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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.
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.
Oral presentations Background: We selected peptide ligands for the HIV-1 packaging signal PSI by screening phage displayed peptide libraries. Peptide ligands were optimized by screening spot synthesis peptide membranes. The aim of this study is the functional characterization of these peptide ligands with respect to inhibition of HIV-1 replication. Methods: Phage displayed peptide libraries were screened with PSI-RNA structures. The Trp-rich peptide motifs were optimized for specific binding on spot synthesis peptide membranes. The best binding peptide was expressed intracellularly in fusion with RFP or linked to a protein transduction domain (PTD) for intracellular delivery. The effects on virion production were analyzed using pseudotyped lentiviral particles. Results: After positive and negative selection rounds, phages binding specifically to PSI-RNA were identified by ELISA. Peptide inserts contained conserved motifs of aromatic amino acids known to be implicated in binding of PSI-RNA by the natural Gag ligand. The filter assay identified HKWPWW as the best binding ligand for PSI-RNA, which is delivered into several cell lines by addition of a PTD. Compared to a control peptide, the HKWPWW peptide inhibited HIV-1 replication as deduced from reduced titers of culture supernatants. As HKWPWW also binds to the TAR-RNA like the natural nucleocapsid PSI-RNA ligand, the effect on Tat-TAR inhibition will also be analyzed. Currently T-cell lines are established which stably express HKWPWW as well as a control peptide, which will be infected with HIV-1 to monitor the ability of HKWPWW to inhibit wild type HIV-1 replication. Conclusion: The selection of a peptide ligand for PSI-RNA able to inhibit HIV-1 replication proves the suitability of the phage display technology for the selection of peptides binding to RNA-structures. This enables the indentification of peptides serving as leads to interfere with additional targets in the HIV-1 replication cycle.
Funktionelle Charakterisierung von Peptidliganden für das komplexe HIV-1-RNA-Verpackungssignal PSI
(2008)
Im Laufe der vergangenen Jahre hat die Identifizierung von Peptidleitstrukturen in der Wirkstoffentwicklung zunehmend an Bedeutung gewonnen. Die Phage Display Technologie ist eine Methode, welche zur Selektion von inhibitorischen Peptiden weit verbreitet ist. Prinzipiell eignet sich dieser Ansatz auch für die Suche nach neuen Leitstrukturen für die Therapie der HIV-Infektion, welche in hochspezifische und -regulierte Schritte im HIV-Replikationszyklus eingreifen sollen. Bei der Verpackung viraler RNA in neu entstehende Virionen handelt es sich um einen Prozess, welcher auf der gezielten Erkennung der dreidimensionalen Struktur der PSI-Region am 5'-Ende ungespleißter, viraler RNA durch die NCp7-Domäne des Gagp55-Vorläuferproteins basiert. Darüber hinaus partizipiert das NCp7-Protein noch an der Reversen Transkription der HIV-RNA sowie an der Integration proviraler DNA und spielt somit eine zentrale Rolle im HIV-1 Replikationszyklus. In vorangegangenen Arbeiten konnten wir mittels der Phage Display Technologie Peptidliganden für die HIV-1 PSI-RNA selektieren, welche die PSI-RNA-NCp7-Interaktion hemmten und in Folge dessen die Verpackung viraler RNA verhindern sollten. Die Bindung der identifizierten tryptophanreichen Peptide an die PSI-RNA konnte zwar zum Teil in vitro mit NCp7 kompetitiert werden, jedoch wiesen die Peptide eine relativ geringe Affinität für die PSI-RNA auf. Im Vordergrund der vorliegenden Arbeit stand nach Optimierung der Affinität eine umfassende funktionelle Charakterisierung der Peptide hinsichtlich ihrer antiviralen Aktivität in vitro. Zunächst gelang es mittels Spot-Synthese-Membranen die Affinität der PSI-RNA-bindenden Peptide um etwa das 30-fache zu verbessern. Der KD-Wert des optimierten HKWPWW-Peptids lag bei 1,1 µM für ein Teilelement der PSI-RNA, das allein über Verpackungsaktivitäten verfügt. Die folgende Analyse der Bindungseigenschaften des HKWPWW-Peptids an die PSI-RNA über NMR und Fluoreszenz-Spektroskopie offenbarte, dass das Peptid über die hydrophoben Aminosäuren an eine charakteristische Schleifenregion in der Sekundärstruktur der PSI-RNA bindet, ähnlich wie der natürliche Ligand NCp7. Gestützt auf diese Ergebnisse, wurde im Hauptteil des Projekts untersucht, ob das HKWPWW-Peptid in der Lage ist, die Verpackung viraler RNA in HI-Virionen zu hemmen. Hierfür erfolgte die Etablierung diverser Testsysteme, welche die intrazelluläre Expression des Peptids ermöglichten. Die Expression von HKWPWW in Fusion mit RFP in Pseudoviren-produzierenden Zellen über transiente Transfektion führte in der höchsten getesteten DNA-Konzentration (2,5 µg) zu einer 95%igen Reduktion des infektiösen Titers. Dieser inhibitorische Effekt war spezifisch für lentivirale Pseudoviren, da die Produktion gammaretroviraler Pseudoviren nicht durch die Anwesenheit des Peptids beeinflusst wurde. Mittels einer stabilen HKWPWW-exprimierenden T-Zelllinie gelang es nachzuweisen, dass das Peptid sogar in der Lage ist, replikationskompetentes HIV über einen Zeitraum von fünf Tagen zu hemmen. Die Synthese des HKWPWW-Peptids in Fusion mit einer Proteintransduktionsdomäne ermöglichte die direkte Behandlung von HIV-infizierten Zellen und führte zu einer verminderten Freisetzung infektiöser HI-Viren in die Zellkulturüberstände. Dabei lagen die IC50- und IC90-Werte des HKWPWW-Peptids nach zweimaliger Peptidzugabe bei 5, 7 bzw. 28,6 µM. Eine in der Literatur oftmals beschriebene Beobachtung ist, dass bei einer reinen Hemmung der HIV-Verpackung Viren entstehen, welche keine virale RNA enthalten. Das Phänomen war in Anwesenheit des HKWPWW-Peptids wenig ausgeprägt wie Korrelationen von p24-Antigen-ELISA und die Quantifizierung viraler RNA in Viruspartikeln zeigten. Diese Gegebenheit sowie das Wissen über die mannigfaltigen Funktionen des NCp7-Proteins im HIV-Replikationszyklus ließen vermuten, dass HKWPWW noch zusätzlich andere Schritte im HIV-Replikationszyklus hemmen könnte. Unterstützt wurde diese Annahme dadurch, dass HKWPWW Ähnlichkeiten zu der hydrophoben Plattform von NCp7 aufweist, welche essentiell für die Verpackung viraler RNA sowie die Reverse Transkription ist. Damit in Einklang steht, das neben einer Bindung an die PSI-RNA auch eine schwächere Interaktion des HKWPWW-Peptids mit den viralen TAR- und PBS-Strukturen nachgewiesen werden konnte. Die auch beobachtete Hemmung der frühen HIV-Replikationsschritte durch HKWPWW könnte somit mit einer möglichen Hemmung der Transkription viraler Gene, der Reversen Transkription oder Integration erklärt werden. Jedoch zeigte die elektronenmikroskopische Analyse, dass nicht nur weniger Viren in Anwesenheit des HKWPWW-Peptids entstehen, sondern dass diese zum Teil einen weniger kondensierten Kern aufweisen. Dies kann als ein Anhaltspunkt angesehen werden, dass HKWPWW tatsächlich auch auf der Ebene der RNA-Verpackung bzw. der viralen Partikelentstehung einen hemmenden Effekt ausübt. Somit resultiert die beobachtete antivirale Aktivität des HKWPWW-Peptids vermutlich aus kombinierten inhibitorischen Effekten auf mehreren Ebenen der HIV-Replikation.
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.
Background: Re-treatment in patients with a chronic hepatitis C virus (HCV) infection and a previous failure to direct-acting antiviral (DAA) treatment remains a challenge. Therefore, we investigated the success rate of treatment and re-treatment regimens used at our center from October 2011 to March 2018.
Methods: A retrospective analysis of DAA-based HCV therapies of 1096 patients was conducted. Factors associated with a virological relapse were identified by univariable and multivariable logistic regression, treatment success of the re-treatment regimens was evaluated by an analysis of sustained virological response (SVR) rates in patients with a documented follow-up 12 weeks after the end of treatment.
Results: Of 1096 patients treated with DAA-based regimens, 91 patients (8%) were lost to follow-up, 892 of the remaining 1005 patients (89%) achieved an SVR12. Most patients (65/113, 58%) who experienced a virological relapse received an interferon-based DAA regimen. SVR rates were comparable in special cohorts like liver transplant recipients (53/61, 87%) and people with a human immunodeficiency virus (HIV) coinfection (41/45, 91%). On multivariable analysis, interferon-based DAA therapy was associated with treatment failure (odds ratio 0.111, 95%-confidence interval 0.054–0.218) among others. One hundred seventeen patients with multiple DAA treatment courses were identified, of which 97 patients (83%) experienced a single relapse, but further relapses after two (18/117, 15%) or even three (2/117, 2%) treatment courses were also observed. Eighty-two of 96 (85%) re-treatment attempts with all-oral DAA regimens were successful after an initial treatment failure.
Conclusion: Overall, DAA re-treatments were highly effective in this real-world cohort and only a minority of patients failed more than two treatment courses. Switching to–or addition of–a new drug class seem to be valid options for the re-treatment of patients especially after failure of an interferon-based regimen.
Background: Chronic hepatitis C virus (HCV) infections are causally linked with metabolic comorbidities such as insulin resistance, hepatic steatosis, and dyslipidemia. However, the clinical impact of HCV eradication achieved by direct-acting antivirals (DAAs) on glucose and lipid homeostasis is still controversial. The study aimed to prospectively investigate whether antiviral therapy of HCV with DAAs alters glucose and lipid parameters. Methods: 50 patients with chronic HCV who were treated with DAAs were screened, and 49 were enrolled in the study. Biochemical and virological data, as well as noninvasive liver fibrosis parameters, were prospectively collected at baseline, at the end of treatment (EOT) and 12 and 24 weeks post-treatment. Results: 45 of 46 patients achieved sustained virologic response (SVR). The prevalence of insulin resistance (HOMA-IR) after HCV clearance was significantly lower, compared to baseline (5.3 ± 6.1 to 2.5 ± 1.9, p < 0.001), which is primarily attributable to a significant decrease of fasting insulin levels (18.9 ± 17.3 to 11.7 ± 8.7; p = 0.002). In contrast to that, HCV eradication resulted in a significant increase in cholesterol levels (total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein (HDL-C) levels) and Controlled Attenuated Score (CAP), although BMI did not significantly change over time (p = 0.95). Moreover, HOMA-IR correlated significantly with noninvasive liver fibrosis measurements at baseline und during follow-up (TE: r = 0.45; p = 0.003, pSWE: r = 0.35; p = 0.02, APRI: r = 0.44; p = 0.003, FIB-4: r = 0.41; p < 0.001). Conclusion: Viral eradication following DAA therapy may have beneficial effects on glucose homeostasis, whereas lipid profile seems to be worsened.
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.
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.
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.
