Evaluation of a Hepatitis C Virus Core Antigen Assay in Plasma and Dried Blood Spot Samples

Impact of storage time in dried blood samples (DBS) and dried plasma samples (DPS) for point-of-care hepatitis C virus (HCV) RNA quantification and HCV core antigen detection

The scale-up of hepatitis C virus (HCV) diagnosis and treatment requires affordable and simple tools to improve access to care, especially in low- and middle-income settings with limited infrastructure or high-risk populations. Dried blood and plasma samples (DBS and DPS) are useful alternative for hepatitis C detection in settings lacking adequate infrastructure. We evaluated the performance of DBS and DPS vs plasma in a point-of-care HCV RNA quantitative assay (Xpert HCV Viral Load-Cepheid), and compared HCV core antigen (HCVcAg) detection by the Architect HCV core antigen assay (Abbott) in DBS vs serum. The dried samples were stored at room temperature for different storage times to reproduce the time from sampling to testing in settings with centralized diagnosis or when testing mobile populations. HCV RNA quantification in DBS and DPS presented 100% sensitivity and specificity and a high correlation for up to 3 months of storage. HCV viremia showed a mean decrease of 0.5 log10 IU/mL (DBS) and 0.3 log10 IU/mL (DPS) for storage times up to 1 month. Architect HCVcAg detection presented high sensitivity/specificity (96%/100%) in DBS tested immediately after sampling, decreasing to 86% sensitivity after 7 days of storage. However, sensitivity increased when an optimized cut-off was applied for each storage time. We conclude that DBS and DPS are suitable samples for HCV RNA detection and quantification, being DPS more reliable for shorter storage times. DBS can be also used for HCVcAg qualitative detection and the sensitivity can be increased when adjusting the cut-off values. IMPORTANCE Hepatitis C infection remains a global burden despite the effectiveness of antivirals. In the WHO roadmap to accomplish HCV elimination by 2030, HCV diagnosis is one of the main targets. However, identifying patients in resource-limited settings and high-risk populations with limited access to healthcare remains a challenge and requires innovative approaches that allow decentralized testing. The significance of our research is in verifying the good performance of dried samples for HCV diagnosis using two different diagnostics assays and considering the effect of room temperature storage in this sample format. We confirmed dried samples are an interesting alternative for HCV screening and reflex testing in resource-limited settings or high-risk populations.

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%).

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

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

Resistant-Associated Substitutions Do Not Affect HCV RNA and HCV Core Antigen Clearance During Direct-Acting Antiviral Agent Treatment in a Real-World Setting

Background

Since oral direct-acting antiviral agents (DAAs) became available, the global hepatitis C treatment situation has undergone tremendous changes. However there are still many issues worthy of attention in treatment.

Methods

We selected 53 HCV-infected patients who were treated and followed up in the Peking University First Hospital from December 2017 to January 2021 to detect the RASs in HCV. Pearson correlation analysis was used to analyze HCV RNA and HCV cAg, the Fisher exact test and chi-square test was used to compare the effects of RASs on the rate of decline of HCV RNA and HCV core antigen (cAg) during DAA treatment.

Results

The RASs and its prevalence on the NS3 are mainly Y56F 2.56% (1/39), Q80K 23.08% (9/39), S122G 71.79% (28/39), and V170I 38.46% (15/39). On the NS5A were R30Q 10.53% (4/38), P32A 5.26% (2/38), P58S 2.63% (1/39), and Y93H 21.05% (8/38). On NS5B were C316N 71.05% (27/38), C451H 2.63% (1/38), and I585C 2.63% (1/38). There was no significant correlation between the RASs (Y93H, V179I, Q80K, S122G, C316N) and HCV genotype (p > 0.05). The baseline serum HCV RNA and HCV cAg had a significant medium-degree correlation (r = 0.601, p = 0.002). After 1 week of DAA treatment was weak correlation (r = 0.413, p = 0.032). Q80K, S122G, V170I, Y93H, and C316N had no effect on the clearance of HCV RNA and HCV cAg within the first week of DAA treatment (p>0.05).

Conclusion

The HCV genotype may have a limited impact on the presence of the five RASs (Y93H, V179I, Q80K, S122G, and C316N) as shown in this study. HCV RNA and HCV cAg have a correlation, especially at baseline is the highest; the appearance of some RASs has no effect on DAA treatment in most chronic hepatitis C patients.

Evaluation of hepatitis C virus antibody assay using dried blood spot samples

Early diagnosis of hepatitis C virus (HCV) infection is essential for prompt initiation of treatment and prevention of transmission, yet several logistical barriers continue to limit access to HCV testing. Dried blood spot (DBS) technology involves a simple fingerstick that eliminates the need for trained personnel, and DBS can be stored and transported at room temperature. We evaluated the use of DBS whole blood samples in the modified Abbott ARCHITECT anti-HCV assay, comparing assay performance against the standard assay run using DBS and venous plasma samples. 144 HCV positive and 104 HCV negative matched venous plasma and whole blood specimens were selected from a retrospective study with convenience sampling in Cameroon. Results obtained using a modified volume DBS assay were highly correlated to the results of the standard assay run with plasma on clinical samples and dilution series (R² = 0.71 and 0.99 respectively). The ARCHITECT Anti-HCV assay with input volume modification more accurately detects HCV antibodies in DBS whole blood samples with 100% sensitivity and specificity, while the standard assay had 90.97% sensitivity. The use of DBS has the potential to expand access to HCV testing to underserved or marginalized populations with limited access to direct HCV care.

Performance of HCV Antigen Testing for the Diagnosis and Monitoring of Antiviral Treatment: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

Active hepatitis C virus (HCV) infection is based on the detection of HCV RNA that it is effective but presents high cost and the need to hire trained personnel. This systematic review and meta-analysis is aimed at evaluating the diagnostic accuracy of HCV Ag testing to identify HCV cases and to monitor antiviral treatment including DAA treatment.

METHODS

The studies were identified through a search in PubMed, Lilacs, and Scopus from 1990 through March 31, 2020. Cohort, cross-sectional, and randomized controlled trials were included. Two independent reviewers extracted data and assessed quality using an adapted Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Our primary outcome was to determine the accuracy of HCV Ag detection for the diagnosis, which we estimated using random-effects meta-analysis.

RESULTS

Of 3,062 articles identified, 54 met our eligibility criteria. The studies described cohorts from 20 countries, including 14,286 individuals with chronic HCV individuals. Studies for ECLIA technology demonstrated highest quality compared to studies that used ELISA. The pooled sensitivity and specificity (95% CI) for HCV Ag detection of active HCV infection were 98.82% (95%CI = 98.04%; 99.30%) and 98.95% (95%CI = 97.84%; 99.49%), respectively. High concordance was found between HCV Ag testing and HCV RNA detection 89.7% and 95% to evaluate antiviral treatment.

CONCLUSIONS

According to our findings, HCV Ag testing could be useful to identify HCV active cases in low-resource areas. For antiviral treatment, HCV Ag testing will be useful at the end of treatment.

Cost effectiveness of simplified HCV screening-and-treatment interventions for people who inject drugs in Dar-es-Salaam, Tanzania

BACKGROUND

Compared to other countries in sub-Saharan Africa, Tanzania has a relatively progressive illicit drug harm reduction (HR) policy, through a predominantly opioid substitution therapy-based programme. However, access to hepatitis C virus (HCV) diagnosis and curative direct acting antiviral therapy remains elusive. We developed a cost-effectiveness model to evaluate a simplified HCV screening-and-treatment intervention amongst PWID in Dar-es-Salaam, Tanzania.

METHODS

A decision tree and Markov state transition model compared existing practice (no access to HCV viral confirmation and treatment) with the integration of point-of-care HCV screening and treatment within (1) existing HR services and (2) expansion to include PWID not currently engaged in HR. Outcome measures were screening, treatment, HR and disease-related costs per PWID, quality-adjusted life years (QALY) and disability adjusted life years (DALY). Cost-effectiveness was evaluated from a healthcare payer's perspective over a 30-year time horizon over a range of willingness-to-pay thresholds (USD$273 to USD$1,050). Both deterministic and probabilistic sensitivity analyses have been conducted.

RESULTS

Assuming a chronic HCV prevalence of 18.8%, screening-and-treatment in existing HR settings resulted in an ICER per QALY-gained and DALY averted of USD$633 and USD$1,161, respectively. Expanding to include an outreach programme for unengaged PWID yielded an ICER per QALY-gained and DALY-averted of USD$4,091 and USD$10,288. Factors affecting the sensitivity of the ICER value included the cost of HR and the health utility of non-cirrhotic disease states.

CONCLUSION

Simplified HCV screening and treatment of PWID has the potential to be cost-effective in Dar-es-Salaam, Tanzania. In practice, synergism of human and financial resources with established health programmes may offer a pragmatic solution to minimise operational costs.

Laboratory-based testing for hepatitis C infection using dried blood spot samples: A systematic review and meta-analysis of diagnostic accuracy

The use of dried blood spot (DBS) samples can facilitate the implementation of reflex testing by circumventing the need for centrifugation and freezing of venous blood samples. This systematic review assessed the accuracy of using DBS samples to diagnose chronic hepatitis C virus (HCV) infection. A comprehensive search was undertaken to identify articles published up to July 2020 evaluating the diagnostic accuracy of anti-HCV, HCV-RNA and HCV core antigen tests using DBS. Screening, data extraction, quality appraisal and Grading of Recommendations, Assessment, Development and Evaluations certainty of the evidence assessment were performed independently by two reviewers. Meta-analysis, meta-regression and sensitivity analyses were conducted. The evidence demonstrates that laboratory-based anti-HCV and HCV-RNA tests using DBS samples have high diagnostic accuracy. All comparisons were between DBS and venous samples. For the detection of anti-HCV, sensitivity was 95% (95% CI: 92%-97%) and specificity was 99% ([95% CI: 98%-99%]; n = 25; I²  = 81%; moderate certainty). For the detection of HCV-RNA, the sensitivity was 95% (95% CI: 93%-97%) and specificity was 97% ([95% CI: 94%-98%]; n = 20; I²  = 52%; moderate certainty). The sensitivity of HCV core antigen tests was 86% (95% CI: 79%-91%) and specificity was 98% ([95% CI: 94%-99%]; n = 5; I²  = 37%; low certainty) compared with HCV-RNA (the gold standard for detecting chronic HCV). DBS samples could facilitate diagnosis of chronic HCV infection as the necessary sequential tests (anti-HCV and then HCV-RNA or HCV core antigen) can be undertaken using the same blood sample. This could reduce loss of patient follow-up and support international efforts towards HCV elimination in both high and low prevalence settings.

Evaluation of Hepatitis C Virus Core Antigen Assay in a Resource-Limited Setting in Pakistan

The diagnosis of Hepatitis C virus (HCV) infection can be challenging due to its cost and a lack of access to centralized testing. There is an urgent need to develop simplified HCV testing algorithms. The aim of this study was to evaluate the performance characteristics of a Hepatitis C core antigen (HCVcAg) assay in a decentralized, resource-limited setting. This is a descriptive cross-sectional study from a highly endemic area of Karachi, Pakistan. Between October 2019 and July 2020, subjects aged 12 years and above who screened positive for HCV antibodies were simultaneously tested for HCV RNA (Xpert HCV Viral Load, GeneXpert^® IV, Cepheid, France) and HCVcAg (ARCHITECT HCV Ag assay, Abbott^® Diagnostics) to confirm active HCV infection. An Abbott ARCHITECT^® i1000SR Immunoassay Analyser was installed at a local district hospital as a point-of-care (POC) facility for HCVcAg testing, while samples for HCV RNA were tested in a central lab. Two hundred individuals (mean age 46.4 ± 14.5 years, 71.5% females), who screened positive for HCV antibody, were included in the study. HCV RNA was detected in 128 (64.0%) while HCVcAg was reactive in 119 (59.5%) cases. Performance of the Immunoassay Analyser was excellent with a higher throughput and quicker readout value compared to the GeneXpert System. The sensitivity and specificity of HCVcAg (≥10 fmol/L) at HCV RNA thresholds of ≥12 was 99.1% (95% CI: 95–100%) and 87.6% (95%CI: 78.4–94%). A strong agreement was observed between the HCVcAg assay and HCV RNA. The ARCHITECT HCV Ag assay showed high sensitivity and specificity compared to HCV RNA in a decentralized, resource-limited setting. It can therefore be used as a confirmatory test in HCV elimination programs, particularly for low-income countries such as Pakistan.

EASL recommendations on treatment of hepatitis C: Final update of the series☆

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease, with approximately 71 million chronically infected individuals worldwide. Clinical care for patients with HCV-related liver disease has advanced considerably thanks to an enhanced understanding of the pathophysiology of the disease, as well as developments in diagnostic procedures and improvements in therapy and prevention. These therapies make it possible to eliminate hepatitis C as a major public health threat, as per the World Health Organization target, although the timeline and feasibility vary from region to region. These European Association for the Study of the Liver recommendations on treatment of hepatitis C describe the optimal management of patients with recently acquired and chronic HCV infections in 2020 and onwards.

Diverse HCV Strains And HIV URFS Identified Amongst People Who Inject Drugs In India

Although the prevalences of HIV and HCV are significantly higher amongst PWID in India compared to the general population, the strains circulating within this group have not been well-characterized. Through subgenomic sequencing of viruses present in residual plasma from an HIV/HCV prevalence study conducted amongst PWID across five cities in India in 2016-2017, a total of N = 498 HCV and N = 755 HIV strains were classified from N = 975 study participants. Considerable HCV diversity was identified, with different strains predominating in each region of the country. Overall, the most common strain was genotype 3a (39.0%), with genotypes 1a (26.9%), 1b (3.0%), 1c (0.2%), 3b (20.7%), 3i (2.0%), 4a (0.2%), 4d (1.0%), 6 (1.8%), 6n (4.8%), 6 v (0.2%) and one unclassifiable recombinant specimen (0.2%) also identified. The majority of the HIV specimens were subtype C (96.7%), although subtype A (0.4%), CRF01_AE (0.4%) and unique recombinant forms (URFs, 2.5%) were also detected. Notably, the geographical restriction of HIV subtype A and CRF01_AE, and HCV genotypes 4 and 6 to specific sites suggests distinct novel introductions of HIV and HCV into PWID populations, potentially via drug trafficking routes from neighboring countries where these strains are common.

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.

The population level care cascade for hepatitis C in British Columbia, Canada as of 2018: Impact of direct acting antivirals

BACKGROUND

Population-level monitoring of hepatitis C virus (HCV) infected people across cascades of care identifies gaps in access and engagement in care and treatment. We characterized the population-level care cascade for HCV in British Columbia (BC), Canada before and after introduction of Direct Acting Antiviral (DAA) treatment.

METHODS

BC Hepatitis Testers Cohort (BC-HTC) includes 1.7 million individuals tested for HCV, HIV, reported cases of hepatitis B, and active tuberculosis in BC from 1990 to 2018 linked to medical visits, hospitalizations, cancers, prescription drugs and mortality data. We defined six HCV care cascade stages: (a) antibody diagnosed; (b) RNA tested; (c) RNA positive; (d) genotyped; (e) initiated treatment; and (f) achieved sustained virologic response (SVR).

RESULTS

We estimated 61 127 people were HCV antibody positive in BC in 2018 (undiagnosed: 7686, 13%; diagnosed: 53 441, 87%). Of those diagnosed, 83% (44 507) had HCV RNA testing, and of those RNA positive, 90% (28 716) were genotyped. Of those genotyped, 61% (17 441) received therapy, with 90% (15 672) reaching SVR. Individuals from older birth cohorts had lower progression to HCV RNA testing. While people who currently inject drugs had the highest proportional progression to RNA testing, this group had the lowest proportional treatment uptake.

CONCLUSIONS

Although gaps in HCV RNA and genotype testing after antibody diagnosis exist, the largest gap in the care cascade is treatment initiation, despite introduction of DAA treatment and removal of treatment eligibility restrictions. Further interventions are required to ensure testing and treatment is equitably accessible in BC.

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.

Hepatitis C Core-Antigen Testing from Dried Blood Spots

In order to expand hepatitis C virus (HCV) screening, a change in the diagnostic paradigm is warranted to improve accessibility and decrease costs, such as utilizing dried blood spot (DBS) collection. In our study, blood from 68 patients with chronic HCV infection was spotted onto DBS cards and stored at the following temperatures for one week: −80 °C, 4 °C, 21 °C, 37 °C, and alternating 37 °C and 4 °C; to assess whether temperature change during transportation would affect sensitivity. Sample was eluted from the DBS cards and tested for HCV antibodies (HCV-Ab) and HCV core antigen (core-Ag). HCV-Abs were detected from 68/68 DBS samples at −80 °C, 4 °C, 21 °C, and 67/68 at 37 °C and alternating 37 °C and 4 °C. Sensitivity of core-Ag was as follows: 94% (−80 °C), 94% (4 °C), 91% (21 °C), 93% (37 °C), and 93% (37 °C/4 °C). Not only did temperature not greatly affect sensitivity, but sensitivities are higher than previously reported, and support the use of this assay as an alternative to HCV RNA. We then completed a head-to-head comparison (n = 49) of venous versus capillary samples, and one versus two DBS. No difference in core-Ag sensitivity was observed by sample type, but there was an improvement when using two spots. We conclude that HCV-Abs and core-Ag testing from DBS cards has high diagnostic accuracy and could be considered as an alternative to HCV RNA in certain settings.

Sexually transmitted hepatitis C virus infections: current trends, and recent advances in understanding the spread in men who have sex with men

INTRODUCTION

Hepatitis C virus (HCV) is a major public health threat. Although the recent availability of highly effective directly acting antivirals created optimism towards HCV elimination, there is ongoing transmission of HCV in men who have sex with men (MSM). We here report current epidemiological trends and synthesise evidence on behavioural, network, cellular and molecular host factors associated with sexual transmission of HCV, in particular the role of HIV-1 co-infection. We discuss prevention opportunities focusing on the potential of HCV treatment.

METHODS

We searched MEDLINE, fact sheets from health professional bodies and conference abstracts using appropriate keywords to identify and select relevant reports.

RESULTS AND DISCUSSION

Recent studies strongly suggest that HCV is transmitted via sexual contact in HIV-positive MSM and more recently in HIV-negative MSM eligible for or on pre-exposure prophylaxis. The reinfection risk following clearance is about 10 times the risk of primary infection. International connectedness of MSM transmission networks might contribute to ongoing reinfection. Some of these networks might overlap with networks of people who inject drugs. Although, the precise mechanisms facilitating sexual transmission remain unclear, damage to the mucosal barrier in the rectum could increase susceptibility. Mucosal dendritic cell subsets could increase HCV susceptibility by retaining HCV and transmitting the virus to other cells, allowing egress into blood and liver. Early identification of new HCV infections is important to prevent onward transmission, but early diagnosis of acute HCV infection and prompt treatment is hampered by the slow rate of HCV antibody seroconversion, which in rare cases may take more than a year. Novel tests such as testing for HCV core antigen might facilitate early diagnosis.

CONCLUSIONS

High-risk sexual behaviour, network characteristics, co-infection with sexually transmitted infections like HIV-1 and other concomitant bacterial and viral sexually transmitted infections are important factors that lead to HCV spread. Targeted and combined prevention efforts including effective behavioural interventions and scale-up of HCV testing and treatment are required to halt HCV transmission in MSM.

Clinical Evaluation of a Newly Developed Chemiluminescent Enzyme Immunoassay for Hepatitis C Virus Core Antigen in Japan

An advanced and fully automated chemiluminescent enzyme immunoassay for the hepatitis C virus core antigen (HCVcAg) was recently developed in Japan. We aimed to evaluate its clinical utility. The new Fujirebio assay (Lumipulse Presto HCVcAg [LP-Presto]) was compared with 2 conventional assays (Lumipulse Ortho HCVcAg [LP-Ortho] and Abbott's Architect HCVcAg). Basic assessments of LP-Presto (reproducibility, stability, range of quantitation, and specificity) were performed on 220 frozen sera (83 positive and 137 negative by LP-Ortho) and 206 fresh sera (all negative by LP-Ortho). Correlation analysis was performed and the rates of concordance for each assay were determined. Additionally, the frozen sera of 42 hyperimmunoglobulinemia patients, including 3 unmeasurable by LP-Ortho, were tested by LP-Presto. All the basic assessments of LP-Presto were consistent with the results of LP-Ortho and Architect. The concordance rate between LP-Presto and LP-Ortho for the 220 frozen sera was 99.5% (219/220), and that between LP-Presto and Architect was 99.1% (218/220). LP-Presto (HCVcAg cut-off value; 20 fmol/L) was fully consistent with LP-Ortho (100%), which found 343 sera negative for HCVcAg. All 42 hyperimmunoglobulinemic sera were measurable using LP-Presto. In conclusion, the performance of LP-Presto was rapid and reliable, and nonspecific test results due to hyperimmunoglobulinemia were reduced when LP-Presto was used. Therefore, LP-Presto is a high-quality HCVcAg assay that shows promising applications.