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Although direct-acting antiviral medications effectively cure hepatitis C in most patients, sometimes treatment selects for resistant viruses, causing antiviral drugs to be either ineffective or only partially effective. Multidrug resistance is common in patients for whom DAA treatment fails. Older patients and patients with advanced liver diseases are more likely to select drug-resistant viruses. Collective efforts from international communities and governments are needed to develop an optimal approach to managing drug resistance and preventing the transmission of resistant viruses.
Different highly effective interferon-free treatment options for chronic hepatitis C virus (HCV) infection are currently available. Pre-existence of resistance associated variants (RAVs) to direct antiviral agents (DAAs) reduces sustained virologic response (SVR) rates by 3–53% in hepatitis C virus (HCV) genotype 1 infected patients depending on different predictors and the DAA regimen used. Frequencies of single and combined resistance to NS3, NS5A and NS5B inhibitors and consequences for the applicability of different treatment regimens are unknown. Parallel population based sequencing of HCV NS3, NS5A and NS5B genes in 312 treatment-naïve Caucasian HCV genotype 1 infected patients showed the presence of major resistant variants in 20.5% (NS3), 11.9% (NS5A), and 22.1% (NS5B) with important differences for HCV subtypes. In NS3, Q80K was observed in 34.7% and 2.1% of subtype 1a and 1b patients, respectively while other RAVs to second generation protease inhibitors were detected rarely (1.4%). Within NS5A RAVs were observed in 7.1% of subtype 1a and 17.6% in subtype 1b infected patients. RAVs to non-nucleoside NS5B inhibitors were observed in 3.5% and 44.4% of subtype 1a and 1b patients, respectively. Considering all three DAA targets all subtype 1a and 98.6% of subtype 1b infected patients were wildtype for at least one interferon free DAA regimen currently available. In conclusion, baseline resistance testing allows the selection of at least one RAVs-free treatment option for nearly all patients enabling a potentially cost- and efficacy-optimized treatment of chronic hepatitis C.
Background/Aims: An estimated 80 million people worldwide are infected with viremic hepatitis C virus (HCV). Even after eradication of HCV with direct acting antivirals (DAAs), hepatic fibrosis remains a risk factor for hepatocarcinogenesis. Recently, we confirmed the applicability of microfibrillar-associated protein 4 (MFAP4) as a serum biomarker for the assessment of hepatic fibrosis. The aim of the present study was to assess the usefulness of MFAP4 as a biomarker of liver fibrosis after HCV eliminating therapy with DAAs.
Methods: MFAP4 was measured using an immunoassay in 50 hepatitis C patients at baseline (BL), the end-of-therapy (EoT), and the 12-week follow-up visit (FU). Changes in MFAP4 from BL to FU and their association with laboratory parameters including alanine aminotransferase (ALT), aspartate aminotransferase (AST), platelets, the AST to platelet ratio index (APRI), fibrosis-4 score (FIB-4), and albumin were analyzed.
Results: MFAP4 serum levels were representative of the severity of hepatic fibrosis at BL and correlated well with laboratory parameters, especially APRI (Spearman correlation, R²=0.80). Laboratory parameters decreased significantly from BL to EoT. MFAP4 serum levels were found to decrease from BL and EoT to FU with high statistical significance (Wilcoxon p<0.001 for both).
Conclusions: Our findings indicate that viral eradication resulted in reduced MFAP4 serum levels, presumably representing a decrease in hepatic fibrogenesis or fibrosis. Hence, MFAP4 may be a useful tool for risk assessment in hepatitis C patients with advanced fibrosis after eradication of the virus.
Dual function of the NK cell receptor 2B4 (CD244) in the regulation of HCV-specific CD8+ T cells
(2011)
The outcome of viral infections is dependent on the function of CD8+ T cells which are tightly regulated by costimulatory molecules. The NK cell receptor 2B4 (CD244) is a transmembrane protein belonging to the Ig superfamily which can also be expressed by CD8+ T cells. The aim of this study was to analyze the role of 2B4 as an additional costimulatory receptor regulating CD8+ T cell function and in particular to investigate its implication for exhaustion of hepatitis C virus (HCV)-specific CD8+ T cells during persistent infection. We demonstrate that (i) 2B4 is expressed on virus-specific CD8+ T cells during acute and chronic hepatitis C, (ii) that 2B4 cross-linking can lead to both inhibition and activation of HCV-specific CD8+ T cell function, depending on expression levels of 2B4 and the intracellular adaptor molecule SAP and (iii) that 2B4 stimulation may counteract enhanced proliferation of HCV-specific CD8+ T cells induced by PD1 blockade. We suggest that 2B4 is another important molecule within the network of costimulatory/inhibitory receptors regulating CD8+ T cell function in acute and chronic hepatitis C and that 2B4 expression levels could also be a marker of CD8+ T cell dysfunction. Understanding in more detail how 2B4 exerts its differential effects could have implications for the development of novel immunotherapies of HCV infection aiming to achieve immune control.
The Q80K polymorphism in the NS3-4A protease of the hepatitis C virus is associated with treatment failure of direct-acting antiviral agents. This polymorphism is highly prevalent in genotype 1a infections and stably transmitted between hosts. Here, we investigated the underlying molecular mechanisms of evolutionarily conserved coevolving amino acids in NS3-Q80K and revealed potential implications of epistatic interactions in immune escape and variants persistence. Using purified protein, we characterized the impact of epistatic amino acid substitutions on the physicochemical properties and peptide cleavage kinetics of the NS3-Q80K protease. We found that Q80K destabilized the protease protein fold (p < 0.0001). Although NS3-Q80K showed reduced peptide substrate turnover (p < 0.0002), replicative fitness in an H77S.3 cell culture model of infection was not significantly inferior to the WT virus. Epistatic substitutions at residues 91 and 174 in NS3-Q80K stabilized the protein fold (p < 0.0001) and leveraged the WT protease stability. However, changes in protease stability inversely correlated with enzymatic activity. In infectious cell culture, these secondary substitutions were not associated with a gain of replicative fitness in NS3-Q80K variants. Using molecular dynamics, we observed that the total number of residue contacts in NS3-Q80K mutants correlated with protein folding stability. Changes in the number of contacts reflected the compensatory effect on protein folding instability by epistatic substitutions. In summary, epistatic substitutions in NS3-Q80K contribute to viral fitness by mechanisms not directly related to RNA replication. By compensating for protein-folding instability, epistatic interactions likely protect NS3-Q80K variants from immune cell recognition.
Background: Accurate assessment of hepatic fibrosis in patients with chronic HBeAg-negative Hepatitis B is of crucial importance not only to predict the long-term clinical course, but also to evaluate antiviral therapy indication. The aim of this study was to prospectively assess the utility of point shear wave elastography (pSWE) for longitudinal non-invasive fibrosis assessment in a large cohort of untreated patients with chronic HBeAg-negative hepatitis B virus (HBV) infection.
Methods: 407 consecutive patients with HBeAg-negative HBV infection who underwent pSWE, transient elastography (TE) as well as laboratory fibrosis markers, including fibrosis index based on four factors (FIB-4), aspartate to platelet ratio index (APRI) and FibroTest, on the same day were prospectively followed up for six years. Patients were classified into one of the three groups: inactive carriers (IC; HBV-DNA <2000 IU/mL and ALT <40 U/L); grey zone group 1 (GZ-1; HBV DNA <2000 IU/mL and ALT >40 U/L); grey zone group 2 (GZ-2; HBV-DNA >2000 IU/mL and ALT <40 U/L).
Results: pSWE results were significantly correlated with TE (r = 0.29, p < 0.001) and APRI (r = 0.17; p = 0.005). Median pSWE values did not differ between IC, GZ-1 and GZ-2 patients (p = 0.82, p = 0.17, p = 0.34). During six years of follow-up, median pSWE and TE values did not differ significantly over time (TE: p = 0.27; pSWE: p = 0.05).
Conclusion: Our data indicate that pSWE could be useful for non-invasive fibrosis assessment and follow-up in patients with HBeAg-negative chronic HBV infection.
Protease inhibitors (PIs) are important components of treatment regimens for patients with chronic hepatitis C virus (HCV) infection. However, emergence and persistence of antiviral resistance could reduce their efficacy. Thus, defining resistance determinants is highly relevant for efforts to control HCV. Here, we investigated patterns of PI resistance–associated substitutions (RASs) for the major HCV genotypes and viral determinants for persistence of key RASs. We identified protease position 156 as a RAS hotspot for genotype 1‐4, but not 5 and 6, escape variants by resistance profiling using PIs grazoprevir and paritaprevir in infectious cell culture systems. However, except for genotype 3, engineered 156‐RASs were not maintained. For genotypes 1 and 2, persistence of 156‐RASs depended on genome‐wide substitution networks, co‐selected under continued PI treatment and identified by next‐generation sequencing with substitution linkage and haplotype reconstruction. Persistence of A156T for genotype 1 relied on compensatory substitutions increasing replication and assembly. For genotype 2, initial selection of A156V facilitated transition to 156L, persisting without compensatory substitutions. The developed genotype 1, 2, and 3 variants with persistent 156‐RASs had exceptionally high fitness and resistance to grazoprevir, paritaprevir, glecaprevir, and voxilaprevir. A156T dominated in genotype 1 glecaprevir and voxilaprevir escape variants, and pre‐existing A156T facilitated genotype 1 escape from clinically relevant combination treatments with grazoprevir/elbasvir and glecaprevir/pibrentasvir. In genotype 1 infected patients with treatment failure and 156‐RASs, we observed genome‐wide selection of substitutions under treatment. Conclusion : Comprehensive PI resistance profiling for HCV genotypes 1‐6 revealed 156‐RASs as key determinants of high‐level resistance across clinically relevant PIs. We obtained in vitro proof of concept for persistence of highly fit genotype 1‐3 156‐variants, which might pose a threat to clinically relevant combination treatments.
Triple therapy of chronic hepatitis C virus (HCV) infection with boceprevir (BOC) or telaprevir (TVR) leads to virologic failure in many patients which is often associated with the selection of resistance-associated variants (RAVs). These resistance profiles are of importance for the selection of potential rescue treatment options. In this study, we sequenced baseline NS3 RAVs population-based and investigated the sensitivity of NS3 phenotypes in an HCV replicon assay together with clinical factors for a prediction of treatment response in a cohort of 165 German and Swiss patients treated with a BOC or TVR-based triple therapy. Overall, the prevalence of baseline RAVs was low, although the frequency of RAVs was higher in patients with virologic failure compared to those who achieved a sustained virologic response (SVR) (7% versus 1%, P = 0.06). The occurrence of RAVs was associated with a resistant NS3 quasispecies phenotype (P<0.001), but the sensitivity of phenotypes was not associated with treatment outcome (P = 0.2). The majority of single viral and host predictors of SVR was only weakly associated with treatment response. In multivariate analyses, low AST levels, female sex and an IFNL4 CC genotype were independently associated with SVR. However, a combined analysis of negative predictors revealed a significantly lower overall number of negative predictors in patients with SVR in comparison to individuals with virologic failure (P<0.0001) and the presence of 2 or less negative predictors was indicative for SVR. These results demonstrate that most single baseline viral and host parameters have a weak influence on the response to triple therapy, whereas the overall number of negative predictors has a high predictive value for SVR.
Background & Aims: HBV genotype G (HBV/G) is mainly found in co-infections with other HBV genotypes and was identified as an independent risk factor for liver fibrosis. This study aimed to analyse the prevalence of HBV/G co-infections in healthy European HBV carriers and to characterize the crosstalk of HBV/G with other genotypes.
Methods: A total of 560 European HBV carriers were tested via HBV/G-specific PCR for HBV/G co-infections. Quasispecies distribution was analysed via deep sequencing, and the clinical phenotype was characterized regarding qHBsAg-/HBV-DNA levels and frequent mutations. Replicative capacity and expression of HBsAg/core was studied in hepatoma cells co-expressing HBV/G with either HBV/A, HBV/D or HBV/E using bicistronic vectors.
Results: Although no HBV/G co-infection was found by routine genotyping PCR, HBV/G was detected by specific PCR in 4%-8% of patients infected with either HBV/A or HBV/E but only infrequently in other genotypes. In contrast to HBV/E, HBV/G was found as the quasispecies major variant in co-infections with HBV/A. No differences in the clinical phenotype were observed for HBV/G co-infections. In vitro RNA and DNA levels were comparable among all genotypes, but expression and release of HBsAg was reduced in co-expression of HBV/G with HBV/E. In co-expression with HBV/A and HBV/E expression of HBV/G-specific core was enhanced while core expression from the corresponding genotype was markedly diminished.
Conclusions: HBV/G co-infections are common in European inactive carriers with HBV/A and HBV/E infection, but sufficient detection depends strongly on the assay. HBV/G regulated core expression might play a critical role for survival of HBV/G in co-infections.
Hepatitis C virus (HCV) substantially affects lipid metabolism, and remodeling of sphingolipids appears to be essential for HCV persistence in vitro. The aim of the current study is the evaluation of serum sphingolipid variations during acute HCV infection. We enrolled prospectively 60 consecutive patients with acute HCV infection, most of them already infected with human immunodeficiency virus (HIV), and serum was collected at the time of diagnosis and longitudinally over a six-month period until initiation of antiviral therapy or confirmed spontaneous clearance. Quantification of serum sphingolipids was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Spontaneous clearance was observed in 11 out of 60 patients (18.3%), a sustained viral response (SVR) in 43 out of 45 patients (95.5%) receiving an antiviral treatment after follow-up, whereas persistence of HCV occurred in six out of 60 patients (10%). C24-ceramide (C24-Cer)-levels increased at follow-up in patients with spontaneous HCV eradication (p < 0.01), as compared to baseline. Sphingosine and sphinganine values were significantly upregulated in patients unable to clear HCV over time compared to patients with spontaneous clearance of HCV infection on follow-up (p = 0.013 and 0.006, respectively). In summary, the persistence of HCV after acute infection induces a downregulation of C24Cer and a simultaneous elevation of serum sphingosine and sphinganine concentrations.
Utility of the new cobas HCV test for viral load monitoring during direct-acting antiviral therapy
(2019)
Background: The COBAS AmpliPrep/COBAS TaqMan assay HCV (CAP/CTM) is widely used in clinical routine for HCV testing. Recently, the new cobas HCV test was established for high throughput testing with minimal operator intervention. As different assays may yield different quantitative/qualitative results that possibly impact treatment decisions, the aim of this study was to externally evaluate the cobas HCV test performance in comparison to CAP/CTM in a clinically relevant setting.
Methods: Serum samples were obtained from 270 patients who received direct acting antiviral therapy with different treatment regimens at two study sites (Hannover and Frankfurt) in 2016. Overall, 1545 samples (baseline, on-treatment and follow-up) were tested in parallel by both assays.
Results: The mean difference between cobas HCV and CAP/CTM for the quantification of HCV RNA was 0.008 log10 IU/ml HCV RNA (95% limits of agreement: -0.02–0.036) showing excellent agreement of both assays. With respect to clinical cut offs (HCV RNA detectable vs. target not detected and HCV RNA above the lower limit of quantification (LLOQ) vs. <LLOQ), discordant results were obtained in 9.5% and 4.6%, respectively; the greatest differences were observed during early stages of antiviral therapy (week 1, week 2 and week 4), but none were statistically significant. Overall percent agreement for SVR between cobas HCV and CAP/CTM at the 15 IU/ml cutoff was 99.2% (95%CI 92.7%-100%).
Conclusion: The performance of the new cobas HCV test was comparable to CAP/CTM in a clinical setting representing a large patient population with HCV GT 1 and 3 treated with DAAs.