepatitis C virus screening with the ARCHITECT HCV-Ag assay

AIMS

Hepatitis C virus antigen (HCV-Ag) detection requires retesting for samples with grey zone results (GzR), adding cost and time and decreasing reliability. Our aim in this study was to evaluate the frequency and significance of GzR during the use of the automated Architect HCV-Ag assay in routine clinical practice.

METHODS AND RESULTS

We studied HCV-Ag levels in 952 serum samples using the ARCHITECT HCV-Ag assay. GzR were detected in 33 samples; 25 were reactive on retesting and 19 were anti-HCV positive. Seventeen of these 19 samples were tested for HCV-RNA and were all reactive (viral loads <10⁴  IU ml^-1 ). The remaining six samples were anti-HCV nonreactive and had undetectable HCV-RNA. Eight GzR samples were nonreactive on retesting, seven were anti-HCV nonreactive (three underwent HCV-RNA quantification and were all nonreactive), and one was anti-HCV reactive (HCV-RNA nonreactive). No significant differences were found on comparing HCV-Ag values.

CONCLUSIONS

Grey zone results found to be negative on retesting do not need additional technique testing, except in donor screening scenarios, where the use of molecular methods would be advisable.

SIGNIFICANCE AND IMPACT OF THE STUDY

 The proposed diagnostic algorithm confirms that, eventhough GzR occur, hepatitis C virus antigen is a robust alternative to HCV-RNA detection in the active detection of infections.

Approaches for simplified HCV diagnostic algorithms

Introduction

In 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.

Methods

Published 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.

Results

Several 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.

Conclusions

Despite 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.

Plasmonic nanoplatform for point-of-care testing trace HCV core protein

Early diagnosis of hepatitis C virus (HCV) infection is still urgently desired as there is a global healthy burden and no vaccine available. In this work, a plasmonic nanoplatform was engineered with catalytic hairpin assembly (CHA) amplification reaction specifically of HCV core protein (HCVcp), G-quadruplex/hemin DNAzyme and nanofibrous membrane together. HCVcp was detected in whole serum at the ultralow concentration of 1.0 × 10^-4 pg/mL with naked eye. By testing serum samples from 30 donors with different viral loads, detection sensitivity of the plasmonic nanoplatform turned out to be much better than that of the commercial ELISA kit. In addition, the plasmonic nanoplatform exhibited high specificity, excellent reusability and long-term stability. Naked-eye detection based on the plasmonic nanoplatform is expected to have potential applications in point-of-care testing (POCT) and early diagnosis of hepatitis C and other infectious diseases.

Hepatitis C virus antigens enzyme immunoassay for one-step diagnosis of hepatitis C virus coinfection in human immunodeficiency virus infected individuals

BACKGROUND

Current diagnosis of hepatitis C virus (HCV) infection requires two sequential steps: testing for anti-HCV followed by HCV RNA PCR to confirm viremia. We have developed a highly sensitive and specific HCV-antigens enzyme immunoassay (HCV-Ags EIA) for one-step diagnosis of viremic HCV infection.

AIM

To assess the clinical application of the HCV-Ags EIA in one-step diagnosis of viremic HCV infection in human immunodeficiency virus (HIV)-coinfected individuals.

METHODS

The study blindly tested HCV-Ags EIA for its performance in one-step diagnosing viremic HCV infection in 147 sera: 10 without HCV or HIV infection; 54 with viremic HCV monoinfection; 38 with viremic HCV/HIV coinfection; and 45 with viremic HCV and non-viremic HIV coinfection.

RESULTS

Upon decoding, it was 100% accordance of HCV-Ags EIA to HCV infection status by HCV RNA PCR test. In five sera with HCV infection, HCV RNA was as low as 50-59 IU/mL, and four out of five tested positive for HCV-Ags EIA. Likewise, it was also 100% accordance of HCV-Ags EIA to HCV infection status by HCV RNA PCR in 83 sera with HCV and HIV coinfection, regardless if HIV infection was active or not.

CONCLUSION

The modified HCV-Ags EIA has a lower detection limit equivalent to serum HCV RNA levels of approximately 100 IU/mL. It is highly sensitive and specific in the setting of HIV coinfection, regardless of HIV infection status and CD4 count. These data support the clinical application of the HCV-Ags EIA in one-step diagnosis of HCV infection in HIV-infected individuals.

Molecular Microbiology

Background

Nucleic acid (NA) amplification techniques are now commonly used to diagnose and manage patients with infectious diseases. The growth in the number of Food and Drug Administration–approved test kits and analyte-specific reagents has facilitated the use of this technology in clinical laboratories. Technological advances in NA amplification techniques, automation, NA sequencing, and multiplex analysis have reinvigorated the field and created new opportunities for growth. Simple, sample-in, answer-out molecular test systems are now widely available that can be deployed in a variety of laboratory and clinical settings. Molecular microbiology remains the leading area in molecular pathology in terms of both the numbers of tests performed and clinical relevance. NA-based tests have reduced the dependency of the clinical microbiology laboratory on more traditional antigen detection and culture methods and created new opportunities for the laboratory to impact patient care.

Content

This chapter reviews NA testing as it applies to specific pathogens or infectious disease syndromes, with a focus on those diseases for which NA testing is now considered the standard of care and highlights the unique challenges and opportunities that these tests present for clinical laboratories.

Monitoring the treatment of hepatitis C with directly acting antivirals by serological and molecular methods

AIM

To evaluate the potential value of using a serological assay to quantitate the hepatitis C virus core antigen (HCV-Ag) when monitoring patients with chronic hepatitis C being treated with direct-acting antivirals (DAAs).

METHODS

Ninety-six patients treated with DAAs, either alone (91) or in combination with PEG interferon (5), were tested for HCV-RNA and for HCV-Ag at baseline and at weeks 2, 4, 8 and 12 during treatment and 12 weeks after completion. The concordance and correlation between the viral parameters as well as the respective kinetics during and after treatment were evaluated.

RESULTS

A sustained viral response (SVR) was achieved in 82 patients (91%), whereas 11 relapsed (R) and 1 showed a virological breakthrough while receiving treatment. HCV-RNA and HCV-Ag showed good concordance (kappa = 0.62) and correlation. No significant differences between SVR and R was observed in either assay at 2 and 4 weeks after the start of treatment. At 8 weeks, HCV-Ag showed higher accuracy than HCV-RNA (AUC: 0.74 vs. 0.55) and there was a significantly greater decrease from baseline in SVR than in R (4.01 vs. 3.36 log10; p<0.05).

CONCLUSIONS

Monitoring during treatment with DAAs by using either HCV-RNA or HCV-Ag has only a limited predictive value for SVR. Since those assays are equivalent for identifying a virological relapse, HCV-Ag may be preferred from an economical and organizational perspective.

HCV core antigen is an alternative marker to HCV RNA for evaluating active HCV infection: implications for improved diagnostic option in an era of affordable DAAs

The core antigen of the hepatitis C virus (HCV Ag) presents an alternative marker to HCV RNA when screening patients for HCV viremia. This study sought to evaluate the utility of HCV Ag as a marker to assess active HCV infection in individuals residing in an HCV-endemic area. From 298 HCV-seropositive individuals evaluated for the presence of anti-HCV antibody, HCV Ag and HCV RNA, anti-HCV antibody was detected in 252 individuals (signal-to-cutoff ratios ≥5), HCV RNA was detected in 222 individuals (88%), and HCV Ag was reactive (≥3 fmol/L) in 220 individuals (87%). HCV genotype 1, 3, and 6 were identified. HCV Ag significantly correlated with HCV RNA irrespective of HCV genotype and/or HBV co-infection (log HCV RNA = 2.67 + 0.95 [log HCV Ag], R2 = 0.890, p < 0.001). To predict HCV viremia (HCV Ag ≥ 3 fmol/L), the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 99%, 99%, 100%, 100% and 97%, respectively. We concluded that HCV Ag was a good surrogate marker for HCV RNA and could be used to diagnose active HCV infection in a resource-limited setting. As a result, a cost-effective strategy for screening and identifying active HCV carriers using HCV Ag detection would enable more patients access to efficacious and increasingly affordable direct-acting antivirals (DAAs) for the treatment of HCV infection.

HCV Ag quantification as a one-step procedure in diagnosing chronic hepatitis C infection in Cameroon: the ANRS 12336 study

INTRODUCTION

The diagnostic procedure for chronic hepatitis C infection (CHC) usually combines anti-HCV antibody (HCV-Ab) and HCV-RNA measurement. Quantifying HCV core antigen (cAg) as a one-step procedure could shorten the diagnostic process. We aimed to assess the performance of cAg quantification in diagnosing CHC and how it is influenced by concomitant HIV or HBV infections.

METHODS

The cAg was quantified by an automated assay (Abbott Diagnostics) in 465 HCV-Ab negative serum samples and 544 HCV-RNA positive serum samples (n = 1009) collected in patients from the Pasteur Center in Cameroon, some of whom were infected by HBV or HIV. Its performance was evaluated in comparison to the gold standard (ELISA or PCR) by estimating its sensitivity (Se) and specificity (Sp), and by comparing the area under ROC (AUROC) curves in each patient population: HCV mono-infected, HCV-HBV and HIV-HCV co-infected.

RESULTS

Among the 465 HCV-Ab negative patients, 51 and 79 were HIV- and HBV-infected, respectively, whereas among the 544 patients with CHC, 27 and 28 were HIV- and HBV-infected, respectively. The Spearman ρ correlation coefficient between cAg and HCV-RNA was 0.75 (p < 0.00001). The assay had a sensitivity of 95.7% (95% CI: 93.2-97.5) and a specificity of 99.7% (95% CI: 98.1-10) in diagnosing CHC, corresponding to an AUROC of 0.99 (95% CI: 0.98-1.0). Being HIV- or HBV-infected did not impact the performance of cAg (Se = 96.4%, Sp = 96.2% and AUROC = 0.98 (95% CI: 0.95-1.0) in the HBV group, Se = 100%, Sp = 88.2% and AUROC = 0.99 (95% CI: 0.97-1.0) in the HIV group, p between AUROC = 0.69).

CONCLUSIONS

The cAg quantification displayed a high specificity and sensitivity for the diagnosis of CHC in Cameroon, and its performance was not significantly modified by a concomitant HIV or HBV infection. In the context of CHC elimination on a global scale, using cAg quantification as a screening tool to directly identify CHC could be a reliable tool in a "test and treat" strategy.

Can Hepatitis C Virus Antigen Testing Replace Ribonucleic Acid Polymearse Chain Reaction Analysis for Detecting Hepatitis C Virus? A Systematic Review

The complexity and cost of current diagnostics for hepatitis C virus (HCV) may act as a prevention to the scale-up of treatment in the developing world. Currently, ribonucleic acid (RNA)-polymerase chain reaction tests are the gold standard. However, there is potential for the use of simpler and cheaper antigen tests to confirm HCV infection in different clinical settings. We evaluated the sensitivity and specificity of antigen assays. This was compared with the reference-standard RNA assays. A subanalysis also assessed Architect core antigen test, which is the only commercially available antigen test on the market. In 24 datasets, evaluating HCV-antigen assays in 8136 samples, the percentage of HCV-antigen positive, HCV-RNA negative was 0.57%. The percentage HCV-antigen negative, HCV-RNA positive was 3.52%. There is strong evidence that antigen detection performs as well as RNA-based assays for HCV management. The use of antigen tests could improve access to HCV care in underresourced healthcare settings.

HCV core antigen as an alternate test to HCV RNA for assessment of virologic responses to all-oral, interferon-free treatment in HCV genotype 1 infected patients

In light of the advances in HCV therapy, simplification of diagnosis confirmation, pre- treatment diagnostic workup and treatment monitoring is required to ensure broad access to interferon-free therapies. HCV core antigen (HCV cAg) testing is rapid, giving results in approximately 60min, and less expensive than HCV RNA methods. While extensive data on the analytical performance of HCV cAg relative to RNA or comparisons in longitudinal studies of patients on interferon based (response guided) therapy there is very limited data on the relative performance of HCV cAg in diagnosis and monitoring patients receiving all-oral interferon free regimens. Furthermore, there is no data in the literature that describes the specificity of HCV cAg in patients with resolved HCV infection i.e. anti-HCV positive/HCV RNA negative. In this study a total of 1201 plasma samples from the 411 HCV genotype 1 subjects with a HCV RNA viral load >50,000IU/ml who enrolled in a clinical trial with ombitasvir, ritonavir-boosted paritaprevir and dasabuvir, with or without ribavirin were retrospectively tested in a blinded fashion with HCV cAg test and results were compared to HCV RNA levels. The specificity of the HCV cAg test was also evaluated in anti-HCV positive but HCV RNA negative samples. Overall concordance between HCV cAg and HCV RNA was 98.6% while concordance in pre-treatment samples was 99.5% (409/411; n=2 HCV RNA pos. with viral loads>3 Mill IU/ml but HCV cAg neg.) and 99.24% in post treatment week 12 samples (391/394; n=2 HCV RNA pos.<25IU/ml and n=1 HCV RNA pos. 2180IU/ml). Specificity in anti-HCV positive HCV RNA negative samples tested was 100%.

Performance comparison of new generation HCV core antigen test versus HCV RNA test in management of hepatitis C virus infection

The study has evaluated the performance of HCV core antigen (Cag) test by comparing HCV RNA PCR assay which is considered the gold standard for management of HCV infection. Totally, 132 samples sent for HCV RNA (real-time PCR) test were included in the study. Anti-HCV antibody test and HCV Cag test were performed by chemiluminescent enzyme immunoassay (CMEI). Anti-HCV test was positive in all samples. HCV RNA was detected in 112/132 (84.8%) samples, and HCV Cag in 105/132 (79.5%). The most common HCV genotype was genotype 1 (86%). Considering the HCV RNA test as gold standard; the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of Cag test were found to be 93.75%, 100%, 100%, 74.07% and 94.69%, respectively, and paired test results were detected as highly concordant. A high level of correlation was seen between HCV RNA and Cag tests, however, the concordance between the two tests appeared to be disrupted at viral loads lower than 10³IU/mL. On the contrary, the correlation reached significance for the values higher than 10³IU/mL. Viral loads were in the 17-2500IU/mL range for the negative results for Cag test. Pearson's correlation coefficient revealed a considerably high correlation. The concordance between HCV RNA and Cag tests was disrupted under a viral load lower than 10³IU/mL. Therefore, it would be appropriate to consider cost effectiveness, advantages and limitations of the HCV RNA and Cag tests during the decision on which method to use for patient management.

Hepatitis C virus infection

Hepatitis C virus (HCV) is a hepatotropic RNA virus that causes progressive liver damage, which might result in liver cirrhosis and hepatocellular carcinoma. Globally, between 64 and 103 million people are chronically infected. Major risk factors for this blood-borne virus infection are unsafe injection drug use and unsterile medical procedures (iatrogenic infections) in countries with high HCV prevalence. Diagnostic procedures include serum HCV antibody testing, HCV RNA measurement, viral genotype and subtype determination and, lately, assessment of resistance-associated substitutions. Various direct-acting antiviral agents (DAAs) have become available, which target three proteins involved in crucial steps of the HCV life cycle: the NS3/4A protease, the NS5A protein and the RNA-dependent RNA polymerase NS5B protein. Combination of two or three of these DAAs can cure (defined as a sustained virological response 12 weeks after treatment) HCV infection in >90% of patients, including populations that have been difficult to treat in the past. As long as a prophylactic vaccine is not available, the HCV pandemic has to be controlled by treatment-as-prevention strategies, effective screening programmes and global access to treatment.

Hepatitis C treatment: where are we now?

Chronic hepatitis C infection affects millions of people worldwide and confers significant morbidity and mortality. Effective treatment is needed to prevent disease progression and associated complications. Previous treatment options were limited to interferon and ribavirin (RBV) regimens, which gave low cure rates and were associated with unpleasant side effects. The era of direct-acting antiviral (DAA) therapies began with the development of first-generation NS3/4A protease inhibitors in 2011. They vastly improved outcomes for patients, particularly those with genotype 1 infection, the most prevalent genotype globally. Since then, a multitude of DAAs have been licensed for use, and outcomes for patients have improved further, with fewer side effects and cure rates approaching 100%. Recent regimens are interferon-free, and in many cases, RBV-free, and involve a combination of DAA agents. This review summarizes the treatment options currently available and discusses potential barriers that may delay the global eradication of hepatitis C.

Clinical Significance of Two Real-Time PCR Assays for Chronic Hepatitis C Patients Receiving Protease Inhibitor-Based Therapy

The aim of this study was to determine the efficacy of two hepatitis C virus (HCV) real-time PCR assays, the COBAS AmpliPrep/COBAS TaqMan HCV test (CAP/CTM) and the Abbott RealTime HCV test (ART), for predicting the clinical outcomes of patients infected with HCV who received telaprevir (TVR)-based triple therapy or daclatasvir/asunaprevir (DCV/ASV) dual therapy. The rapid virological response rates in patients receiving TVR-based triple therapy were 92% (23/25) and 40% (10/25) for CAP/CTM and ART, respectively. The false omission rate (FOR) of ART was 93.3% (14/15), indicating that CAP/CTM could accurately predict clinical outcome in the early phase. In an independent examination of 20 patients receiving TVR-based triple therapy who developed viral breakthrough or relapse, the times to HCV disappearance by ART were longer than by CAP/CTM, whereas the times to HCV reappearance were similar. In an independent experiment of WHO standard HCV RNA serially diluted in serum containing TVR, the analytical sensitivities of CAP/CTM and ART were similar. However, cell cultures transfected with HCV and grown in medium containing TVR demonstrated that ART detected HCV RNA for a longer time than CAP/CTM. Similar results were found for 42 patients receiving DCV/ASV dual therapy. The FOR of ART was 73.3% (11/15) at week 8 after initiation of therapy, indicating that ART at week 8 could not accurately predict the clinical outcome. In conclusion, although CAP/CTM and ART detected HCV RNA with comparable analytical sensitivity, CAP/CTM might be preferable for predicting the clinical outcomes of patients receiving protease inhibitor-based therapy.

Utility of enzyme-linked immunosorbent assays to test core antigen in the diagnosis and antiviral therapy management of hepatitis C virus infections

In this study, we evaluate the performance of the enzyme-linked immunosorbent assays (ELISAs) for HCV Ag detection in the diagnosis and antiviral therapy management of HCV infections. For the diagnosis of an active HCV infection, the limit of detection of HCV Ag corresponding to HCV RNA level was approximately 7300 IU/mL; the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of HCV-Ag were 88.96, 100, 100, and 91.33%, respectively. The Pearson's correlation coefficient between HCV Ag and HCV RNA was 0.891. All patients with negative HCV Ag at interferon-α2α/ribavirin therapy week 1 achieved a sustained viral response (SVR), and the PPV was 100%; whereas in patients with positive HCV Ag at therapy weeks 12, the NPV for achieving non-response (NR) was 100%. The results showed that ELISAs for HCV Ag detection could be cost effectively applied to diagnose and evaluate the response to antiviral therapy for HCV infections.

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 >10⁵IU/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.

A highly specific and sensitive hepatitis C virus antigen enzyme immunoassay for One-step diagnosis of viremic hepatitis C virus infection

The current standard in diagnosing hepatitis C virus (HCV) infection requires two sequential steps: anti-HCV test to screen, followed by HCV RNA reverse-transcription polymerase chain reaction to confirm viremic HCV (V-HCV) infection. HCV core antigen tests provided potential for possible one-step diagnosis. However, low sensitivity and specificity limit their clinical utility. The present study developed a novel HCV antigens enzyme immunoassay (HCV-Ags EIA) and assessed its sensitivity, specificity, and utility for one-step diagnosis of V-HCV infection using 365 serum specimens, including 176 without and 189 with V-HCV infection. First, we confirmed the presence of HCV nonstructural proteins 3, 4b, and 5a besides HCV core antigen during HCV infection and developed a novel HCV-Ags EIA through simultaneous detection of all four HCV proteins. For the first time, the present study demonstrated that serum sample denaturation decreases the test specificity due to release of HCV-Ags sequestered in HCV immune complexes and should not be used in any HCV-Ags, including all the current HCV core antigen assays. On the other hand, using sample nondenaturation, the HCV-Ags EIA results showed 98.9% specificity and 100% sensitivity compared to serum anti-HCV and HCV RNA reverse-transcription polymerase chain reaction results. Using serum sample dilution, and nondenaturation, the lowest limits of detection of the HCV-Ags EIA were equivalent to serum HCV RNA levels of approximate 150-250 IU/mL.

CONCLUSIONS

The highly specific and sensitive HCV-Ags EIA developed in the present study has the lowest limit of detection equivalent to serum HCV RNA levels of 150-250 IU/mL; using nondenaturation of serum samples, our HCV-Ags EIA reliably differentiated V-HCV infection from resolved HCV infection, accomplishing screening and diagnosis of V-HCV infection in one step. (Hepatology 2016;64:415-424).

HCV core protein binds to gC1qR to induce A20 expression and inhibit cytokine production through MAPKs and NF-κB signaling pathways

Hepatitis C virus (HCV) infection is characterized by a strong propensity toward chronicity. During chronic HCV infection, HCV core protein is implicated in deregulating cytokine expression that associates with chronic inflammation. A20 is known as a powerful suppressor in cytokine signaling, in this study, we explored the A20 expression in macrophages induced by HCV core protein and the involved signaling pathways. Results demonstrated that HCV core protein induced A20 expression in macrophages. Silencing A20 significantly enhanced the secretion of IL-6, IL-1β and TGF-β1, but not IL-8 and TNF. Additionally, HCV core protein interacted with gC1qR, but not TLR2, TLR3 and TLR4 in pull-down assay. Silencing gC1qR abrogated core-induced A20 expression. Furthermore, HCV core protein activated MAPK, NF-κB and PI3K/AKT pathways in macrophages. Inhibition of P38, JNK and NF-κB but not ERK and AKT activities greatly reduced the A20 expression. In conclusion, the study suggests that HCV core protein ligates gC1qR to induce A20 expression in macrophages via P38, JNK and NF-κB signaling pathways, which leads to a low-grade chronic inflammation during HCV infection. It represents a novel mechanism by which HCV usurps the host for persistence.

Association between IL28B polymorphism, TNFα and biomarkers of insulin resistance in chronic hepatitis C-related insulin resistance

TNFα has been shown to play a role in hepatitis C virus (HCV)-induced insulin resistance (IR). Polymorphism of the IL28B gene that encodes IFN-lambda 3 may be associated with IR through modulation of TNFα. The aim of this study was to investigate the relationship between IL28B rs12979860 genotype, the level of TNFα activation and the degree of IR in patients with chronic hepatitis C. One hundred and thirty-three nondiabetic genotype 1 HCV-infected patients with biopsy proven noncirrhotic hepatitis C were investigated for IR (using HOMA index), IL28B rs12979860 genotype and fasting circulating levels of soluble receptor 1 of TNFα (sTNFR1) and adipokines: leptin, adiponectin and IL-6. The HOMA-IR was positively correlated with serum levels of leptin (r = 0.35, P < 0.0001) and sTNFR1 (r = 0.35, P < 0.0001) but not with IL-6 or adiponectin. IL28B rs12979860 CC genotype was observed in 35% patients. Genotype CC and nongenotype CC patients were similar in terms of HOMA-IR (means 1.6 ± 0.9 vs 1.7 ± 1.4) and had similar circulating levels of sTNFR1 and adipokines. Independent factors associated with IR were ferritin (OR = 1.002, P = 0.02), leptin (OR = 1.06, P = 0.02) and sTNFR1 (OR = 7.9, P = 0.04). This study suggests that in nondiabetic, noncirrhotic, HCV genotype 1-infected patients, there is no relationship between IL28B rs12979860 genotype and HOMA-IR or sTNFR1 level. HCV-related IR may be mediated through TNFα independent of IL28B genotype.

Dried Blood Spots: A Tool to Ensure Broad Access to Hepatitis C Screening, Diagnosis, and Treatment Monitoring

BACKGROUND

With the advent of highly efficient antiviral therapies for hepatitis C virus (HCV) infection, providing broad access to diagnosis and care is needed. The dried blood spot (DBS) technique can be used to collect, store, and ship whole-blood specimens. Our goal was to assess the performance of standardized HCV diagnostic and monitoring tools in the analysis of DBS.

METHODS

Serum specimens and whole-blood specimens collected using the DBS technique from >500 patients were tested for virological markers used to diagnose and monitor HCV infection.

RESULTS

Enzyme immunoassay detection of anti-HCV antibodies in specimens from DBS was reliable after establishment of a new signal-to-cutoff ratio. HCV RNA was detected DBS from the vast majority of patients with active replication, but HCV RNA levels were substantially lower than in serum specimens, implying that only the presence or absence of HCV RNA or changes in the HCV RNA level should be taken into consideration for therapy. Detection of HCV core antigen in specimens from DBS was not a sensitive marker of chronic HCV infection. HCV genotype determination was possible in the vast majority of DBS.

CONCLUSIONS

This study shows that whole-blood specimens collected using the DBS technique can be confidently used to diagnose and monitor HCV infection. DBS could help improve access to care for HCV infection because they are suitable for use in large-scale screening programs, diagnosis, and therapeutic monitoring.

Evaluation of an antigen-antibody "combination" enzyme linked immunosorbent assay for diagnosis of hepatitis C virus infections

Background

Development of “combination” assays detecting in parallel, within a single test, Hepatitis C Virus (HCV) antigens and antibodies, not only reduces the window period in HCV-infection but also costs. Reduction of costs is important for developing countries where money and personal resources are limited.

Methods

We compared the Monolisa® HCV Antigen-Antibody Ultra (Bio-Rad Laboratories Limited, Marnes La Coquette, France) with the AXSYM HCV version 3.0 (Abbot Diagnostics, Germany)-the latter assay detecting only antibodies to HCV. Seventy three HCV-PCR positive and negative samples were tested.

Results

Although the two assays showed comparable results, two samples from a bone marrow transplant (BMT) patient of viral loads 7.8 × 10₅ and 8.9 × 10₆ IU/mL could not be detected by the Monolisa® HCV Antigen-Antibody Ultra assay. Failure to detect the two samples with viral loads considered above threshold of detection for antigen proteins suggested a lack of sensitivity by this assay to discover viral capsid protein in patient samples. Genotyping of these samples revealed genotype 1b, a HCV-subtype which is widespread and should thus be easily detected.

Conclusion

We conclude that although this assay depicts high sensitivity and specificity in detecting antibodies to HCV, it seems not to add further benefit in our study population to detect HCV infections by enhanced sensitivity due the potential contingency to trace viral capsid antigens.

Sensitivity of hepatitis C virus core antigen and antibody combination assays in a global panel of window period samples

BACKGROUND

Hepatitis C virus (HCV) antigen and antibody combination assays have been launched as a cost-effective alternative to nucleic acid testing (NAT) for reducing the antibody-negative window period (WP). Later, a HCV antigen chemiluminescence immunoassay (CLIA) became available.

STUDY DESIGN AND METHODS

A panel composed of 337 HCV NAT-yield samples that were characterized for viral load (VL) and genotype was used to compare the sensitivity of two combination enzyme-linked immunosorbent assays (Monolisa, Bio-Rad; and Murex, formerly Abbott) and a HCV antigen CLIA (Abbott). Analytic sensitivity was compared with HCV RNA detection using Ultrio (Grifols) by testing serial dilutions of 10 genotype (gt)1 to gt4 samples.

RESULTS

HCV antigen CLIA detected 92.4% of samples, whereas Monolisa and Murex detected 38.3 and 47.5%, respectively. In the HCV RNA VL range of 10(5) to 10(7) IU/mL, Monolisa and Murex detected 38% to 56% of gt1, 85% to 78% of gt2, and 21% to 37% of gt3. The overall geometric mean 50% limit of detection (range) of Ultrio on gt1 to gt4 dilution series was 3.5 (1.2-7.7) copies/mL, compared to 3.3 × 10(6) (4.4 × 10(5) -2.7 × 10(7) ), 3.4 × 10(6) (2.2 × 10(5) -4.2 × 10(7) ), and 2728 (415-7243) copies/mL for Monolisa, Murex, and HCV antigen CLIA, respectively.

CONCLUSION

Analytical sensitivity of NAT was on average 1 million- and 780-fold higher than combination assays and HCV antigen CLIA, respectively. Relative sensitivities of combination assays differed for genotypes with Murex being more sensitive for gt1 and gt3 and Monolisa more sensitive for gt2. Although being less sensitive than NAT, combination assays could be considered in resource-limited settings since they detect 38% to 47% of seronegative WP donations.

Evidence-based consensus on the diagnosis, prevention and management of hepatitis C virus disease

Hepatitis C virus (HCV) is a potent human pathogen and is one of the main causes of chronic hepatitis round the world. The present review describes the evidence-based consensus on the diagnosis, prevention and management of HCV disease. Various techniques, for the detection of anti-HCV immunoglobulin G immunoassays, detection of HCV RNA by identifying virus-specific molecules nucleic acid testings, recognition of core antigen for diagnosis of HCV, quantitative antigen assay, have been used to detect HCV RNA and core antigen. Advanced technologies such as nanoparticle-based diagnostic assays, loop-mediated isothermal amplification and aptamers and Ortho trak-C assay have also come to the front that provides best detection results with greater ease and specificity for detection of HCV. It is of immense importance to prevent this infection especially among the sexual partners, injecting drug users, mother-to-infant transmission of HCV, household contact, healthcare workers and people who get tattoos and piercing on their skin. Management of this infection is intended to eradicate it out of the body of patients. Management includes examining the treatment (efficacy and protection), assessment of hepatic condition before commencing therapy, controlling the parameters upon which dual and triple therapies work, monitoring the body after treatment and adjusting the co-factors. Examining the treatment in some special groups of people (HIV/HCV co-infected, hemodialysis patients, renal transplanted patients).

Reducing the neglected burden of viral hepatitis in Africa: strategies for a global approach

The burden of liver disease may dramatically increase in the near future in Africa, where screening and access to care and treatment are hampered by inadequate disease surveillance, lack of high-quality tools to assess chronic liver disease, and underestimated needs for human and financial resources. Chronic hepatitis may be considered as silent and neglected killer, fuelled by many years of global inertia from stakeholders and policy makers alike. However, the global battle against viral hepatitis is facing a new era owing to the advent of highly effective drugs, innovative tools for screening and clinical follow-up, and recent signs that governments, advocacy groups and global health organizations are mobilizing to advocate universal access-to-treatment. This review details the barriers to prevention, screening and treatment of viral hepatitis on the African continent, focuses on the urgent need for operational and research programmes, and suggests integrated ways to tackle the global epidemic.

Comparison of HCV core antigen and anti-HCV with HCV RNA results

BACKGROUND

The measurement of anti-HCV antibodies using immunological methods and the confirmation of viral nuclear acid based on molecular methods is important in diagnosis and follow-up of the HCV infection.

OBJECTIVES

In this study, we aimed to analyse HCV core Antigen positivity among anti-HCV antibody positive sera to determine the significance of testing of HCV core Ag for the laboratory diagnosis of HCV infection, by considering the correlation between serum HCV core Ag and HCV RNA levels.

METHODS

115 patients suspected of having hepatitis C and who were positive for anti-HCV antibody were investigated using chemiluminescent and molecular methods. Anti-HCV antibody, HCV core Ag and HCV RNA levels were detected by the Vitros ECiQ immunodiagnostic system, Architect i2000 system and RT-PCR, respectively.

RESULTS

The sensitivity, specificity, positive and negative predictive values and accuracy rate of HCV core Antigen assay were detected as 86.5%(83/96), 100%(19/19), 100%(83/83), 59.4%(19/32), 88.7%(102/115) respectively.

CONCLUSION

HCV core Ag assay could be used for diagnosis of HCV infection as it is easy to perform, cost-effective, has high specificity and positive predictive value. However, it should be kept in mind that it may have lack of sensitivity and negative predictive value.

Diagnostic tests for hepatitis C: Recent trends in electrochemical immunosensor and genosensor analysis

Hepatitis C is a liver disease that is transmitted through contact with the blood of an infected person. An estimated 150 million individuals worldwide have been chronically infected with the hepatitis C virus (HCV). Hepatitis C shows significant genetic variation in the global population, due to the high rate of viral RNA mutation. There are six variants of the virus (HCV genotypes 1, 2, 3, 4, 5, and 6), with 15 recorded subtypes that vary in prevalence across different regions of the world. A variety of devices are used to diagnose hepatitis C, including HCV antibody test, HCV viral load test, HCV genotype test and liver biopsy. Rapid, inexpensive, sensitive, and robust analytical devices are therefore essential for effective diagnosis and monitoring of disease treatment. This review provides an overview of current electrochemical immunosensor and genosensor technologies employed in HCV detection. There are a limited number of publications showing electrochemical biosensors being used for the detection of HCV. Due to their simplicity, specificity, and reliability, electrochemical biosensor devices have potential clinical applications in several viral infections.

Effectiveness of HCV core antigen and RNA quantification in HCV-infected and HCV/HIV-1-coinfected patients

Background

The measurement of hepatitis C virus core antigen (HCV-coreAg) has been shown to be an indicator of active HCV infection. The aim of the present study was 1) to investigate the stability and effectiveness of HCV-coreAg and HCV-RNA quantification in HCV infection with or without HIV-1 coinfection, 2) to explore the association between the HCV-coreAg/HCV-RNA (Ag/RNA) ratio and the immune status in chronic HCV/HIV-1-coinfected patients.

Methods

A longitudinal investigation comprised of 227 HCV-monoinfected (n = 129) and HCV/HIV-1-coinfected (n = 98) patients was initiated in August 2009, and 139 (73 with HCV monoinfection and 66 with HCV/HIV-1 coinfection) were followed up in August 2012. Both HCV core antigen and HCV RNA quantification were determined on this cryopreserved plasma. HCV core antigen and HCV RNA quantification were performed subsequently. In addition, an in vitro experiment investigating the possibility of degradation of HCV components (core antigen and RNA) were conducted.

Results

Significant and stable correlations (p < 0.001) were observed both in chronic HCV-monoinfected and HCV/HIV-1-coinfected patients over the 3-year observation. Coinfected patients with immunocompromised condition had a significantly higher (p < 0.05) Ag/RNA ratios than those patients with immunocompetent condition both at two time points (2009 and 2012). Moreover, the Ag/RNA ratios were negatively correlated with CD4+ T-cell counts (p < 0.001). An in vitro experiment investigated the possibility of the slower degradation of HCV particles under HIV-related immunocompromised condition was conducted and the data demonstrated that the Ag/RNA ratios were significantly higher in HIV-1-positive plasma than in healthy plasma (p = 0.005) in this study.

Conclusions

Our longitudinal study indicated that the HCV-coreAg presented comparable dynamics over time as HCV RNA in chronic HCV-infected patients. Meanwhile, the HCV-coreAg/HCV-RNA ratio was closely associated with immune status in HCV/HIV-1-coinfected patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0577-1) contains supplementary material, which is available to authorized users.

Tools for the diagnosis of hepatitis C virus infection and hepatic fibrosis staging

Hepatitis C virus (HCV) infection represents a major public health issue. Hepatitis C can be cured by therapy, but many infected individuals are unaware of their status. Effective HCV screening, fast diagnosis and characterization, and hepatic fibrosis staging are highly relevant for controlling transmission, treating infected patients and, consequently, avoiding end-stage liver disease. Exposure to HCV can be determined with high sensitivity and specificity with currently available third generation serology assays. Additionally, the use of point-of-care tests can increase HCV screening opportunities. However, active HCV infection must be confirmed by direct diagnosis methods. Additionally, HCV genotyping is required prior to starting any treatment. Increasingly, high-volume clinical laboratories use different types of automated platforms, which have simplified sample processing, reduced hands-on-time, minimized contamination risks and human error and ensured full traceability of results. Significant advances have also been made in the field of fibrosis stage assessment with the development of non-invasive methods, such as imaging techniques and serum-based tests. However, no single test is currently available that is able to completely replace liver biopsy. This review focuses on approved commercial tools used to diagnose HCV infection and the recommended hepatic fibrosis staging tests.

Assessment of total hepatitis C virus (HCV) core protein in HCV-related mixed cryoglobulinemia

Introduction

In hepatitis C virus (HCV)-related mixed cryoglobulinemia (MCG), the nonenveloped HCV core protein (HCV-Cp) is a constituent of the characteristic cold-precipitating immune complexes (ICs). A possible correlation between HCV-Cp, virologic, laboratory, and clinical parameters in both untreated MCG patients and those undergoing specific treatment was explored.

Methods

HCV-Cp was quantified by a fully automated immune assay. Correlations between HCV-Cp and HCV RNA, cryocrit, and virus genotype (gt) were investigated in 102 chronically HCV-infected MCG patients.

Results

HCV-Cp concentrations strongly correlated with HCV RNA levels in baseline samples. An average ratio of 1,425 IU and 12,850 IU HCV RNA per picogram HCV-Cp was estimated in HCV gt-1 and gt-2 patients, respectively. This equation allowed us to estimate that, on average, HCV-Cp was associated with the viral genome in only 3.4% of the former and in 35% of the latter group of patients. The direct relation between HCV-Cp and the cryocrit level suggests that the protein directly influences the amount of cryoprecipitate. Although the therapy with rituximab (RTX) as a single agent resulted in the enhancement of HCV-Cp levels, in patients treated with RTX in combination with a specific antiviral therapy (pegylated interferon-α plus ribavirin), the prompt and effective clearance of HCV-Cp was documented.

Conclusions

Our data provide evidence that HCV-Cp has a direct effect on the cold-precipitation process in a virus genotype-dependence in HCV-related MCG patients.

Hepatitis C virus RNA tests: performance attributes and their impact on clinical utility

The diagnostic market is driven by the burden of disease in the population and the ease or difficulty of disease diagnosis. The efficacy of available therapeutics determines the need for monitoring. Hepatitis C virus currently affects approximately 3% of the world's population, although the overall response rate to the best available therapies is 56%. Research regarding hepatitis C virus remains elusive due to lack of an efficient cell culture system. Diagnosis and monitoring of active hepatitis C virus infection therefore rely on sophisticated molecular tests. This review will focus on current molecular tests for hepatitis C virus RNA and the performance attributes that these tests require for accurate diagnosis and monitoring of infection.

Inhibition of hepatitis C virus production by aptamers against the core protein

Hepatitis C virus (HCV) core protein is essential for virus assembly. HCV core protein was expressed and purified. Aptamers against core protein were raised through the selective evolution of ligands by the exponential enrichment approach. Detection of HCV infection by core aptamers and the antiviral activities of aptamers were characterized. The mechanism of their anti-HCV activity was determined. The data showed that selected aptamers against core specifically recognize the recombinant core protein but also can detect serum samples from hepatitis C patients. Aptamers have no effect on HCV RNA replication in the infectious cell culture system. However, the aptamers inhibit the production of infectious virus particles. Beta interferon (IFN-β) and interferon-stimulated genes (ISGs) are not induced in virally infected hepatocytes by aptamers. Domains I and II of core protein are involved in the inhibition of infectious virus production by the aptamers. V31A within core is the major resistance mutation identified. Further study shows that the aptamers disrupt the localization of core with lipid droplets and NS5A and perturb the association of core protein with viral RNA. The data suggest that aptamers against HCV core protein inhibit infectious virus production by disrupting the localization of core with lipid droplets and NS5A and preventing the association of core protein with viral RNA. The aptamers for core protein may be used to understand the mechanisms of virus assembly. Core-specific aptamers may hold promise for development as early diagnostic reagents and potential therapeutic agents for chronic hepatitis C.

Advances in the Diagnosis and Monitoring of Hepatitis C Virus Infection

Hepatitis C virus (HCV) infection represents a major health problem worldwide. Approximately 350,000 people die every year from hepatitis C related diseases. Antiviral therapy is given to prevent such complications. Advances in serological and molecular assays greatly improved the diagnosis of hepatitis C virus infection and the management of chronically infected patients. Sensitive real-time PCR methods are currently used to monitor the response to antiviral therapy, to guide treatment decisions, and to assess the sustained virological response 24 weeks after the end of therapy. HCV genotyping is part of the pretreatment evaluation. Determination of HCV genotype is important both for tailoring antiviral treatment and for determining treatment duration. It predicts also response to therapy. With the recent introduction of the serine protease inhibitors telaprevir and boceprevir, approved for the treatment of genotype 1 chronic hepatitis C in combination with INF-a and ribavirin, subtyping has become clinically relevant. Indeed, subtypes 1a and 1b may respond differently to current telaprevir-based or boceprevir-based triple therapy. This review summarizes the most recent advances in the diagnosis and monitoring of HCV chronic infection.

Development of a nucleic acid lateral flow strip for detection of hepatitis C virus (HCV) core antigen

The object of this study was to develop a simple, rapid, specific, and highly sensitive method to detect HCV core antigen. A nucleic acid aptamer was designed with the high specificity and sensitivity in a nucleic acid lateral flow strip to compete with HCV core antigen and DNA probes. The lower detection limit of the test strip was calculated to be 10 pg/mL with the scanner and 100 pg/mL with naked eyes. Results showed that there were no cross-interactions with other proteins such as HCV NS3, E1/E2 antigens, HIV p24 antigens, or BSA proteins (HCV unrelated protein). When the viral load exceeded 10(4) copies/mL, the positive coincidence rates of ELISA and strip detection, when compared with the HCV RNA assay, were 98.44% and 97.28%, respectively. The results indicated that the ELISA detection and strip assay were in good agreement with the measured value. The results indicated that a nucleic acid lateral flow strip was a simple, rapid, specific, highly sensitive, and cost-effective field-based method for detecting HCV core antigen. The strip assay is an acceptable alternative to diagnose HCV core antigen and to investigate its epidemiology in clinical laboratories lacking specialized equipment and skills.

Hepatitis C virus core antigen assay: can we think beyond convention in resource limited settings?

Hepatitis C virus infects over 15 million patients from India and 2.86 million from Brazil. Detection of anti-hepatitis C virus antibodies has limited sensitivity during acute phase: the pre-seroconversion window period. Hepatitis C virus-RNA detection techniques are used to overcome this shortfall, but are costly and unavailable widely in developing countries. Estimation of hepatitis C virus core-antigen, a protein with highly conserved sequence, by enzyme-immunoassays is an economic and simpler alternative to RNA detection. This study was conducted in Delhi, involving 300 acute and chronic liver disease patients, tested for anti-hepatitis C virus 3rd-generation ELISA, hepatitis C virus core-antigen-ELISA and hepatitis C virus-RNA reverse transcription-polymerase chain reaction. Among the acute patients, hepatitis C virus core-antigen assay could identify 13 out of 14 pre-seroconversion window period cases and 6 out of 8 seroconverted cases, with a pre-seroconversion window period sensitivity of 92.9% and specificity of 100%. In hepatitis C virus core-antigen-positive cases, the viral load was in the range of 4900 to 1.46 × 10⁶ IU/mL, whereas in hepatitis C virus core-antigen-negative cases, the range of viral load was 100–4500 IU/mL. The cost of the hepatitis C virus core-antigen-ELISA was estimated around 3–4 times lesser than the in-house reverse transcription-polymerase chain reaction and 9–10 times lesser than the United States Food and Drug Administration approved reverse transcription-polymerase chain reaction. With a good sensitivity and specificity in the acute phase of infection, hepatitis C virus core-antigen-ELISA can thus be a useful alternative in the developing nations.

Patterns of HCV-RNA and HCV core antigen in the early monitoring of standard treatment for chronic hepatitis C

BACKGROUND

An early drop of HCV-RNA levels is useful in assessing response to antiviral treatment in chronic hepatitis C; the first recommended time point is 4 weeks after the start of therapy.

OBJECTIVES

We evaluated retrospectively HCV-RNA and HCVAg levels at different time points to assess the clinical value of an early monitoring.

STUDY DESIGN

Thirty-five patients with chronic hepatitis C infected by genotype 1b and consecutively enrolled in an open-label study on PegIFN plus Ribavirin and/or ketoprofene were tested for HCV-RNA (real-time PCR) and HCVAg (ARCHITECT) at baseline and after 1 and 2 days and 1, 2, 4 and 12 weeks after the start of treatment. Treatment response was assessed according to the EASL consensus criteria.

RESULTS

In the 17 sustained responders (SR) the median log decrease of HCV-RNA and HCVAg at the different time points was 0.40 and 0.37; 1.36 and 0.84; 1.47 and 0.97; 2.34 and 1.86; 2.51 and 2.32; 3.28 and 2.61, respectively. The best time point to predict SR was 2 weeks after the start of therapy, with a sensitivity, specificity and overall accuracy of 76.9%, 86.7% and 82.1% for HCV-RNA and 81.8%, 75.0% and 76.8% for HCVAg, respectively.

DISCUSSION

An early monitoring is at least equally effective than standard monitoring in predicting response to hepatitis C therapy. The similarity of HCV-RNA and HCVAg kinetics suggests that HCVAg may be useful in the early phases as a trigger to evaluate HCV-RNA levels at earlier time points for a personalized approach to therapy monitoring.