Is hepatitis C virus core antigen an adequate marker for community screening? J Clin Microbiol. 2012;50:1989-1993. [PMID: 22461676 DOI: 10.1128/jcm.05175-11]

Hepatitis C Virus-Core Antigen: Implications in Diagnostic, Treatment Monitoring and Clinical Outcomes

The hepatitis C virus (HCV) infection, a global health concern, can lead to chronic liver disease. The HCV core antigen (HCVcAg), a viral protein essential for replication, offers a cost-effective alternative to HCV RNA testing, particularly in resource-limited settings. This review explores the significance of HCVcAg, a key protein in the hepatitis C virus, examining its structure, function, and role in the viral life cycle. It also evaluates its clinical use in diagnosis and treatment monitoring, comparing its performance to the standard HCV RNA assay using data from PubMed and Google Scholar. HCVcAg assays show high pooled sensitivity (93.5%) and pooled specificity (99.2%) compared to HCV RNA assays, correlating closely (r = 0.87) with HCV RNA levels. Hence, HCVcAg testing offers a cost-effective way to diagnose active HCV infections and monitor treatment, especially in resource-limited settings, but its sensitivity can vary and standardization is needed. HCVcAg also predicts liver disease progression and assesses liver damage risk, aiding patient management. It helps to identify patients at risk for fibrosis or carcinoma, making it vital in hepatitis C care. HCVcAg testing can expand access to HCV care, simplify management, and contribute to global elimination strategies, especially in low- and middle-income countries.

Hepatitis C virus core antigen: A diagnostic and treatment monitoring marker of hepatitis C virus in Indian population

BACKGROUND

The diagnosis and treatment monitoring of hepatitis C is quite challenging. The screening test, i.e. antibody assay, is unable to detect acute cases, while the gold standard hepatitis C virus (HCV) reverse transcriptase polymerase chain reaction (RTPCR) assay is not feasible in resource-limited countries such as India due to high cost and infrastructure requirement. European Association for the Study of the Liver and World Health Organization have approved a new marker, i.e. HCV core antigen (HCVcAg) assay, as an alternative to molecular assay. In this study, we have evaluated HCVcAg assay for diagnosis and treatment monitoring follow-up in Indian population infected with hepatitis C.

METHODS

Blood specimen of 90 clinically suspected cases of acute hepatitis C were tested simultaneously for anti-HCV antibody assay via ELISA (enzyme-linked immunoassay), HCVcAg assay by chemiluminescence immune assay (CLIA) and HCV RTPCR VL (viral load) assay. Thirty-four HCV RTPCR positive patients were further enrolled in treatment monitoring group whose blood samples were tested at the beginning of treatment, two weeks, four weeks and 12 weeks via HCV core Ag assay and HCV RTPCR Viral Load assay.

RESULTS

Considering HCV RTPCR as gold standard, diagnostic performance of HCV core Ag assay and anti-HCV antibody assay was evaluated. The sensitivity and specificity of HCV core Ag assay were higher than that of anti-HCV Antibody assay, i.e. 88.3% and 100% vs. 23.3% and 83.3%, respectively. The overall diagnostic accuracy of HCV core Ag assay was 92.20%. Among treatment follow-up group, HCV core Ag levels correlated well with HCV viral load levels, at the beginning of treatment (baseline) till 12 weeks showing highly significant Spearman rank correlation coefficient of > 0.9 with HCV viral load levels.

CONCLUSIONS

HCV core Ag assay is a cost-effective, practically feasible substitute of HCV RTPCR viral load assay for diagnosis as well as long duration treatment monitoring of hepatitis C infection in resource-limited settings.

Clinicoepidemiology and Diagnosis of Hepatitis C: Evaluating HCV Core Antigen Assay as a Diagnostic Tool in a Tertiary Care Teaching Hospital of North India

Introduction

One of the main causes of primary hepatocellular carcinoma and chronic hepatitis is the hepatitis C virus (HCV), with significant variability in its genotypes affecting pathogenicity and treatment outcomes. In India, prevalence ranges from 0.5 to 1.5%, with certain regions showing higher rates. Diagnostic methods include serological and molecular assays, with the HCV core antigen (HCV cAg) assay emerging as a cost-effective substitute for HCV RT-PCR testing.

Materials and methods

This study enrolled 292 suspected hepatitis cases from May 2019 to May 2020 in a North Indian tertiary care institute. Demographic, biochemical, and clinical data were collected. Seroprevalence was determined using QualisaTM HCV ELISA. Sixty seronegative and 30 seropositive samples underwent HCVc-Ag testing and HCV RT-PCR. Genotyping was carried out using AmpliSens® HCV-genotype PCR kit. The HCV core antigen assay was evaluated by taking HCV RT-PCR as the gold standard test.

Results

Of the 292 patients, 98 (30%) were seropositive for HCV, predominantly in the 40-59 age-group. Surgery and blood transfusion were significant risk factors. Co-infections included human immunodeficiency virus (HIV) (3.06%) and hepatitis B virus (HBV) (6.12%). Genotype 3a was the most prevalent. HCV core antigen assay showed 93.75% sensitivity, 93.10% specificity, 88.24% positive predictive value, 96.43% negative predictive value, and 93.33% accuracy.

Conclusion

Hepatitis C virus core antigen is a dependable and economical substitute to HCV RT-PCR for diagnosing HCV infection. Regular screening in high-risk groups is essential for early detection and prevention.

How to cite this article

Rautela A, Raj N, Verma A, et al. Clinicoepidemiology and Diagnosis of Hepatitis C: Evaluating HCV Core Antigen Assay as a Diagnostic Tool in a Tertiary Care Teaching Hospital of North India. Euroasian J Hepato-Gastroenterol 2024;14(2):176-181.

Community-based screening by Anti-HCV reflex HCV Ag test and accessible post-screening care toward elimination of hepatitis C in two hyperendemic townships

BACKGROUND

Hyperendemic townships of hepatitis C virus (HCV) infection should devote extra efforts to eliminate HCV. We aimed to evaluate efficacy of the screening and linkage to care in two HCV hyperendemic townships.

METHODS

Village-to-village HCV screening using anti-HCV reflex HCV Ag test was conducted in two HCV hyperendemic rural townships (Lioujiao and Yijhu). All residents aged 30 years or older were invited. Those patients detected as infected were referred to nearby hospitals or clinics in Lioujiao and to an accessible outreach hepatology clinic in Yijhu.

RESULTS

The populations of Lioujiao and Yijhu townships at time of survey were 18,389 and 14,787 with 6086 (33.1%) and 4604 (31.1%) having ever been previously screened, and 1517 and 1071 responded to this screening respectively. Their crude screening coverage rates were 41.5% and 38.5%, and adjusted screening coverage rates were 54.3% and 94.6% respectively. The prevalence rates of anti-HCV and HCV Ag were 17.9% and 11.9% in Lioujiao, and 9.2% and 5.6% in Yijhu respectively, with their rates of antigenemia (HCV Ag/anti-HCV) being 62.1% and 60.6% respectively. Numbers needed to test (NNT) to find a candidate for anti-viral treatment were 9 and 18. For linkage to care, treatment rate by referral (Lioujiao) was slightly lower than by accessible outreach hepatology clinic (Yijhu) (84.9% vs. 93.3%, p = 0.093). Overall successful sustained virological response rate at week 12 was 98.2% (161/164) in outreach hepatology clinic.

CONCLUSION

Since NNT was low, it was worthwhile conducting intensive screening in these hyperendemic townships. For high treatment rate, accessible outreach hepatology clinic is feasible especially in areas without adequate medical resources.

Community-Based Screening for Hepatitis B and C Infectivity Using Two Quantitative Antigens to Identify Endemic Townships

Screening and linkage to care are essential to achieve viral hepatitis elimination before 2030. The accurate identification of endemic areas is important for controlling diseases with geographic aggregation. Viral activity drives prognosis of chronic hepatitis B and hepatitis C virus infection. This screening was conducted in Chiayi County from 2018–2019. All residents aged 30 years or older were invited to participate in quantitative HBsAg (qHBsAg) and HCV Ag screening. Among the 4010 participants (male:female = 1630:2380), the prevalence of qHBsAg and HCV Ag was 9.9% (396/4010) and 4.1% (163/4010), respectively. High-prevalence townships were identified, three for qHBsAg > 15% and two for HCV Ag > 10%. The age-specific prevalence of qHBsAg was distributed in an inverse U-shape with a peak (16.0%, 68/424) for subjects in their 40 s; for HCV, prevalence increased with age. Concentrations of qHBsAg < 200 IU/mL were found in 54% (214/396) of carriers. The rate of oral antiviral treatment for HCV was 75.5% (114/151), with subjects younger than 75 years tending to undergo treatment (85.6% vs. 57.4%, p < 0.001). QHBsAg and HCV Ag core antigens can reflect the concentration of the viral load, which serves as a feasible screening tool. Using quantitative antigen screening for hepatitis B and C in community-based screening, two hyperendemic townships were identified from an endemic county.

Prevalence, diagnosis, and treatment of hepatitis C in Mainland China

Infection with the hepatitis C virus (HCV) is a major cause of liver disease and hepatocellular carcinoma in China. Rapid economic development has had an enormous impact on the epidemiology and treatment of hepatitis C. The prevalence of anti-HCV antibodies in Mainland China is approximately 0.91%, and use of injected drugs has become the main route of HCV transmission in China. Reimbursement for 3 direct-acting antivirals (DAAs) has been approved by the National Medical Insurance scheme in China, which ensures the accessibility of treatment for an HCV infection. To improve the awareness of treatments for hepatitis C among medical personnel and the rate of in-hospital screening for HCV, the Chinese Medical Association has formulated guidelines for the diagnosis and treatment of hepatitis C and a process of in-hospital screening for hepatitis C in China. These efforts have standardized the screening, diagnosis, treatment, and management of hepatitis C. Based on the international strategy for micro-elimination of hepatitis C, China has also screened and treated groups at risk of hepatitis C infection, and this has reduced the number of the infected. The current review describes the status of and issues with the prevalence, diagnosis, and treatment of hepatitis C in Mainland China as part of the global effort to eliminate viral hepatitis by 2030.

Village-to-village screening for hepatitis B and C using quantitative HBsAg and anti-HCV testing with reflex HCV core antigen tests in the remote communities of a resource-rich setting: a population-based prospective cohort study

OBJECTIVES

Community-based screening for hepatitis B virus (HBV) and hepatitis C virus (HCV) is essential for hepatitis elimination. This study attempted to increase screening accessibility and efficacy by using alternative tools.

DESIGN

Population-based prospective cohort study.

SETTING

Hepatitis elimination program at Yunlin County, Taiwan.

PARTICIPANTS

All 4552 individuals participated in 60 screening sessions of a community-based HBV and HCV screening project in five rural townships with approximately 95 000 inhabitants in central-western Taiwan.

INTERVENTIONS

To increase accessibility, 60 outreach screening sessions were conducted in 41 disseminative sites. Quantitative HBV surface antigen (qHBsAg) and anti-HCV testing with reflex HCV core antigen (HCV Ag) tests were employed as alternative screening tools.

MAIN OUTCOME MEASURES

Calculate village-specific prevalence of HBsAg, anti-HCV and HCV Ag and establish patient allocation strategies according to levels of qHBsAg HCV Ag and alanine aminotransferase (ALT).

RESULTS

Of 4552 participants, 553, 697 and 290 were positive for HBsAg, anti-HCV and HCV Ag, respectively; 75 of them had both HBsAg and anti-HCV positivity. The average (range) number of participants in each screening session was 98 (31-150). The prevalence rates (range) of HBsAg, anti-HCV and HCV Ag were 12.1% (4.3%-19.4%), 15.3% (2.6%-52.3%) and 6.4% (0%-30.2%), respectively. The HCV Ag positivity rate among anti-HCV-positive participants was 42% (0%-100%). Using cut-off values of >200 IU/mL for qHBsAg, >3 fmol/L for HCV Ag and >40 IU/mL for ALT as criteria for patient referral, we noted an 80.2% reduction in referral burden. Three villages had high anti-HCV prevalences of 52.3%, 53.8% and 63.4% with corresponding viraemic prevalences of 23.2%, 30.1% and 22% and thus constituted newly identified HCV-hyperendemic villages.

CONCLUSION

Outreach hepatitis screening increases accessibility for residents in rural communities. Screening HBV and HCV through qHBsAg and HCV Ag tests provides information concerning viral activities, which might be conducive to precise patient allocation in remote communities.

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.

Hepatitis C virus core antigen as alternative diagnostic algorithm for active hepatitis C virus infection among haemodialysis population: Cost implications

AIMS

In Malaysia, majority anti-HCV positive haemodialysis patients do not undergo hepatitis C confirmation due to the high cost of HCV RNA. HCV Core Antigen might be a cost-effective diagnostic test to identify HD patients who have active HCV infection eligible for Direct Acting Anti-viral therapy.

METHODS

A cross-sectional study was conducted to assess the correlation between HCV Ag and HCV RNA and the cost implications of different diagnostic algorithms to diagnose active HCV infection using Anti-HCV, HCV Ag, and HCV RNA. Pre-dialysis blood was tested for both HCV Ag and HCV RNA. HCV Ag was tested with Abbott ARCHITECT HCV Ag test.

RESULTS

Two-hundred twenty-seven haemodialysis patients were recruited from 20 centres with mean age of 57.68 ± 12.48 years, and male constitutes 56.8% (129) of the study population. HCV Ag correlated well with HCV RNA (Spearman test coefficient 0.943, p < .001) with sensitivity of 93.9%, specificity 99.3%, and the accuracy was 97.36%. Cost analysis indicated that a sequential test involving Anti-HCV antibody as initial screening, followed by HCV Ag on Anti-HCV positive and HCV RNA on HCV Ag negative cases translated to a modest cost-saving algorithm compared to standard diagnostic algorithm.

CONCLUSION

HCV Ag correlated well with HCV RNA and can potentially be fused in an alternative diagnostic algorithm to generate cost savings methods to diagnose active HCV infection among haemodialysis patients. This alternative algorithm is especially relevant in low to middle-income countries such as Malaysia to optimize the use of the healthcare resource and gains in clinical outcomes.

Feasibility of anti-HCV reflex HCV Ag screening strategy in an HCV endemic community

BACKGROUND/PURPOSE

The HCV core antigen (HCV Ag) assay displays high sensitivity and strong correlation with HCV RNA. However, the feasibility of anti-HCV reflex HCV Ag screening in a community-wide setting is rarely discussed.

METHODS

We performed a two-phase community-based hepatitis C screen in an HCV-prone area of central Taiwan. During the training phase, all participants were test for anti-HCV, HCV Ag and HCV RNA to validate sensitivity, specificity, and accuracy of HCV Ag. During the validation phase, an anti-HCV reflex HCV Ag screen was conducted based on the results of training phase. Outcomes of the study were presented as positive and negative predictive values (PPV and NPV).

RESULTS

Of 935 training phase participants, the rate of positive anti-HCV and HCV Ag were 175 (18.7%) and 78 (8.3%), respectively. Test sensitivity, specificity, and accuracy of HCV Ag were 97.1%, 98.6%, and 97.8%, respectively. During validation phase, only anti-HCV-positive serum samples were tested for HCV Ag. Of 1932 participant, 285 (14.8%) were anti-HCV-positive. 133 (46.7%) of the 285 anti-HCV-positive samples were HCV Ag-positive. PPV and NPV were 98.4% and 99.3%, respectively. Across the entire participant sample, a significant linear correlation between HCV Ag and HCV RNA concentration was noted (r² = 0.93, p-value<0.001) following log-log transformation.

CONCLUSION

Anti-HCV reflex HCV Ag screening is a feasible strategy for aiding HCV-prone communities.

Correlation analysis of hepatitis C virus core antigen and low viral loads: Can core antigen replace nucleic acid test?

Value of hepatitis C virus (HCV) core antigen (cAg) test has been controversy in patients with low HCV loads for its lower sensitivity. We assessed correlation between HCV-cAg and HCV RNA in serum samples with low viral loads and analyzed the performance of HCV-cAg assay in determining diagnosis and treatment outcomes in chronic hepatitis C patients. Both HCV RNA and HCV-cAg were detected for 2298 serum samples. Correlation analysis was performed between the two tests. Receiver operating characteristics (ROC) curve was used to assess value of HCV-cAg test in determining diagnosis and response outcomes at the different HCV RNA thresholds. The two tests were correlated very well, and moreover, correlation in the low viral load group was higher than that in the high viral load group (r value: 0.901 and 0.517). Positive agreement of HCV-cAg ≥ 3 fmol/L was as high as 97.0% for HCV RNA ≥ 1000 IU/mL, and its negative agreement for HCV RNA < 15 IU/mL was up to 98.9% in all samples. Area under ROCs ranged from 0.939 to 0.992, regardless of HCV RNA thresholds. When lower limit of detection of HCV RNA was 15, 100 or 1000 IU/mL, positive predictive value of HCV-cAg was 96.8%, 98.8% or 92.4%, and its negative predictive value was 87.0%, 89.9% or 98.3%, respectively, on the basis of different cutoff values. High-sensitivity HCV-cAg detection may likely replace HCV RNA to confirm the existence of HCV and to guide the treatment of chronic HCV infection.

Residual hepatitis C virus in peripheral blood mononuclear cell as a risk factor for hepatocellular carcinoma after achieving a sustained virological response: a dogma or fiction

BACKGROUND

Clinical worsening after achieving a sustained virological response (SVR) needs to be clarified and explained. Persistence of hepatitis C virus (HCV) core antigen interacts with the host proteins to interfere with signaling pathways and increases the susceptibility to hepatic carcinogenesis.

OBJECTIVE

This study aimed to investigate the risk factors that increase the progression of liver disease and hepatocellular carcinoma in a subgroup of HCV patients who achieved a SVR.

PATIENTS AND METHODS

Eighty-nine HCV patients with hepatic decompensation were selected 8.2 ± 1.8 months after achieving SVR24. HCV core antigen and HCV RNA were detected in peripheral blood mononuclear cells. Matched control (n = 100) and training (n = 200) groups were recruited.

RESULTS

Eighty-five patients showed a progression of Child-Turcotte-Pugh and model for end-stage liver disease scores, with positive RNA in peripheral blood mononuclear cell (357.4 ± 42.1 IU/million cell) and positive hepatitis C virus core antigen (n = 73); four patients were excluded. Susceptibility to decompensation and hepatocellular carcinoma after direct-acting antiviral drugs increased with age [odds ratio (OD) = 1.87], and was associated with male sex (OD = 1.65), diabetes (OD = 3.68), thrombocytopenia (OD = 2.44), pretreatment Alfa-fetoprotein (OD = 3.41), and occult HCV (OD = 4.1).

CONCLUSION

Clinical deterioration after SVR could be explained by occult HCV mainly in older male patients with diabetes and thrombocytopenia.

Developments in the HCV Screening Technologies Based on the Detection of Antigens and Antibodies

Hepatitis C virus (HCV) accounts for 15%-20% of cases of acute infection, and chronic HCV infection is developed in about 50%-80% of HCV patients. Unfortunately, due to the lack of proper medical care, difficulty in screening for HCV infection, and lack of awareness resulted in chronic HCV infection in 71 million people on a global scale, and about 399,000 deaths in 2016. It is crucial to recognize that the effective use of antiviral medicines can cure more than 95% of HCV infected people. The Global Health Sector Strategy (GHSS) aim is to reduce the new HCV infections and the HCV associated mortality by 90% and 65%, respectively. Therefore, the methods that are simple, yet powerful enough to detect HCV infections with high sensitivity, specificity, and a shorter window period are crucial to restrain the global burden of HCV healthcare. This article focuses on the technologies used for the detection of HCV in clinical specimens.

Community screening for hepatitis C virus infection in a low-prevalence population

BACKGROUND

Age cohort screening for hepatitis C virus (HCV) might be an effective strategy if the majority of undiagnosed cases are concentrated in a particular age group. The objective of this study was to determine HCV prevalence in different age cohorts of the general population in the Central European part of Russia and second, to assess feasibility of HCV antigen testing for community screening programs.

METHODS

Sera from 2027 volunteers were tested for anti-HCV (Architect Anti-HCV, Abbott Laboratories). All anti-HCV reactive samples were confirmed in an immunoblot and tested for HCV Ag (ARCHITECT HCV Ag, Abbott Laboratories), HCV RNA and HCV viral load.

RESULTS

Out of 31 individuals with anti-HCV reactive result, 22 (71%) were confirmed by immunoblot, six were false positives and three were indeterminate. Active infection was observed in 73% of anti-HCV confirmed positives. Five out of 16 individuals had low HCV-RNA levels (< 10,000 IU/mL) and one of those had a very low level (594 IU/mL). Agreement between HCV Ag and HCV RNA was 100%. Total anti-HCV and active HCV infection rates were 1.09% (22/2027) and 0.79% (16/2027), respectively. The peak rates were observed in people 60 years or older (anti-HCV: 2.84% [95% CI: 1.66-4.74%], 13/319; HCV RNA/HCV Ag: 2.23% [95% CI: 1.20-4.00%], 10/319).

CONCLUSIONS

Overall HCV prevalence is low, except in people 60 years or older. The latter should be considered as a target group for HCV screening. The high agreement between HCV RNA and HCV Ag suggests the utility of HCV Ag testing to confirm active infection in screening programs.

Hepatitis C virus core antigen is cost-effective in community-based screening of active hepatitis C infection in Taiwan

BACKGROUND AND PURPOSE

Hepatitis C virus (HCV) core antigen is highly sensitive and specific in viremic HCV diagnosis. This study evaluated the cost-effectiveness of HCV core antigen (HCVcAg) in community-based screening for active HCV infection.

METHODS

Between 2017/07 and 2018/07, community-based screenings for active HCV infection with two-step (anti-HCV for screening and HCVRNA for diagnosis) and one-step processes (HCVcAg for screening and diagnosis) were conducted in two districts in Kaohsiung City. While HCVcAg test was positive at ≥3 fmol/L, the lowest level of HCV-RNA detection was 12 IU/mL. We analyzed the cost-effectiveness of two algorithms in identifying active HCV infection.

RESULTS

There were two large-scale screenings using the two-step process with a total of 2452 residents enrolled; while six hundred and forty-four residents participated in continuous small-scale screening with the one-step process. The prevalence of anti-HCV and positive HCVcAg was 3.4% and 2.8%. The viremic rate was 1.4% and 2.8% for two- and one-step processes (p < 0.001). While all positive HCVcAg were viremic, 42.4% of positive anti-HCV patients had viremia. The positive predictive value was 42.2% and 100% for two- and one-step processes in detecting active HCV infection (p < 0.001). In identifying one active HCV infection, the cost was $755.3 and $711.1 dollars for two- and one-step processes respectively.

CONCLUSION

Compared to the two-step process in community-based screening, continuous screening with the HCVcAg test as a one-step tool for active HCV infection was cost-effective in areas with low seroprevalence of HCV in Taiwan.

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.

HCV core antigen comes of age: a new opportunity for the diagnosis of hepatitis C virus infection

The diagnosis of hepatitis C virus (HCV) infection has been traditionally based on the detection of the host antibody response. Although antibody assays are available in different formats and are fairly accurate, they cannot distinguish between an ongoing infection with HCV replicative activity and a past infection where HCV has been cleared, spontaneously or after a successful therapy. As a chronic infection is mostly asymptomatic until the late clinical stages, there is a compelling need to detect active HCV infection by simple and reproducible methods. On this purpose, the clinical guidelines have suggested to search for the HCV ribonucleic acid (HCV-RNA) after anti-HCV has been detected, but this second step carries several limitations especially for population screening. The availability of fast and automated serological assays for the hepatitis C core antigen (HCVAg) has prompted an update of the guidelines that now encompass the use of HCVAg as a practical alternative to HCV-RNA, both for screening and monitoring purposes. In this paper, we summarize the features, benefits and limitations of HCVAg testing and provide an updated compendium of the evidences on its clinical utility and on the indications for use.

HCV core antigen is a useful predictor during pegylated-interferon/ribavirin therapy in patients with hepatitis C virus genotype 1b

Enzyme immunoassays for quantifying hepatitis C virus (HCV) core antigen (Ag) have been proposed as an alternative to HCV RNA detection. The present study aimed to investigate the early kinetics of serum HCVcAg and its usefulness in predicting virological responses.The clinical data of 135 patients with chronic hepatitis C treated with pegylated interferon alpha (PEG-IFN-α) and ribavirin was retrospectively collected. The patients were grouped according to their treatment outcomes as follows: sustained virological response (SVR), nonsustained virological response (N-SVR), and relapse.Higher HCVcAg and HCV RNA levels were observed in patients in the N-SVR group than in the other groups at baseline. HCVcAg better predicted rapid virological response (RVR) compared with HCV RNA and had a predictive value similar to that of HCV RNA for SVR and early virological response. In the relapse group, HCV RNA decreased to 0 after 48 weeks, whereas HCVcAg was still detectable, indicating that HCVcAg more sensitively predicted relapse in antiviral therapy than HCV RNA.For patients treated with PEG-INF-α and ribavirin, HCVcAg may more sensitively predict relapse than HCV RNA.

Hepatitis C core antigen highly correlated to HCV RNA

Hepatitis C virus core antigen (HCV-Ag) immunoassay has been proposed as a more cost and time efficient one-step alternative to the current two-step screening and diagnostic process. This study investigates the correlation between the HCV-Ag immunoassay and the current gold standard of Hepatitis C Virus (HCV) ribonucleic acid (RNA) molecular assay. Stored sera of 221 consecutive treatment-naive patients tested anti-HCV positive were selected to undergo both HCV-Ag immunoassay and HCV RNA molecular assay. Active infection status and HCV genotype were determined using both assays, and correlation was calculated using a logarithmic scale. Among 221 anti-HCV-positive sera, 197 were positive for both HCV Ag (≥3 fmol/L) and HCV RNA (>15 IU/mL), 22 were negative for both tests, while 2 were positive to HCV RNA only. The sensitivity and specificity for HCV Ag in predicting HCV RNA were 99% and 100%, respectively. Out of 199 patients (90%) tested positive for HCV viremia, 107 (56%) were of genotype 1, 77 (38.7%) of genotype 2 and 15 of other genotypes. Analysis of 221 anti-HCV-positive patient sera found a strong positive correlation between HCV RNA and HCV-Ag (r = 0.960, p < 0.001). Genotype 1 (log [HCV RNA] = 0.988 x log [HCV-Ag] + 2.768), with correlation coefficient 0.945, exhibited a stronger correlation than genotype 2 (log [HCV RNA] = 0.859 x log [HCV-Ag] + 2.859; r = 0.862). Given the strong positive correlation between HCV-Ag immunoassay and HCV RNA molecular assay in genotyping affected individuals, we propose that HCV-Ag immunoassay is a more cost and time efficient alternative to the current two-step diagnostic process.

Identifying cost-effective screening algorithms for active hepatitis C virus infections in a high prevalence setting

OBJECTIVE

To evaluate the cost-effectiveness of different screening patterns for active chronic hepatitis C virus (HCV) infections utilizing the hepatitis C core antigen test compared to standard care in the context of a general screening program in a high-prevalence country.

METHODS

This study developed a decision analytic model to estimate the cost-effectiveness of four screening algorithms for the detection of active HCV infections among asymptomatic individuals with an unknown HCV status in a context of high (>5%) HCV prevalence. Three algorithms started with a serological test for antibodies (AB) followed by a nucleic acid test for HCV-RNA (RNA), the HCVAg (AG) assay, or both. An additional single marker screening strategy with AG was added to the analysis. By the example of the Republic of Georgia, strategies were compared in terms of total costs for screening and diagnosis of an active infection from a health system perspective.

RESULTS

Replacing RNA with AG for confirmation of positive AB identified fewer active infections (-110 per 100,000 screened subjects) at significantly reduced total costs (-$2.74 per screened) and costs per diagnosed infection (-$44). Adding a subsequent RNA confirmatory test on AG negative results captured at least the same rate compared to the standard (AB followed by RNA) at still reduced costs (-$1.16 per subject screened, -$22 per case detected). Utilizing AG as the frontline test revealed the highest detection rate (97.9%) at the highest costs (+$3.80 per subject, +$323 per case detected vs standard).

CONCLUSION

A combined pattern of HCV AB screening followed by sequential confirmation with AG and RNA on AG negatives would provide equal or better diagnostic performance at lower cost over a broad range of scenarios. Potential long-term consequences of screening strategies to patients and society have to be considered, since the latency period for HCV to develop into severe liver disease is long.

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.

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.

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.

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.

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).

Evolving strategy for HCV testing in an Italian tertiary care hospital

BACKGROUND

Diagnostic tests for hepatitis C virus (HCV) infection should be adapted according to the clinical status of the patient.

OBJECTIVES

We exploited the application of different HCV diagnostic algorithms in a tertiary care hospital practice.

STUDY DESIGN

The laboratory clinical reports to the medical orders for HCV testing during three years were clustered by different combinations of assays for anti-HCV antibodies (HCV Ab) (screening and confirmatory), HCV nucleic acid (HCV-RNA), HCV core antigen (HCV Ag). The latter was the first-line assay in acute HCV infections requiring a rapid assessment of the infectious state.

RESULTS

The majority (91.9%) of the 2726 subjects whose samples were analyzed were inpatients. Most of the patients/subjects were tested for clinical suspicion of viral hepatitis (49.2%), or occupational accident to health care professionals (20.0%). On 66% of samples HCV Ag test alone was performed and resulted positive in 116 cases (6%), while it was detected in 50.3% of anti-HCV positive samples. The agreement between HCV Ag and HCV-RNA was very high (k=0.97); HCV Ag positivity rates increased according to the signal of the HCV Ab screening test.

CONCLUSIONS

The use of different testing strategies according to the patients' history and clinical status allowed a significant reduction of the number of tests performed and the time needed to provide a diagnostic response useful for patients' management without compromising the overall diagnostic accuracy for HCV infection.

Hepatitis C virus screening to reveal a better picture of infection

Antiviral therapy for hepatitis C virus (HCV) infection will be the next revolution in clinical virology. Sensible planning for treatment is needed, starting with population-screening policies ideally using the HCV core antigen. This will result in a more defined picture of the silent spread of HCV.

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.

The correlation between hepatitis C core antigen and hepatitis C virus RNA levels with respect to human immunodeficiency virus status, hepatitis C virus genotype and interferon-lambda-4 polymorphism

OBJECTIVES

Serum hepatitis C virus (HCV) core antigen (HCVcAg) concentrations correlate with HCV RNA levels in HCV monoinfected patients. Data in HCV/HIV coinfected patients are still limited. We aim to compare the use of HCVcAg measurement with respect to HIV status, HCV genotypes, interferon-lambda-4 (IFNL4) polymorphism and clinical parameters.

METHODS

We analyzed an untreated cohort of 104 patients with HCV monoinfection and 85 patients with HCV/HIV coinfection. Serum HCVcAg was measured by a commercial chemiluminescent microparticle immunoassay. The presence of IFNL4 polymorphism ss469415590 was identified by real-time PCR.

RESULTS

log10 HCVcAg levels were significantly correlated with corresponding log10 HCV RNA levels (r = 0.889, p < 0.001), but not with ALT levels and liver stiffness. The correlation between HCV RNA and HCVcAg was particularly high in coinfected patients and those with high viremia. Mean log10 HCVcAg concentration was significantly higher in coinfected patients than in monoinfected patients. Patients harboring the TT/TT genotype of ss469415590 had significantly higher levels of log10 HCVcAg than those with the non-TT/TT genotype. HCVcAg levels were similar across HCV genotypes.

CONCLUSIONS

HCVcAg concentrations had an excellent correlation with HCV RNA levels, particularly in HCV/HIV-coinfected individuals and might be associated with IFNL4 polymorphism. HCVcAg testing could be used as an alternative to HCV RNA assays in resource-limited settings.

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.

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

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

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.

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.

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.