Apolipoprotein B100 is required for hepatitis C infectivity and Mipomersen inhibits hepatitis C

Genome editing of oncogenes with ZFNs and TALENs: caveats in nuclease design

Background

Gene knockout technologies involving programmable nucleases have been used to create knockouts in several applications. Gene editing using Zinc-finger nucleases (ZFNs), Transcription activator like effectors (TALEs) and CRISPR/Cas systems has been used to create changes in the genome in order to make it non-functional. In the present study, we have looked into the possibility of using six fingered CompoZr ZFN pair to target the E6 gene of HPV 16 genome.

Methods

HPV 16^+ve cell lines; SiHa and CaSki were used for experiments. CompoZr ZFNs targeting E6 gene were designed and constructed by Sigma-Aldrich. TALENs targeting E6 and E7 genes were made using TALEN assembly kit. Gene editing was monitored by T7E1 mismatch nuclease and Nuclease resistance assays. Levels of E6 and E7 were further analyzed by RT-PCR, western blot as well as immunoflourescence analyses. To check if there is any interference due to methylation, cell lines were treated with sodium butyrate, and Nocodazole.

Results

Although ZFN editing activity in yeast based MEL-I assay was high, it yielded very low activity in tumor cell lines; only 6% editing in CaSki and negligible activity in SiHa cell lines. Though editing efficiency was better in CaSki, no significant reduction in E6 protein levels was observed in immunocytochemical analysis. Further, in silico analysis of DNA binding prediction revealed that some of the ZFN modules bound to sequence that did not match the target sequence. Hence, alternate ZFN pairs for E6 and E7 were not synthesized since no further active sites could be identified by in silico analyses. Then we designed TALENs to target E6 and E7 gene. TALENs designed to target E7 gene led to reduction of E7 levels in CaSki and SiHa cervical cancer cell lines. However, TALEN designed to target E6 gene did not yield any editing activity.

Conclusions

Our study highlights that designed nucleases intended to obtain bulk effect should have a reasonable editing activity which reflects phenotypically as well. Nucleases with low editing efficiency, intended for generation of knockout cell lines nucleases could be obtained by single cell cloning. This could serve as a criterion for designing ZFNs and TALENs.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0666-0) contains supplementary material, which is available to authorized users.

Exploring lipid and apolipoprotein levels in chronic hepatitis C patients according to their response to antiviral treatment

BACKGROUND

Hepatitis C virus is known to be highly dependent of lipid metabolism to infect new cells and replicate.

AIMS

To investigate lipid and apolipoprotein profile in chronic HCV patients according to treatment response.

METHODS

Patients recruited from the Hepatitis Treatment Center at Niteroi (Brazil) who received interferon (IFN)-based therapies were separated into two groups, those who achieved sustained virological response (SVR) or not (non-SVR). Another group of patients treated with IFN-free direct-acting antiviral (DAA) therapies was followed from before starting the treatment until one year after therapy. Triglycerides, total cholesterol and fractions were determined by colorimetric and/or electrophoresis techniques. Lecithin cholesterol acyltransferase (LCAT) activity and serum levels of apolipoproteins A1, A2, B, C2, C3 and E were assessed by enzymatic and multiplex assays, respectively.

RESULTS

We studied 114 patients, and SVR was reached in 28 (39.4%) patients treated with IFN-therapy and in all (100%) patients who received DAA. Non-SVR patients (n = 43) presented altered liver parameters post-treatment. Levels of total cholesterol, LDL-C, VLDL-C and triglycerides were significant higher in SVR group. In contrast, LCAT activity and HDL-C levels were elevated in non-SVR patients. Only apolipoproteins B, C2 and C3 levels were increased in SVR group. The follow-up of SVR-DAA patients (n = 43) revealed a significant and progressive increase in serum levels of total cholesterol, LDL-C, VLDL-C and triglycerides.

CONCLUSIONS

After a successful treatment, chronic hepatitis C patients experienced a reestablishment of lipid metabolism. Our results suggest that the monitoring of serum lipids could be a practical and routine laboratory tool to be applied during the treatment follow-up.

Host-targeting therapies for hepatitis C virus infection: current developments and future applications

Chronic hepatitis C virus (HCV) infection is a leading cause of chronic liver diseases and hepatocellular carcinoma (HCC) worldwide. In the past few years, anti-HCV therapies have undergone a revolution with the approval of multiple direct-acting antivirals (DAAs), which enable interferon-free treatments with considerable improvement of sustained virologic response in patients. Today, DAAs have become the standard of care for HCV therapy. However, several limitations remain, which include access to therapy, treatment failure in a subset of patients and persistent risk of HCC development following cure in patients with advanced fibrosis. By targeting conserved host proteins involved in the HCV life cycle, host-targeting agents (HTAs) offer opportunities for pan-genotypic antiviral approaches with a high barrier to drug resistance. Moreover, when applied in combination with DAAs, HTAs could improve the management of difficult-to-treat patients by acting through a complementary mechanism of action. In this review, we summarize the different HTAs evaluated in preclinical and clinical development and discuss their potential role for anti-HCV therapies.

Hepatitis C virus and proprotein convertase subtilisin/kexin type 9: a detrimental interaction to increase viral infectivity and disrupt lipid metabolism

From viral binding to the hepatocyte surface to extracellular virion release, the replication cycle of the hepatitis C virus (HCV) intersects at various levels with lipid metabolism; this leads to a derangement of the lipid profile and to increased viral infectivity. Accumulating evidence supports the crucial regulatory role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in lipoprotein metabolism. Notably, a complex interaction between HCV and PCSK9 has been documented. Indeed, either increased or reduced circulating PCSK9 levels have been observed in HCV patients; this discrepancy might be related to several confounders, including HCV genotype, human immunodeficiency virus (HIV) coinfection and the ambiguous HCV‐mediated influence on PCSK9 transcription factors. On the other hand, PCSK9 may itself influence HCV infectivity, inasmuch as the expression of different hepatocyte surface entry proteins and receptors is regulated by PCSK9. The aim of this review is to summarize the current evidence about the complex interaction between HCV and liver lipoprotein metabolism, with a specific focus on PCSK9. The underlying assumption of this review is that the interconnections between HCV and PCSK9 may be central to explain viral infectivity.

Hepatitis C virus-apolipoprotein interactions: molecular mechanisms and clinical impact

INTRODUCTION

Chronic hepatitis C virus (HCV) infection is a leading cause of cirrhosis, hepatocellular carcinoma and liver failure. Moreover, chronic HCV infection is associated with liver steatosis and metabolic disorders. With 130-150 million people chronically infected in the world, HCV infection represents a major public health problem. One hallmark on the virus is its close link with hepatic lipid and lipoprotein metabolism. Areas covered: HCV is associated with lipoprotein components such as apolipoproteins. These interactions play a key role in the viral life cycle, viral persistence and pathogenesis of liver disease. This review introduces first the role of apolipoproteins in lipoprotein metabolism, then highlights the molecular mechanisms of HCV-lipoprotein interactions and finally discusses their clinical impact. Expert commentary: While the study of virus-host interactions has resulted in a improvement of the understanding of the viral life cycle and the development of highly efficient therapies, major challenges remain: access to therapy is limited and an urgently needed HCV vaccine remains still elusive. Furthermore, the pathogenesis of disease biology is still only partially understood. The investigation of HCV-lipoproteins interactions offers new perspectives for novel therapeutic approaches, contribute to HCV vaccine design and understand virus-induced liver disease and cancer.