Refine
Year of publication
- 2020 (3) (remove)
Document Type
- Article (3)
Language
- English (3)
Has Fulltext
- yes (3)
Is part of the Bibliography
- no (3)
Keywords
Institute
- Medizin (3)
Inhibitors against the NS3-4A protease of hepatitis C virus (HCV) have proven to be useful drugs in the treatment of HCV infection. Although variants have been identified with mutations that confer resistance to these inhibitors, the mutations do not restore replicative fitness and no secondary mutations that rescue fitness have been found. To gain insight into the molecular mechanisms underlying the lack of fitness compensation, we screened known resistance mutations in infectious HCV cell culture with different genomic backgrounds. We observed that the Q41R mutation of NS3-4A efficiently rescues the replicative fitness in cell culture for virus variants containing mutations at NS3-Asp168. To understand how the Q41R mutation rescues activity, we performed protease activity assays complemented by molecular dynamics simulations, which showed that protease-peptide interactions far outside the targeted peptide cleavage sites mediate substrate recognition by NS3-4A and support protease cleavage kinetics. These interactions shed new light on the mechanisms by which NS3-4A cleaves its substrates, viral polyproteins and a prime cellular antiviral adaptor protein, the mitochondrial antiviral signaling protein MAVS. Peptide binding is mediated by an extended hydrogen-bond network in NS3-4A that was effectively optimized for protease-MAVS binding in Asp168 variants with rescued replicative fitness from NS3-Q41R. In the protease harboring NS3-Q41R, the N-terminal cleavage products of MAVS retained high affinity to the active site, rendering the protease susceptible for potential product inhibition. Our findings reveal delicately balanced protease-peptide interactions in viral replication and immune escape that likely restrict the protease adaptive capability and narrow the virus evolutionary space.
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.
Chronic viral hepatitis is associated with substantial morbidity and mortality worldwide. The aim of our study was to assess the ability of point shear‐wave elastography (pSWE) using acoustic radiation force impulse imaging for the prediction of the following liver‐related events (LREs): new diagnosis of HCC, liver transplantation, or liver‐related death (hepatic decompensation was not included as an LRE). pSWE was performed at study inclusion and compared with liver histology, transient elastography (TE), and serologic biomarkers (aspartate aminotransferase to platelet ratio index, Fibrosis‐4, FibroTest). The performance of pSWE and TE to predict LREs was assessed by calculating the area under the receiver operating characteristic curve and a Cox proportional‐hazards regression model. A total of 254 patients with a median follow‐up of 78 months were included in the study. LRE occurred in 28 patients (11%) during follow‐up. In both patients with hepatitis B virus and hepatitis C virus (HCV), pSWE showed significant correlations with noninvasive tests and TE, and median pSWE and TE values were significantly different between patients with LREs and patients without LREs (both P < 0.0001). In patients with HCV, the area under the receiver operating characteristic curve for pSWE and TE to predict LREs were comparable: 0.859 (95% confidence interval [CI], 0.747‐0.969) and 0.852 (95% CI, 0.737‐0.967) (P = 0.93). In Cox regression analysis, pSWE independently predicted LREs in all patients with HCV (hazard ratio, 17.9; 95% CI, 5.21‐61‐17; P < 0.0001) and those who later received direct‐acting antiviral therapy (hazard ratio, 17.11; 95% CI, 3.88‐75.55; P = 0.0002). Conclusion: Our study shows good comparability between pSWE and TE. pSWE is a promising tool for the prediction of LREs in patients with viral hepatitis, particularly those with chronic HCV. Further studies are needed to confirm our data and assess their prognostic value in other liver diseases.