Utility of a commercial quantitative hepatitis C virus core antigen assay in a diagnostic laboratory setting

Diagnostic performance of hepatitis C core antigen assay to identify active infections: A systematic review and meta-analysis

Hepatitis C virus (HCV) core antigen (HCVcAg) assay is an alternative for diagnosing HCV infection in a single step. This meta-analysis aimed to evaluate the Abbott ARCHITECT HCV Ag assay's diagnostic performance (validity and utility) for diagnosing active hepatitis C. PubMed, EMBASE, Scopus, Web of Science, and Cochrane Library were searched until 10 January 2023. The protocol was registered at the prospective international register of systematic reviews (PROSPERO: CRD42022337191). Abbott ARCHITECT HCV Ag assay was the test for evaluation, and nucleic acid amplification tests with a cut-off ≤50 IU/mL were the gold standard. Statistical analysis was performed using STATA with the MIDAS module and random-effects models. The bivariate analysis was conducted on 46 studies (18,116 samples). The pooled sensitivity was 0.96 (95% CI = 0.94-0.97), specificity 0.99 (95% CI = 0.99-1.00), positive likelihood ratio 141.81 (95% CI = 72.39-277.79), and negative likelihood ratio 0.04 (95% CI = 0.03-0.06). The area under the summary receiver operating characteristic curve was 1.00 (95% CI = 0.34-1.00). For active hepatitis C prevalence values of 0.1%-15%, the probability that a positive test was a true positive was 12%-96%, respectively, indicating that a confirmatory test should be necessary, particularly with a prevalence ≤5%. However, the probability that a negative test was a false negative was close to zero, indicating the absence of HCV infection. The validity (accuracy) of the Abbott ARCHITECT HCV Ag assay for screening active HCV infection in serum/plasma samples was excellent. Although the HCVcAg assay showed limited diagnostic utility in low prevalence settings (≤1%), it might help diagnose hepatitis C in high prevalence scenarios (≥5%).

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

Background

The World Health Organization (WHO) aims to achieve global hepatitis C elimination by 2030, defined as diagnosis of 90% of infected individuals and treating 80% of them. Current guidelines for the screening and diagnosis of hepatitis C infection denote using a relatively cheap screen with anti-hepatitis C virus (HCV) antibody immunoassay, followed by the much costlier molecular test for HCV RNA levels using polymerase chain reaction (PCR) assay to confirm active HCV infection. Simplification of the HCV evaluation algorithm to reduce the number of required tests could considerably expand the provision of HCV treatment especially in a developing country. This study investigates the performance of hepatitis C Core Antigen (HCV Ag) test by comparing HCV Ag results versus the results obtained with HCV ribonucleic acid (RNA) PCR which is considered the gold standard for the diagnosis of HCV infection.

Results

Among the 109 anti-HCV positive sera, 96 were positive for both HCV Ag (> 3 fmol/L) and HCV RNA (> 15 IU/mL); 8 were negative for both tests, while the remaining 5 were positive for HCV RNA only. Considering the HCV RNA as gold standard; the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HCV Ag test were found to be 95.05%, 100%, 100%, and 61.54%, respectively. HCV genotype was performed for 59 patients. The most common HCV genotype was genotype 1 (72.9%). Genotype 2 (15.3%) and genotype 3 (11.9%) were detected in the others samples. A high level of correlation was seen between HCV RNA and HCV Ag (r = 0.958, p < 0.001). The correlation for the samples that were genotyped 1 was significant (r = 0.966, p < 0.001).

Conclusion

In our study, it was found that there was strong correlation between HCV RNA levels and HCV Ag levels. So, it can be used for a one-step HCV antigen test to diagnose active HCV infection.

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

PURPOSE

The major bottleneck in most developing countries to attain the WHO goal of eliminating hepatitis C as a public health threat by 2030 is the limited access to molecular testing and loss of infected patients to follow up. Many of the hepatitis C virus (HCV) infected patients fail to get the confirmatory HCV RNA test done after initial screening for anti-HCV antibody. The hepatitis C core antigen (HCVcAg) chemiluminescence-based assay which is newly introduced in the Indian health setup could prove to be a potential marker in the single-point screening and confirmation of HCV infection. This study was done to evaluate the performance of the HCVcAg assay for diagnosis and treatment monitoring of patients with HCV infection.

METHODS

In this retrospective study 208 archived plasma samples from 184 patients were retrieved and all three markers for the laboratory diagnosis of HCV infection, anti-HCV, HCV RNA and HCVcAg were performed in a single freeze thaw cycle. For a subset of patients (n ​= ​24), paired samples, baseline samples and samples collected at 12 weeks after completion of treatment (SVR12) were available.

RESULTS

The sensitivity and specificity of the HCVcAg assay were 91.58% and 99.12% respectively with HCV RNA as the gold standard for the detection of active infection. There was a strong correlation between HCVcAg and HCV RNA (R ​= ​0.85, p ​< ​0•0001). Among the paired samples, the concordance between the HCVcAg and HCV RNA at baseline and at SVR12 was 95.8%.

CONCLUSION

The HCVcAg assay showed a good correlation with the gold standard HCV RNA assay, especially in the case of treatment naïve patients. Thus, the use of HCVcAg assay as tool for testing and confirmation of HCV infection has the potential to increase the uptake of HCV testing.

Hepatitis C core antigen: a simple predictive marker for treatment response to the new direct-acting antiviral drugs in chronic HCV Egyptian patients

Background

Successful eradication of hepatitis C virus (HCV) has great impact on the prognosis of HCV-related complications and the associated mortality. The development of the new direct-acting antiviral drugs (DAAs) has revolutionized the treatment of HCV infection. HCV core antigen (HCVcAg) is a recently developed marker that displayed a good correlation with HCV RNA assays. Our main objectives were to correlate between serum levels of HCVcAg and HCV RNA loads in chronic HCV patients as well as to explore the potential value of HCVcAg assay in predicting treatment response to the new DAAs. The study enrolled a total of 280 chronic HCV-infected patients scheduled to start the new regimen for treatment of chronic HCV by all-oral, interferon-free DAAs. According to the viral load, the studied individuals were arranged into three groups corresponding to mild, moderate, and sever viremia. Serum level of HCVcAg was determined by ELISA technique and HCV RNA viral loads were quantified using the real-time PCR system. The assays were performed three times for all participants: prior to initiation of treatment, at the end of treatment (week 12), and 3 months post-treatment cessation (week 24).

Results

A statistically significant difference between HCV RNA and HCVcAg baseline levels among different viremia groups was detected (P < 0.001). There was a significant positive correlation between HCV RNA and HCVcAg baseline values among all the studied cases (P < 0.05) with a correlation coefficient of 0.752, 0.976, and 1.00 respectively for mild, moderate, and severe viremia groups. 92.9% (260/280) of the studied patients achieved sustained virologic response, 3.6% (10/280) were non-responders, and 3.6% (10/280) had recurrent viremia/relapse as regards RT-PCR results.

Conclusion

HCVcAg is a promising alternative to HCV RNA assay. The ELISAs for HCVcAg proved excellent correlations with HCV RNA levels. Moreover, HCVcAg can be introduced as a simple and highly specific tool for monitoring the new DAA regimens particularly in low-resource settings.

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

INTRODUCTION:

We compared the hepatitis C virus (HCV) core antigen test with the HCV RNA assay to confirm anti-HCV results to determine whether the HCV core antigen test could be used as an alternative confirmatory test to the HCV RNA test.

METHODS:

Sera from 156 patients were analyzed for anti-HCV and HCV core antigen using a chemiluminescent microparticle immunoassay (Architect i2000SR) and for HCV RNA using the artus HCV RG RT-PCR Kit (QIAGEN) in a Rotor-Gene Q instrument.

RESULTS:

The diagnostic sensitivity, specificity, and positive and negative predictive values of the HCV core antigen assay compared to the HCV RNA test were 77.35%, 100%, 100%, and 89.38%, respectively. HCV core antigen levels showed a good correlation with those from HCV RNA quantification (r =0.872). However, 13 samples with a viral load of less than 4000 IU/mL were negative in the HCV core antigen assay. All gray-zone reactive samples were also RNA positive and were positive on repeat testing.

CONCLUSIONS:

The Architect HCV core antigen assay is highly specific and has an excellent positive predictive value. At the present level of sensitivity (77%), the study is still relevant in a low-income setting in which most of the HCV-positive patients would go undiagnosed, since HCV RNA testing is not available and/or not affordable. HCV core antigen testing can also help determine the true burden of infection in a population, considering the fact that almost 50% of the anti-HCV positive cases are negative for HCV RNA.

Routine screening for hepatitis C viral infection in patients undergoing elective cranial neurosurgery

OBJECTIVE

Undiagnosed hepatitis C virus (HCV) and HIV in patients present risks of transmission of bloodborne infections to surgeons intraoperatively. Presurgical screening has been suggested as a protocol to protect surgical staff from these pathogens. The authors sought to determine the incidence of HCV and HIV infection in elective craniotomy patients and analyze the cost-effectiveness of universal and risk factor-specific screening for protection of the surgical staff.

METHODS

All patients undergoing elective craniotomy between July 2009 and July 2016 at the National Brain Aneurysm Center who did not refuse screening were included in this study. The authors utilized rapid HCV and HIV tests to screen patients prior to elective surgery, and for each patient who tested positive using the rapid HCV or HIV test, qualitative nucleic acid testing was used to confirm active viral load, and risk factor information was collected. Patients scheduled for nonurgent surgery who were found to be HCV positive were referred to a hepatologist for preoperative treatment. The authors compared risk factors between patients who tested positive on rapid tests, patients with active viral loads, and a random sample of patients who tested negative. The authors also tracked the clinical and material costs of HCV and HIV rapid test screening per patient for cost-effectiveness analysis and calculated the cost per positive result of screening all patients and of screening based on all patient risk factors that differed significantly between patients with and those without positive HCV test results.

RESULTS

The study population of patients scheduled for elective craniotomy included 1461 patients, of whom 22 (1.5%) refused the screening. Of the 1439 patients screened, 15 (1.0%) tested positive for HCV using rapid HCV screening; 9 (60%) of these patients had active viral loads. No patient (0%) tested positive for HIV. Seven (77.8%) of the 9 patients with active viral loads underwent treatment with a hepatologist and were referred back for surgery 3-6 months after sustained virologic response to treatment, but the remaining 2 patients (22.2%) required urgent surgery. Of the 9 patients with active viral loads, 1 patient (11%) had a history of both intravenous drug abuse and tattoos. Two of the 9 patients (22%) had tattoos, and 3 (33%) were born within the age-screening bracket (born 1945-1965) recommended by the Centers for Disease Control and Prevention. Rates of smoking differed significantly (p < 0.001) between patients who had active viral loads of HCV and patients who were HCV negative, and rates of smoking (p < 0.001) and IV drug abuse (p < 0.01) differed significantly between patients who were HCV rapid-test positive and those who were HCV negative. Total screening costs (95% CI) per positive result were $3,877.33 ($2,348.05-$11,119.28) for all patients undergoing HCV rapid screening, $226.29 ($93.54-$312.68) for patients with a history of smoking, and $72.00 ($29.15-$619.39) for patients with a history of IV drug abuse.

CONCLUSIONS

The rate of undiagnosed HCV infection in this patient population was commensurate with national levels. While the cost of universal screening was considerable, screening patients based on a history of smoking or IV drug abuse would likely reduce costs per positive result greatly and potentially provide cost-effective identification and treatment of HCV patients and surgical staff protection. HIV screening found no infected patients and was not cost-effective.

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 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.

Who to test and how to test for chronic hepatitis C infection - 2016 WHO testing guidance for low- and middle-income countries

Testing and diagnosis of hepatitis C virus (HCV) infection is the gateway for access to both treatment and prevention services, and crucial for an effective hepatitis epidemic response. In contrast to HIV, a systematic approach to hepatitis C testing has been fragmented and limited to a few countries, and there remains a large burden of undiagnosed cases globally. Key challenges in the current hepatitis testing response, include lack of simple, reliable, and low cost diagnostic tests, laboratory capacity, and testing facilities; inadequate data to guide country-specific hepatitis testing approaches and who to test; stigmatization and social marginalization of some groups with or at risk of viral hepatitis; and lack of international or national guidelines on hepatitis testing for resource-limited settings. New tools to support the hepatitis global response include the 2016 Global Hepatitis Health Sector Strategy which include targets for testing and diagnosis, and World Health Organization (WHO) 2016 hepatitis testing guidelines for adults, adolescents, and children in low- and middle-income countries. The testing guidance complements recent published WHO guidance on the prevention, care and treatment of chronic hepatitis C and hepatitis B infection. These testing guidelines outline the public health approach to strengthening and expanding current testing practices for HCV and HBV and address what serological and virological assays to use, and who to test, as well as interventions to promote linkage to prevention and care after testing. They are intended for use across all age groups and populations. See boxes for key recommendations. Future directions and innovations in viral hepatitis testing include use of point-of-care assays for nucleic acid testing (NAT) and core antigen; validation of dried blood spots specimens with different commercial serological and NAT assays; multiplex and polyvalent platforms for integrated testing of HIV, HBV and HCV; and potential for self-testing.

Hepatitis C Core Antigen Testing for Diagnosis of Hepatitis C Virus Infection: A Systematic Review and Meta-analysis

BACKGROUND

Diagnosis of chronic hepatitis C virus (HCV) infection requires both a positive HCV antibody screen and confirmatory nucleic acid testing (NAT). Testing for hepatitis C virus core antigen (HCVcAg) is a potential alternative to NAT.

PURPOSE

To evaluate the accuracy of diagnosis of active HCV infection among adults and children for 5 HCVcAg tests compared with NAT.

DATA SOURCES

EMBASE, PubMed, Web of Science, Scopus, and Cochrane Database of Systematic Reviews from 1990 through 31 March 2016.

STUDY SELECTION

Case-control, cross-sectional, cohort, or randomized trials that compared any of 5 HCVcAg tests with an NAT reference standard.

DATA EXTRACTION

2 independent reviewers extracted data and assessed quality using an adapted QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool.

DATA SYNTHESIS

44 studies evaluated 5 index tests. Studies for the Abbott ARCHITECT HCV Ag assay had the highest quality, whereas those for the Ortho HCV Ag enzyme-linked immunosorbent assay (ELISA) had the lowest quality. From bivariate analyses, the sensitivity and specificity of the assays were as follows: Abbott ARCHITECT, 93.4% (95% CI, 90.1% to 96.4%) and 98.8% (CI, 97.4% to 99.5%); Ortho ELISA, 93.2% (CI, 81.6% to 97.7%) and 99.2% (CI, 87.9% to 100%); and Hunan Jynda Bioengineering Group HCV Ag ELISA, 59.5% (CI, 46.0% to 71.7%) and 82.9% (CI, 58.6% to 94.3%). Insufficient data were available for a meta-analysis about the Fujirebio Lumipulse Ortho HCV Ag and Eiken Lumispot HCV Ag assays. In 3 quantitative studies using Abbott ARCHITECT, HCVcAg correlated closely with HCV RNA levels greater than 3000 IU/mL.

LIMITATIONS

Insufficient data were available on covariates, such as HIV or hepatitis B virus status, for subgroup analyses. Few studies reported genotypes of isolates, and data for genotypes 4, 5, and 6 were scant. Most studies were conducted in high-resource settings and reference laboratories.

CONCLUSION

The HCVcAg assays with signal amplification have high sensitivity, high specificity, and good correlation with HCV RNA levels greater than 3000 IU/mL and have the potential to replace NAT in settings with high HCV prevalence.

PRIMARY FUNDING SOURCE

National Institutes of Health.

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.

HCV core antigen and HCV-RNA in HIV/HCV co-infected patients with different HCV genotypes

Background

A good correlation between HCV core antigen (HCVAg) and different HCV-RNA assays has been described, but little data are available in HCV/HIV co-infection. We aimed to evaluate HCVAg in comparison with HCV-RNA and to determine their kinetics during antiviral treatment in selected HCV/HIV co-infected patients.

Methods

355 samples from 286 HCV/HIV co-infected subjects for whom HCV-RNA (Abbott RealTime) was requested were analysed also for HCVAg (Abbott ARCHITECT) in order to evaluate the correlation between the two parameters both in patients treated or untreated for chronic hepatitis C and according to different HCV genotypes. The differences between percentages were evaluated by chi square or Fisher’s exact test, while mean and median values were compared by Student’s t test or the Mann–Whitney test, respectively. All differences were considered significant for a p value <0.05.

Results

HCVAg was detectable on 288/315 sera (91.4%) positive for HCV-RNA and in 5 out of40 (12.5%) sera with undetectable HCV-RNA for a total concordance of 90.1%. The correlation was fair both in untreated (r = 0.742) and in treated (r = 0.881) patients and stronger for genotypes 1 and 4 than for genotype 3. Both HCV-RNA and HCVAg levels were significantly higher (p = 0.028 and p = 0.0098, respectively) in patients infected by genotype 1 than by genotype 3. The mean ratio of Log values between HCV-RNA (IU/mL) and HCVAg (fmol/liter) was 2.27 ± 1.09 in untreated and 2.20 ± 0.82 in treated patients (p = n.s.),consistent with a sensitivity of HCVAg corresponding to about 1,000 IU/mL of HCV-RNA, and ranged from 2.21 to 2.32 among HCV genotypes with no significant differences; five samples (1.4%; 2 genotype 1a or 1c, 3 genotype 3a) showed highly divergent values. The analysis of 18 monitoring profiles from patients treated with PEG-IFN and Ribavirin showed similar trends, except in one case in which relapse could be predicted by HCVAg and not by HCV-RNA.

Conclusion

These results suggest that HCVAg represents an adequate tool for determining an ongoing HCV infection also in HIV co-infected patients, with lower costs and faster turnaround time than HCV-RNA.

MultisHRP-DNA-coated CMWNTs as signal labels for an ultrasensitive hepatitis C virus core antigen electrochemical immunosensor

An ultrasensitive and selective electrochemical immunosensor was developed for the detection of hepatitis C virus (HCV) core antigen. The immunosensor consists of graphitized mesoporous carbon-methylene blue (GMCs-MB) nanocomposite as an electrode modified material and a horseradish peroxidase-DNA-coated carboxyl multi-wall carbon nanotubes (CMWNTs) as a secondary antibody layer. After modification of the electrode with GMCs-MB nanocomposite, Au nanoparticles were electrodeposited on to the electrode to immobilize the captured antibodies. The bridging probe and secondary antibodies linked to the CMWNTs, and DNA concatamers were obtained by hybridization of the biotin-tagged signal and auxiliary probes. Finally, streptavidin-horseradish peroxidases (HRP) were labeled on the secondary antibody layer via biotin-streptavidin system. The reduction current of MB were generated in the presence of hydrogen peroxide and monitored by square wave voltammetry. Under optimum conditions, the amperometric signal increased linearly with the core antigen concentration (0.25pgmL(-1) to 300pgmL(-1)). The immunosensor exhibites the detection limit as low as 0.01pgmL(-1) and it has a high selectivity. The new protocol showed acceptable stability and reproducibility, as well as favorable recovery for HCV core antigen in human serum. The proposed immunosensor has great potential for clinical applications.

APASL consensus statements and management algorithms for hepatitis C virus infection

The Asian Pacific Association for the Study of the Liver (APASL) convened an international working party on the "APASL Consensus Statements and Management Algorithms for Hepatitis C Virus Infection" in December, 2010, in order to revise "Asian Pacific Association for the Study of the Liver consensus statements on the diagnosis, management and treatment of hepatitis C virus infection (J Gastroenterol Hepatol 22:615-633, 2007)". The working party consisted of expert hepatologists from the Asian-Pacific region gathered at Makuhari, Chiba, Japan on 19 December 2010. New data were presented, discussed and debated to draft a revision. Participants of the consensus meeting assessed the quality of cited studies. Finalized recommendations are presented in this review.

Characterization and application of monoclonal antibody against hepatitis C virus nonstructual protein three

Developing assays for detecting HCV antigens could be beneficial because viral proteins appear earlier than antibodies and are more stable than RNA in the serum. Monoclonal antibody was prepared by immunization and cell fusion. Subclass, specificity, and efficiency of monoclonal antibodies were determined by ELISA. Epitope specificity of monoclonal antibodies was analyzed by ELISA additivity test. HCV antigen in serum of hepatitis patients was examined by double monoclonal antibody sandwich ELISA. Five hybridoma cell lines were screened and named HCV(1), HCV(2), HCV(3), HCV(4), and HCV(5). These five monoclonal antibodies had high specificity and efficiency. The additivity test showed that HCV(2), HCV(4), and HCV(5) recognized different epitopes, which can be matched in ELISA. Of 173 anti-HCV positive patients, 37 (21.4%) were positive for HCV antigen. Of 1498 anti-HCV negative patients, 10 (0.67%) were positive for HCV antigen. Fifty normal controls were negative for HCV antigen. HCV antigen detection had moderate agreement and correlation with HCV RNA detection (kappa=0.577, p<0.01; r=0.59, p<0.01). This result indicates that the monoclonal antibody against HCV NS(3) may be a potential diagnostic reagent, which would provide a foundation for developing a sandwich ELISA of HCV antigen detection.