Alternative splicing of viral transcripts: the dark side of HBV.

Regulation of alternative splicing is one of the most efficient mechanisms to enlarge the proteomic diversity in eukaryotic organisms. Many viruses hijack the splicing machinery following infection to accomplish their replication cycle. Regarding the HBV, numerous reports have described alternative splicing events of the long viral transcript (pregenomic RNA), which also acts as a template for viral genome replication.

Hepatitis B virus X protein enhances the development of liver fibrosis and the expression of genes associated with epithelial-mesenchymal transitions and tumor progenitor cells.

The hepatitis B virus X protein (HBx) has pleiotropic biological effects, which underlies its potential role in cell transformation. However, its involvement in hepatic fibrosis remains unclear. In this study, we wanted to clarify, in vivo, the role of HBx protein in the development of liver fibrosis.

Alteration of splicing factors' expression during liver disease progression: impact on hepatocellular carcinoma outcome.

Purpose: Trans-acting splicing factors (SF) shape the eukaryotic transcriptome by regulating alternative splicing (AS). This process is recurrently modulated in liver cancer suggesting its direct contribution to the course of liver disease. The aim of our study was to investigate the relationship between the regulation of SFs expression and liver damage.

Hepatitis B virus X protein promotes DNA damage propagation through disruption of liver polyploidization and enhances hepatocellular carcinoma initiation.

Hepatitis B virus X protein (HBx) contributes to Hepatitis B virus (HBV)-related liver cancer. However, its impact on hepatocyte proliferation and genomic stability remains elusive. We studied the role of HBx expression on the progression of cell cycle and liver polyploidization during proliferation and liver carcinogenesis.

Modeling hepatitis virus infections and treatment strategies in humanized mice.

Hepatitis viruses cause chronic liver diseases such as fibrosis, cirrhosis and hepatocellular carcinomas that are difficult to treat and constitute a global health problem. Species-specific viral tropism has limited the usefulness of small animal models to study the impact of viral hepatitis. Immunodeficient mice grafted with human hepatocytes are susceptible to hepatitis viruses B, C, D and E (HBV, HCV, HDV and HEV), developing full viral life cycles, and delivering a means to investigate virus-host interactions and antiviral treatments.

Viral Load Affects the Immune Response to HBV in Mice With Humanized Immune System and Liver.

Background & Aims: Hepatitis B virus (HBV) infects hepatocytes, but the mechanisms of the immune response against the virus and how it affects disease progression are unclear.

Methods: We performed studies with BALB/c Rag2Il2rgSirpaAlb-uPA mice, stably engrafted with human hepatocytes (HUHEP) with or without a human immune system (HIS). HUHEP and HIS-HUHEP mice were given an intraperitoneal injection of HBV.

Alternative splicing of hepatitis B virus: A novel virus/host interaction altering liver immunity.

Background & Aims: Hepatitis B virus (HBV) RNA can undergo alternative splicing, but the relevance of this post-transcriptional regulation remains elusive. The mechanism of HBV alternative splicing regulation and its impact on liver pathogenesis were investigated.

Methods: HBV RNA-interacting proteins were identified by RNA pull-down, combined with mass spectrometry analysis.

A novel mouse model for stable engraftment of a human immune system and human hepatocytes.

Hepatic infections by hepatitis B virus (HBV), hepatitis C virus (HCV) and Plasmodium parasites leading to acute or chronic diseases constitute a global health challenge. The species tropism of these hepatotropic pathogens is restricted to chimpanzees and humans, thus model systems to study their pathological mechanisms are severely limited. Although these pathogens infect hepatocytes, disease pathology is intimately related to the degree and quality of the immune response.

Alternative splicing-regulated protein of hepatitis B virus hacks the TNF-α-stimulated signaling pathways and limits the extent of liver inflammation.

Hepatitis B splicing-regulated protein (HBSP) of the hepatitis B virus (HBV) was uncovered a few years ago but its function remains unknown. HBSP expression occurs from a spliced viral transcript that increases during the course of liver disease. This study aimed at characterizing the impact of HBSP on cellular signaling pathways in vitro and on liver pathogenesis in transgenic (Tg) mice.

C-terminal-truncated hepatitis B virus X protein enhances the development of diethylnitrosamine-induced hepatocellular carcinogenesis.

Hepatitis B virus X protein (HBx) is involved in the development of hepatocellular carcinoma (HCC). The HBx sequence is a preferential site of integration into the human genome, leading to the formation of C-terminal-truncated HBx proteins (Ct-HBx). We previously reported that Ct-HBx proteins were able to potentiate cell transformation in vitro.

La protéine X du virus de l'hépatite B et son rôle dans le développement du carcinome hépatocellulaire.

Hepatocellular carcinoma (HCC) is the most frequent form of liver cancer worldwide, and represents the third cause of death. While epidemiological studies have clearly established that hepatitis B virus (HBV) infection is a major risk factor for the development of HCC, the molecular mechanisms underlying virally-induced tumourigenesis are not fully understood. The transcriptional regulatory HBx protein has been described as a multifunctional protein exhibiting numerous activities affecting gene transcription, intracellular signal transduction, cell proliferation, apoptosis and DNA repair.

Regulation of interleukin-6 in head and neck squamous cell carcinoma is related to papillomavirus infection.

The prevalence of head and neck squamous cell carcinoma (HNSCC) related to human papillomavirus (HPV) is increasing, unlike tobacco- and alcohol-associated cancers. To gain a clearer understanding of the molecular mechanisms implicated in HNSCC, depending on the presence or not of a viral sequence, we investigated the expression of proteins detected in the tumor regions of HNSCC patients. Twenty-two untreated HNSCC patients were selected according to the presence of HPV-16.

Hepatitis B virus HBx protein impairs liver regeneration through enhanced expression of IL-6 in transgenic mice.

Background & Aims: Conflicting results have been reported regarding the impact of hepatitis B virus X protein (HBx) expression on liver regeneration triggered by partial hepatectomy (PH). In the present report we investigated the mechanisms by which HBx protein alters hepatocyte proliferation after PH.

Methods: PH was performed on a transgenic mouse model in which HBx expression is under the control of viral regulatory elements and liver regeneration was monitored.

Detection and genotyping of human papillomavirus by real-time PCR assay.

Background: Diagnosis of human papillomavirus (HPV) disease remains a challenge due to several factors related to the cost, the workload of available commercial assays to detect and genotype HPV, and to the low prevalence of infected patients.

Objective: Our study aimed to develop a real-time PCR, based on SPF10 primers, in order to combine HPV-DNA detection and genotype identification avoiding the negative samples.

Study Design: Validation of SYBR-green based SPF10 real-time PCR on HPV-DNA plasmids followed by the investigation of the viral status in 92 samples from oropharyngeal (94%) cutaneous biopsies (3%) and anal smears (3%) which had previously been HPV-genotyped by LiPA hybridization.

Production of hepatitis B defective particles is dependent on liver status.

Defective hepatitis B virus (dHBV) generated from spliced RNA is detected in the sera of HBV-chronic carriers. Our study was designed to determine whether the proportion of dHBV changed during the course of infection, and to investigate whether dHBV might interfere with HBV replication. To achieve this, HBV wild-type and dHBV levels were determined by Q-PCR in sera from 56 untreated chronic patients and 23 acute patients, in sequential samples from 4 treated-patients and from liver-humanized mice after HBV infection.

Antiviral activity of Bay 41-4109 on hepatitis B virus in humanized Alb-uPA/SCID mice.

Current treatments for HBV chronic carriers using interferon alpha or nucleoside analogues are not effective in all patients and may induce the emergence of HBV resistant strains. Bay 41-4109, a member of the heteroaryldihydropyrimidine family, inhibits HBV replication by destabilizing capsid assembly. The aim of this study was to determine the antiviral effect of Bay 41-4109 in a mouse model with humanized liver and the spread of active HBV.

IL-15 transpresentation promotes both human T-cell reconstitution and T-cell-dependent antibody responses in vivo.

Cytokine immunotherapies targeting T lymphocytes are attractive clinical interventions against viruses and tumors. In the mouse, the homeostasis of memory α/β CD8(+) T cells and natural killer (NK) cells is significantly improved with increased IL-15 bioavailability. In contrast, the role of "transpresented" IL-15 on human T-cell development and homeostasis in vivo is unknown.

Inhibition of hepatitis B virus DNA replication by a thermostable interferon-γ variant.

Background: Treatment of HBV chronic carriers using interferon (IFN)-α or nucleoside/nucleotide analogues fails to suppress viral infection. Type-II IFN-γ has been shown to inhibit HBV replication. The goal of the present work was to evaluate the antiviral efficacy against HBV of a thermostable IFN-γ variant isolated using Massive Mutagenesis and thermoresistant selection (THR) technologies.

Role of the hepatitis B virus proteins in pro- and anti-apoptotic processes.

The Hepatitis B virus (HBV) can induces severe liver diseases as chronic hepatitis and hepatocellular carcinoma. Actually, apoptosis can play an important role in the progress of these diseases. As apoptosis goes through various extrinsic or intrinsic pathways, with activation of caspases and the possible involvement of mitochondria, HBV proteins can interfere with the various apoptosis processes.

Hepatitis delta virus proteins repress hepatitis B virus enhancers and activate the alpha/beta interferon-inducible MxA gene.

Co-infection and superinfection of hepatitis B virus (HBV) with hepatitis delta virus (HDV) leads to suppression of HBV replication both in patients and in animal and cellular models. The mechanisms behind this inhibition have not previously been explored fully. HBV replication is governed by four promoters and two enhancers, Enh1 and Enh2.

Humanized mice for modeling human infectious disease: challenges, progress, and outlook.

Over 800 million people worldwide are infected with hepatitis viruses, human immunodeficiency virus (HIV), and malaria, resulting in more than 5 million deaths annually. Here we discuss the potential and challenges of humanized mouse models for developing effective and affordable therapies and vaccines, which are desperately needed to combat these diseases.

Cell therapy for the diseased liver: from stem cell biology to novel models for hepatotropic human pathogens.

It has long been known that hepatocytes possess the potential to replicate through many cell generations because regeneration can be achieved in rodents after serial two-thirds hepatectomy. It has taken considerable time and effort to harness this potential, with liver regeneration models involving hepatocyte transplantation developing over the past 15 years. This review will describe the experiments that have established the models and methodology for liver repopulation, and the use of cells other than adult hepatocytes in liver repopulation, including hepatic cell lines and hematopoietic, cord blood, hepatic and embryonic stem cells.

Rescue of fertility in homozygous mice for the urokinase plasminogen activator transgene by the transplantation of mouse hepatocytes.

Development of the urokinase plasminogen activator/SCID (uPA/SCID) transgenic mouse model has opened new perspectives for the study of different biological mechanisms such as liver regeneration, stem cell differentiation, and human hepatic pathogens. We observed that homozygous uPA/SCID mice (uPA+/+/SCID) had a small offspring, indicating a fertility defect. The goal of this study was thus to rescue the fertility of homozygous uPA mice.

Prospective comparison of Abbott RealTime HBV DNA and Versant HBV DNA 3.0 assays for hepatitis B DNA quantitation: impact on HBV genotype monitoring.

The quantitation of human hepatitis B virus (HBV) in the serum of infected patients is recommended to characterize the course of chronic HBV infection. The aim of this prospective study was to evaluate the performance of the Abbott RealTime PCR assay for HBV DNA quantitation by comparison with the standard Versant HBV DNA 3.0 assay.

Morphogenetic competence of HNF4 alpha-deficient mouse hepatic cells.

Background/aims: To specify roles of HNF 4 alpha in mouse liver development, we have analyzed the ex vivo morphogenetic potential of HNF4 alpha-null embryonic hepatic cells.

Methods: Using mice with floxed or deficiency alleles of HNF4 alpha, hepatic cells lacking this transcription factor were explanted into primary culture and derived into cell lines.

Results: Contrary to behavior in vivo where HNF4 alpha-null liver cells fail to show normal polarity and epithelialization, e18.