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.

HCV core antigen plays an important role in the fight against HCV as an alternative to HCV-RNA detection.

OBJECTIVE: To discuss the clinical significance of HCV-cAg testing in the diagnosis, activity determination, and monitoring of therapeutic effectiveness of HCV infection and its advantages compared with HCV-RNA and anti-HCV antibodies detection. METHODS: By summarizing the published literature, the advantages and significance of HCV core antigen detection were sought. RESULTS: The expression of HCV-cAg is highly consistent with that of HCV-RNA, but compared with HCV-RNA, detection of HCV-cAg is easy to operate, time saving, and low cost. HCV-cAg can be detected within 12~15 days after infection, and the window period can be shortened by5~7 weeks. HCV-cAg is a serological indicator of virus replication, which can distinguish previous infection of HCV or current infection. HCV-cAg detection is more suitable for immunocompromised, hemodialysis, organ transplant patients. HCV-cAg also can be used to monitor antiviral efficacy and predict sustained virological response (SVR). CONCLUSION: HCV core antigen has similar clinical sensitivity to NAT and can be used as a substitute for HCV-RNA in the diagnosis of virus infection. Combined detection of HCV-cAg and antibody serology can help doctors detect HCV infection earlier, accurately diagnose different stages of HCV infection, and evaluate the therapeutic effect of antiviral drugs, which are beneficial in the prevention and treatment of hepatitis C.

Current position of viral load versus hepatitis C core antigen testing. / Posición actual de la carga viral frente a la determinación de antígeno core del virus de la hepatitis C.

Quantification of hepatitis C virus (HCV) RNA (viral load) is the most widely used marker to diagnose and confirm active HCV infection. The HCV core antigen forms part of the internal structure of the virus and, like HCV RNA, its detection also indicates viral replication and presents certain advantages over viral load testing such as its lower cost, the greater stability of the target, the possibility of working with the same primary tube as that used for HCV serology, and the rapidity of obtaining results, since there is no need to work in batches, unlike the situation with most viral load platforms. Although the core antigen has lower analytical sensitivity than HCV RNA for the detection of low viremia levels, several studies and guidelines have already shown their utility in the identification of patients with active HCV infection. This article summarises current platforms for viral load determination, including point-of-care systems, and also reviews the indications attributed to this marker by the main HCV treatment guidelines. The article also reviews the characteristics of HCV core antigen, the available platforms for its determination, its correlation with viral load determination, and the indications for this marker in the distinct guidelines.

Hepatitis C virus core antigen as a possible alternative for evaluation of treatment effectiveness after treatment with direct-acting antivirals.

Background: Chronic hepatitis C is a major public health problem around the world. In monitoring treatment efficacy, although costly and labour-intensive methods of molecular biology are often used, much cheaper and technically easier serological methods evaluating the concentration of HCV core antigen in serum are available. We evaluated HCVcAg quantification as a possible assessment of the treatment efficacy instead of HCV RNA quantification.Methods: We collected 514 serum samples from treated HCV infected patients. Quantitative evaluation of HCV RNA and HCVcAg was carried out before treatment, at the end of treatment, and at least 12 weeks following treatment termination. HCV RNA was determined by automated assay (Roche COBAS) and HCVcAg quantitation with ARCHITECT ci8200 analyser.Results: There was a significant correlation between HCVcAg and HCV RNA concentrations at baseline and follow-up visits, but not at the end of treatment. Among samples collected before the treatment, at the end of treatment and follow-up visit, concordance of HCV RNA and HCVcAg reached level of 98.1%, 98.9% and 98.7%, respectively. Diagnostic sensitivity, specificity, positive and negative predictive values of HCVcAg detection were >97%.Conclusions: HCVcAg measurement could be an alternative for determining HCV treatment efficacy after chemotherapy and could be an option in the diagnosis of HCV infection.

Evaluation of a hepatitis C virus core antigen assay from venepuncture and dried blood spot collected samples: A cohort study.

The global scale-up of hepatitis C virus (HCV) diagnosis requires simplified and affordable HCV diagnostic pathways. This study evaluated the sensitivity and specificity of the HCV Architect core antigen (HCVcAg) assay for detection of active HCV infection in plasma and capillary whole blood dried blood spots (DBS) compared with HCV RNA testing in plasma (Abbott RealTime HCV Viral Load). Samples were collected from participants in an observational cohort enrolled at three sites in Australia (two-drug treatment and alcohol clinics and one homelessness service). Of 205 participants, 200 had results across all samples and assay types and 186 were included in this analysis (14 participants receiving HCV therapy were excluded). HCV RNA was detected in 29% of participants ([95% CI: 22.6-36.1], 54 of 186). The sensitivity of HCVcAg for detection of active HCV infection in plasma was 98.1% (95% CI: 90-100) and 100% (95% CI: 93-100) when compared to HCV RNA thresholds of ≥12 and ≥1000 IU/mL, respectively. The sensitivity of the HCVcAg assay for detection of active HCV infection in DBS was 90.7% (95% CI: 80-97) and 92.5% (95% CI: 82-98) when compared to HCV RNA thresholds of ≥12 and ≥1000 IU/mL, respectively. The specificity of HCV core antigen for detection of active infection was 100% (95% CI: 97-100) for all samples and RNA thresholds. These data indicate that the detection of HCVcAg is a useful tool for determining active HCV infection; to facilitate enhanced testing, linkage to care and treatment particularly when testing plasma samples are collected by venepuncture.

The correlation of HCV RNA and HCV core antigen in different genotypes of HCV.

BACKGROUND: To analyze the correlation of HCV RNA and HCV core antigen (HCV cAg) in different genotypes of HCV. METHODS: One hundred and six patients who were diagnosed with HCV infection by HCV RNA test were included in the study. HCV genotypes were detected by PCR fluorescent probe. Detected HCV cAg's expression in serum quantitatively and qualitatively with chemiluminescent micro-particle immuno assay (CMIA) and enzyme-linked immunosorbent assay (ELISA), respectively, and compared positive rates. Analyzed the correlation of HCV RNA and HCV cAg in different genotypes. RESULTS: Distribution of HCV genotypes in 106 HCV infected patients were as follows: 1b genotype 46 (43.4%); 2a genotype 7 (6.6%); 3a genotype 18 (17.0%); 3b genotype 3 (2.8%); 6a genotype 9 (8.5%); 1b/3b mixed type 13 (12.3%); and unidentified type 10 (9.4%). Positive rates of HCV cAg detected by CMIA and ELISA were 100% and 56%, respectively, with statistical significance (χ2  = 60.38, P = 0.000). HCV cAg in 1b genotype group was higher than that in 3b and 1b/3b genotype groups, with statistical significance (U = 3.0, P = 0.006, U = 165, P = 0.014). HCV RNA and HCV cAg in genotype 1b demonstrated a positive correlation (r = 0.894, P = 0.04). CONCLUSION: Major genetic subtype of HCV genotype was 1b. Compared with ELISA, detection of HCV cAg by CMIA increased the positive rate and facilitated early diagnosis and treatment of HCV-infected patients. With the increase in HCV RNA load and the expression of HCV cAg, HCV cAg could be an early indicator for the diagnosis of HCV infection in 1b genotype.

Assessment of reproducibility of a VP7 Blocking ELISA diagnostic test for African horse sickness.

The laboratory diagnosis of African horse sickness (AHS) is important for: (a) demonstrating freedom from infection in a population, animals or products for trade (b) assessing the efficiency of eradication policies; (c) laboratory confirmation of clinical diagnosis; (d) estimating the prevalence of AHS infection; and (e) assessing postvaccination immune status of individual animals or populations. Although serological techniques play a secondary role in the confirmation of clinical cases, their use is very important for all the other purposes due to their high throughput, ease of use and good cost-benefit ratio. The main objective of this study was to support the validation of AHS VP7 Blocking ELISA up to the Stage 3 of the World Animal Health Organization (OIE) assay validation pathway. To achieve this, a collaborative ring trial, which included all OIE Reference Laboratories and other AHS-specialist diagnostic centres, was conducted in order to assess the diagnostic performance characteristics of the VP7 Blocking ELISA. In this trial, a panel of sera of different epidemiological origin and infection status was used. Through this comprehensive evaluation we can conclude that the VP7 Blocking ELISA satisfies the OIE requirements of reproducibility. The VP7 Blocking ELISA, in its commercial version is ready to enter Stage 4 of the validation pathway (Programme Implementation). Specifically, this will require testing the diagnostic performance of the assay using contemporary serum samples collected during control campaigns in endemic countries.

Confirmation of HCV viremia using HCV RNA and core antigen testing on dried blood spot in HIV infected peoples who inject drugs in Vietnam.

BACKGROUND: Nucleic acid tests performed on blood samples collected on Dried Blood Spot (DBS) and detection of HCV core antigen (HCVcAg) are two approaches that may facilitate access to HCV diagnosis in low and middle incomes countries. In this study we evaluate HCV RNA and HCV antigen testing on DBS in HIV/HCV co-infected peoples who inject drugs in Vietnam. METHOD: One hundred and four HIV/HCV seropositive patients managed in outpatient care at the Haiphong Viet Tiep hospital were included in this study from February to March, 2014 (ANRS 12262 study). RESULTS: Eighty-six subjects were tested positive for HCV RNA in serum, median (IQR): 6.9 log10 IU/ml (5.6-7.4 log10 IU/ml). Genotypes consisted of 57 G1 (69%), 3 G3 (4%), and 22 G6 (27%). HCV RNA was detected on DBS specimens in 79 out 86 subjects with chronic hepatitis C (sensitivity 92.5%; 95% CI: 85.1-96.9%). HCV RNA level on DBS and serum was moderately correlated (r = 0.24; p = 0.05) suggesting a degradation of HCV RNA due to transportation and storage conditions. HCVcAg was detected in 75/86 dB specimens (sensitivity: 87.2%; 95% CI: 78.3-93.4%), with a strong positive relationship between DBS HCVcAg and serum HCV RNA levels (r = 0.80; P < 0.0001). CONCLUSIONS: Quantification of HCVcAg on DBS appears to benefit from substantial stability under prolonged storage conditions but with a lower analytical sensitivity compared to DBS HCV RNA testing. Detection of HCV RNA on DBS is an interesting approach for confirming viral replication in HCV seropositive persons but the impact of pre-analytical conditions on the integrity of HCV RNA needs to be controlled.

HCV core antigen as an alternative to HCV RNA testing in the era of direct-acting antivirals: retrospective screening and diagnostic cohort studies.

BACKGROUND: Direct-acting antivirals for chronic hepatitis C (HCV) infection have reduced the need for on-treatment HCV RNA monitoring. We assessed the accuracy and cost implications of using HCV core antigen testing to replace HCV RNA testing for confirmation of diagnosis, on-treatment monitoring, and determination of sustained virological response (SVR). METHODS: In a retrospective screening cohort study, de-identified residual serum from unselected samples were obtained from commercial laboratories in Ontario, Canada. Samples from each 5-year age-sex band from birth years 1945-74 collected from Aug 1, 2014, to Feb 28, 2015, were included. All samples that tested positive for HCV antibodies, and 10% of samples that tested negative for HCV antibodies, were tested for HCV core antigen and HCV RNA. A retrospective clinical cohort study was also done using blood samples from patients with confirmed HCV infection collected at four tertiary academic centres: one in Canada, two in Germany, and one in the USA. For assessment of SVR, we included samples from patients who started direct-acting antiviral-based treatment (excluding telaprevir and boceprevir) with or without peginterferon, ribavirin, or both, from Jan 1, 2014, to March 31, 2015. To ensure inclusion of adequate numbers for analysis, patients who relapsed after any treatment regimen were included. Serum samples included in the study were from baseline, week 4 on-treatment (only for patients treated with direct-acting antivirals), end of treatment, and week 12 or 24 of follow-up. The sensitivity and specificity of core antigen testing as a diagnostic tool was assessed in the screening cohort, using HCV RNA as a reference. The sensitivity and specificity of core antigen testing as well as its concordance with HCV RNA testing in the clinical cohort was assessed at baseline, week 4 on-treatment, and at weeks 12 or 24 after the end of treatment in patients undergoing therapy with direct-acting antivirals. The cost-effectiveness of core antigen testing with and without confirmatory HCV RNA testing for negative samples was also assessed. FINDINGS: From 10 006 samples in the screening cohort, 75 of 80 viraemic (HCV RNA-positive) samples tested positive for HCV core antigen (sensitivity 94%, 95% CI 86-98), and none of the 993 HCV RNA-negative samples tested positive for HCV core antigen (specificity 100%, 95% CI 94-100). The five viraemic samples that tested negative for HCV core antigen had low corresponding HCV RNA concentrations. In the clinical cohort, two (1%) of 202 baseline samples tested negative for HCV core antigen; one had a low HCV RNA concentration (468 IU/mL), the other had a high HCV RNA concentration (>2 000 000 IU/mL). By week 4 of treatment, HCV core antigen concentrations decreased in all patients but were not predictive of SVR. Although there was good concordance between HCV RNA and HCV core antigen results at 12 weeks after the end of treatment (r=0·97; p<0·0001), three of the 148 patients who achieved SVR at 12 weeks tested HCV core antigen positive. 12 weeks after the end of treatment, HCV core antigen was undetectable in one (1%) of 71 samples from patients who were identified as having relapsed according to HCV RNA detection. On-treatment and end-of-treatment testing of core antigen or HCV RNA provided little clinical value. The use of HCV core antigen testing as a confirmatory diagnostic strategy was cost saving relative to HCV RNA testing, with a reduction of CAD$0·29-3·70 per patient screened depending on whether HCV RNA testing was used to confirm HCV core antigen-negative results. INTERPRETATION: These data support the use of HCV core antigen testing to document HCV viraemia in a cost-saving diagnostic algorithm. In a treatment setting, HCV core antigen testing can be used instead of HCV RNA testing for diagnosis and documentation of treatment adherence, but it might not be adequate to determine SVR. This approach might improve access to care, particularly in low-income and middle-income countries. FUNDING: Abbott Diagnostics and Toronto Centre for Liver Disease.

Production and application of anti-nucleoprotein IgY antibodies for influenza A virus detection in swine.

Influenza A virus (IAV) causes an important respiratory disease in mammals and birds leading to concerns in animal production industry and public health. Usually, antibodies produced in mammals are employed in diagnostic tests. However, due to animal welfare concerns, technical advantages and the high cost of production, alternatives to the production of antibodies in mammals have been investigated. The aim of this study was to produce egg yolk immunoglobulin (IgY) in laying hens against a highly conserved protein (nucleoprotein- NP) of IAV and to evaluate the application of anti-NP IgY antibodies in virus detection by immunocytochemistry (ICC) and immunohistochemistry (IHC). Three laying hens of the White Leghorn line were inoculated seven times with a recombinant NP protein and their eggs collected seven days after the 3rd, 5th and 7th inoculations. Immunoglobulin Y antibodies were purified from egg yolk through precipitation with ammonium sulfate. The titers and specificity of the purified antibodies were determined by ELISA, western blotting, ICC and IHC. High levels of specific anti-NP antibodies were detected by ELISA after the 5th inoculation, reaching a peak after the 7th inoculation. The mean yield of total protein in yolk after the 7th inoculation was 13.5 mg/mL. The use of western blotting and ICC demonstrated that anti-NP IgY binds specifically to NP protein. Moreover, the use of anti-NP IgY antibody in ICC test revealed positive staining of MDCK cells infected with IAV of the three subtypes circulating in swine (H1N1, H1N2, and H3N2). However, no staining was observed in lung tissues through the IHC test. The data obtained showed that anti-NP IgY antibodies bound specifically to influenza virus NP protein, detecting the main virus subtypes circulating in swine, reinforcing their usefulness in the influenza diagnosis.

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.

Hepatitis C virus core antigen for screening organ donors and recipients.

Organ donors and recipients are routinely screened for hepatitis C virus (HCV) infection, typically via anti-HCV detection. We analyze the utility of an alternative HCV core antigen (HCV-Ag) quantification system, the ARCHITECT HCV Ag Assay, in this setting. We simultaneously tested 315 samples from potential organ donors and recipients using two chemiluminescent microparticle immunoassays: ARCHITECT Anti-HCV and HCV Ag (Abbott, Germany). HCV-Ag was detected in 81 of the serum samples (25.71%) and anti-HCV in 87 (27.62%). Seventy-five of the HCV-Ag-positive samples were positive for anti-HCV (92.59%). Overall concordance between the two assays was 94.29%. Of the six HCV-Ag-positive/anti-HCV-negative patients, five had HCV-Ag values <32 fmol/L, and the sixth had a concentration of 477.50 fmol/L (viral load, 137,000 IU/mL). The HCV AG Assay detects HCV infections missed by the Anti-HCV Assay. Both markers should be used to screen for HCV infection in potential organ donors and recipients.

Hepatitis C virus core antigen in the management of patients treated with new direct-acting antivirals.

We evaluated the utility of Architect core antigen assay® Abbott Diagnostics (HCVAg) for monitoring patients with HCV infection and compared to HCV-RNA quantification (Cobas Ampliprep TaqMan-Roche Diagnostics). Samples from 262 patients were studied. Mean baseline HCV RNA and HCVAg levels were similar for responders (6.2 log IU/mL and 3.4 log fmol/L) and non-responders (6.1 log IU/mL and 3.2 log fmol/L), respectively. Only 10 patients failed to achieve SVR12 and all were detected by both assays. To evaluate HCVAg quantification as a tool for the detection of failure to DAAs, we performed a retrospective study of 132 non-responder patients. Mean HCV RNA and HCVAg levels at the time of detection of therapeutic failure were 5.88±0.97 log IU/mL and 3.19±0.79 log fmol/L, respectively. HCVAg (>3 fmol/L) was detected in 130/132 patients (98.5%). HCVAg assay was useful for patient selection and for evaluating virological response to DAAs in the real world.

Hepatitis C virus core antigen: A simplified treatment monitoring tool, including for post-treatment relapse.

BACKGROUND: Simple, affordable diagnostic tools are essential to facilitate global hepatitis C virus (HCV) elimination efforts. OBJECTIVES: This study evaluated the clinical performance of core antigen (HCVcAg) assay from plasma samples to monitor HCV treatment efficacy and HCV viral recurrence. STUDY DESIGN: Plasma samples from a study of response-guided pegylated-interferon/ribavirin therapy for people who inject drugs with chronic HCV genotype 2/3 infection were assessed for HCV RNA (AmpliPrep/COBAS Taqman assay, Roche) and HCVcAg (ARCHITECT HCV Ag, Abbott Diagnostics) during and after therapy. The sensitivity and specificity of the HCVcAg assay was compared to the HCV RNA assay (gold standard). RESULTS: A total of 335 samples from 92 enrolled participants were assessed (mean 4 time-points per participant). At baseline, end of treatment response (ETR) and sustained virological response (SVR) visits, the sensitivity of the HCVcAg assay with quantifiable HCV RNA threshold was 94% (95% CI: 88%, 98%), 56% (21%, 86%) and 100%, respectively. The specificity was between 98 to 100% for all time-points assessed. HCVcAg accurately detected all six participants with viral recurrence, demonstrating 100% sensitivity and specificity. One participant with detectable (non-quantifiable) HCV RNA and non-reactive HCVcAg at SVR12 subsequently cleared HCV RNA at SVR24. CONCLUSIONS: HCVcAg demonstrated high sensitivity and specificity for detection of pre-treatment and post-treatment viraemia. This study indicates that confirmation of active HCV infection, including recurrent viraemia, by HCVcAg is possible. Reduced on-treatment sensitivity of HCVcAg may be a clinical advantage given the moves toward simplification of monitoring schedules.

Induction of H7N9-Cross-Reactive Antibody-Dependent Cellular Cytotoxicity Antibodies by Human Seasonal Influenza A Viruses that are Directed Toward the Nucleoprotein.

Antibodies that mediate antibody-dependent cellular cytotoxicity (ADCC) against avian influenza virus subtypes, including H7N9 and H5N1, have been detected in human sera. Using NK cell activation and NK cytotoxicity assays, we compared ADCC-mediating antibodies (ADCC-Abs) in sera collected from healthy infants, children and adults against H7N9 virus-infected cells and recombinant hemagglutinin (HA), neuraminidase (NA), and nucleoprotein (NP) proteins. High titers of ADCC-Abs against H7N9 virus-infected cells were detected in sera from adults and children but not infants. ADCC-Abs titers directed against H7N9 HA or NA proteins. Further analysis showed that ADCC-Abs titers were significantly higher toward H7N9 NP, as compared with H7N9 HA or NA proteins, and correlated strongly with ADCC-Abs titers against H7N9 virus-infected cells. Indeed, ADCC-Abs to NPs of seasonal H1N1 and H3N2 viruses correlated strongly with ADCC-Abs to H7N9 NP, suggesting that seasonal influenza infections and vaccinations may induce these cross-reactive antibodies. Targeting ADCC-Abs to internal proteins may be a potential mechanism of universal vaccine design.

Quantification of Core Antigen Monitors Efficacy of Direct-acting Antiviral Agents in Patients With Chronic Hepatitis C Virus Infection.

BACKGROUND & AIMS: Widespread use of direct-acting antiviral (DAA) agents to treat patients with hepatitis C virus (HCV) infection has reduced the need for monitoring of HCV RNA levels, because viral kinetics do not predict sustained virologic response (SVR) to these drugs. However, the performance of cheaper tests such as the assay to quantify HCV core antigen (HCV Ag) has not been determined. We investigated the accuracy of the HCV Ag test in predicting which patients receiving DAAs will achieve SVRs at week 12 (SVR12). METHODS: We performed a prospective study of 58 patients infected with HCV genotypes 1-5 (45% with HCV genotype 1, 72% with cirrhosis) receiving DAA therapy from the Liver Center at the Università degli Studi of Milan in Italy from January to March 2015. We collected blood samples and measured levels of HCV Ag and HCV RNA at baseline, after 2 and 4 weeks of treatment, the end of treatment, and 12 weeks after treatment ended. We compared the ability of these assays to predict which patients would have SVR12. RESULTS: The median baseline level of HCV RNA was 5.79 log10 IU/mL (range, 3.51-7.31 log10 IU/mL) and of HCV Ag was 3226.87 fmol/L (range, 17.30-54,927.00 fmol/L). HCV Ag became undetectable in 71% of patients at week 2, 84% at week 4, and 93% at the end of treatment. HCV RNA became undetectable in 10% of patients at week 2, 43% at week 4, and 100% at the end of treatment (P < .0001). Concordance between the tests in identifying patients who would achieve SVR12 was 40% at week 2, 55% at week 4, and 95% at the end of treatment. Fifty-three of 58 patients (91%) achieved an SVR12; the test for HCV Ag identified 97% of these patients. The tests for HCV Ag and HCV RNA predicted which patients would have SVR12 with positive predictive values of 90% vs 83%, respectively, at week 2 and 89% vs 92%, respectively, at week 4. CONCLUSIONS: Tests that measure HCV Ag monitor efficacy of DAA therapy for HCV infection as well as assays that measure HCV RNA and can be recommended for clinical practice. However, measurement of HCV RNA after treatment can rule out relapse in HCV Ag-positive patients.

Course of hepatitis C virus (HCV) RNA and HCV core antigen testing are predictors for reaching sustained virologic response in liver transplant recipients undergoing sofosbuvir treatment in a real-life setting.

BACKGROUND: Hepatitis C virus (HCV) infection is associated with reduced graft survival in orthotopic liver transplant recipients. Treatment with the new direct-acting antivirals (DAAs) is safe and efficient, but no reliable predictive factors for sustained virologic response (SVR) have been identified so far. The HCV core antigen assay (HCV-core-Ag) is a new, inexpensive, and efficient method to detect viral antigens, but the value of this technique to predict treatment response in orthotopic liver transplantation (OLT) patients is still unclear. METHODS: All OLT patients who were treated with a sofosbuvir-based antiviral regimen at our center between March 2014 and August 2014 were included in the analysis (n = 20). HCV-core-Ag and HCV RNA (polymerase chain reaction [PCR]) were determined at each visit. Primary endpoints of this study were SVR at 4 or 12 weeks after end of treatment (SVR 4 and SVR 12). RESULTS: HCV-core-Ag tested negative after a median of 2 weeks (range 1-16 weeks) while PCR tests became negative after a median of 4 weeks (range 2-12 weeks). Time until PCR negativity and until HCV-core-Ag negativity showed a good correlation (R = 0.711, P < 0.001, Fig. ). Seventeen of 20 patients (85%) achieved SVR 12. SVR 12 was associated with a short time interval between treatment start and HCV PCR negativity (P = 0.005) or HCV-core-Ag negativity (P = 0.003, Mann-Whitney test). No severe side effects were observed. CONCLUSIONS: DAA treatment is safe and well tolerated in OLT. The time points of HCV-core-Ag loss and PCR negativity were predictors of SVR 12.

Significance of the hepatitis C virus core antigen testing as an alternative marker for hepatitis diagnosis in Egyptian patients.

OBJECTIVE: Hepatitis C virus (HCV) core antigen (Ag) quantification by enzyme-immunoassays has been proposed as an economic and simpler alternative to HCV RNA detection. The current study was undertaken to assess the significance of HCV core antigen assay for the diagnosis of chronic HCV infection and monitoring response to antiviral therapy in Egyptian patients. PATIENTS AND METHODS: Sixty three HCV antibody positive patients and ten interferon-treated patients were included in the current study. The included patients were divided according to their viral load into four groups as follows; group I (n=10): HCV RNA loads ≤ 10000 IU/ml, group II (n=20): HCV RNA loads > 10000 ≤ 100000 IU/ml, group III (n=33): HCV RNA loads >100000 IU/ml and group IV (n=10): interferon-treated HCV patients with a negative HCV RNA.  Serum HCV core Ag and RNA loads were assayed and their correlations, including linear regression lines, were calculated. RESULTS: HCV core Ag exhibited a non-significant (p > 0.05) difference between all the studied groups. Concerning, group I patients, HCV core Ag levels and HCV RNA loads were positively correlated, with a correlation coefficient of 0.73 (p < 0.05). Group II and III showed stronger correlations; the recorded values were 0.81 (p < 0.0001) and 0.94 (p < 0.0001) for group II and III, respectively. CONCLUSIONS: HCV core Ag test can be used as an alternative to HCV RNA tests to evaluate chronic infection when the HCV RNA test is unavailable, but is not reliable enough for treatment monitoring.