Time filter

Source Type

Riviere L.,Institute Pasteur Paris | Riviere L.,French National Center for Scientific Research | Gerossier L.,University of Lyon | Ducroux A.,Institute Pasteur Paris | And 10 more authors.
Journal of Hepatology | Year: 2015

Background & Aims Maintenance of the covalently closed circular HBV DNA (cccDNA) that serves as a template for HBV transcription is responsible for the failure of antiviral therapies. While studies in chronic hepatitis patients have shown that high viremia correlates with hyperacetylation of cccDNA-associated histones, the molecular mechanisms controlling cccDNA stability and transcriptional regulation are still poorly understood. This study aimed to decipher the role of chromatin and chromatin modifier proteins on HBV transcription. Methods We analyzed the chromatin structure of actively transcribed or silenced cccDNA by infecting primary human hepatocytes and differentiated HepaRG cells with wild-type virus or virus deficient (HBVX-) for the expression of hepatitis B virus X protein (HBx), that is required for HBV expression. Results In the absence of HBx, HBV cccDNA was transcriptionally silenced with the concomitant decrease of histone 3 (H3) acetylation and H3K4me3, increase of H3 di- and tri-methylation (H3K9me) and the recruitment of heterochromatin protein 1 factors (HP1) that correlate with condensed chromatin. SETDB1 was found to be the main histone methyltransferase responsible for the deposition of H3K9me3 and HBV repression. Finally, full transcriptional reactivation of HBVX- upon HBx re-expression correlated with an increase of histone acetylation and H3K4me3, and a concomitant decrease of HP1 binding and of H3K9me3 on the cccDNA. Conclusion Upon HBV infection, cellular mechanisms involving SETDB1-mediated H3K9me3 and HP1 induce silencing of HBV cccDNA transcription through modulation of chromatin structure. HBx is able to relieve this repression and allow the establishment of active chromatin. © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.


Pfaender S.,Institute for Experimental Virology | Cavalleri J.M.V.,University of Veterinary Medicine Hannover | Walter S.,Institute for Experimental Virology | Doerrbecker J.,Institute for Experimental Virology | And 13 more authors.
Hepatology | Year: 2015

Hepatitis C virus (HCV) has a very narrow species and tissue tropism and efficiently replicates only in humans and the chimpanzee. Recently, several studies identified close relatives to HCV in different animal species. Among these novel viruses, the nonprimate hepaciviruses (NPHV) that infect horses are the closest relatives of HCV described to date. In this study, we analyzed the NPHV prevalence in northern Germany and characterized the clinical course of infection and viral tissue tropism to explore the relevance of HCV-related horse viruses as a model for HCV infection. We found that approximately 31.4% of 433 horses were seropositive for antibodies (Abs) against NPHV and approximately 2.5% carried viral RNA. Liver function analyses revealed no indication for hepatic impairment in 7 of 11 horses. However, serum gamma-glutamyl transferase (GGT) concentrations were mildly elevated in 3 horses, and 1 horse displayed even highly elevated GGT levels. Furthermore, we observed that NPHV infection could be cleared in individual horses with a simultaneous emergence of nonstructural (NS)3-specific Abs and transient elevation of serum levels of liver-specific enzymes indicative for a hepatic inflammation. In other individual horses, chronic infections could be observed with the copresence of viral RNA and NS3-specific Abs for over 6 months. For the determination of viral tissue tropism, we analyzed different organs and tissues of 1 NPHV-positive horse using quantitative real-time polymerase chain reaction and fluorescent in situ hydridization and detected NPHV RNA mainly in the liver and at lower amounts in other organs. Conclusion: Similar to HCV infections in humans, this work demonstrates acute and chronic stages of NPHV infection in horses with viral RNA detectable predominantly within the liver. © 2014 by the American Association for the Study of Liver Diseases.


Pfaender S.,Institute for Experimental Virology | Heyden J.,Institute for Experimental Virology | Friesland M.,Institute for Experimental Virology | Ciesek S.,Hannover Medical School | And 10 more authors.
Journal of Infectious Diseases | Year: 2013

Background. Hepatitis C virus (HCV) is spread through direct contact with blood, although alternative routes of transmission may contribute to the global burden. Perinatal infection occurs in up to 5% of HCV-infected mothers, and presence of HCV RNA in breast milk has been reported. We investigated the influence of breast milk on HCV infectiousness. Methods/Results. Human breast milk reduced HCV infectivity in a dose-dependent manner. This effect was species-specific because milk from various animals did not inhibit HCV infection. Treatment of HCV with human breast milk did not compromise integrity of viral RNA or capsids but destroyed the lipid envelope. Fractionation of breast milk revealed that the antiviral activity is present in the cream fraction containing the fat. Proteolytic digestion of milk proteins had no influence on its antiviral activity, whereas prolonged storage at 4°C increased antiviral activity. Notably, pretreatment with a lipase inhibitor ablated the antiviral activity and specific free fatty acids of breast milk were antiviral. Conclusions. The antiviral activity of breast milk is linked to endogenous lipase-dependent generation of free fatty acids, which destroy the viral lipid envelope. Therefore, nursing by HCV-positive mothers is unlikely to play a major role in vertical transmission. © The Author 2013.


PubMed | Ghent University, Institute for Experimental Virology, Rockefeller University, Princeton University and Hannover Medical School
Type: Journal Article | Journal: mBio | Year: 2016

Hepatitis C virus (HCV) species tropism is incompletely understood. We have previously shown that at the level of entry, human CD81 and occludin (OCLN) comprise the minimal set of human factors needed for viral uptake into murine cells. As an alternative approach to genetic humanization, species barriers can be overcome by adapting HCV to use the murine orthologues of these entry factors. We previously generated a murine tropic HCV (mtHCV or Jc1/mCD81) strain harboring three mutations within the viral envelope proteins that allowed productive entry into mouse cell lines. In this study, we aimed to characterize the ability of mtHCV to enter and infect mouse hepatocytes in vivo and in vitro Using a highly sensitive, Cre-activatable reporter, we demonstrate that mtHCV can enter mouse hepatocytes in vivo in the absence of any human cofactors. Viral entry still relied on expression of mouse CD81 and SCARB1 and was more efficient when mouse CD81 and OCLN were overexpressed. HCV entry could be significantly reduced in the presence of anti-HCV E2 specific antibodies, suggesting that uptake of mtHCV is dependent on viral glycoproteins. Despite mtHCVs ability to enter murine hepatocytes in vivo, we did not observe persistent infection, even in animals with severely blunted type I and III interferon signaling and impaired adaptive immune responses. Altogether, these results establish proof of concept that the barriers limiting HCV species tropism can be overcome by viral adaptation. However, additional viral adaptations will likely be needed to increase the robustness of a murine model system for hepatitis C.At least 150 million individuals are chronically infected with HCV and are at risk of developing serious liver disease. Despite the advent of effective antiviral therapy, the frequency of chronic carriers has only marginally decreased. A major roadblock in developing a vaccine that would prevent transmission is the scarcity of animal models that are susceptible to HCV infection. It is poorly understood why HCV infects only humans and chimpanzees. To develop an animal model for hepatitis C, previous efforts focused on modifying the host environment of mice, for example, to render them more susceptible to HCV infection. Here, we attempted a complementary approach in which a laboratory-derived HCV variant was tested for its ability to infect mice. We demonstrate that this engineered HCV strain can enter mouse liver cells but does not replicate efficiently. Thus, additional adaptations are likely needed to construct a robust animal model for HCV.


PubMed | University of Veterinary Medicine Hannover and Institute for Experimental Virology
Type: Journal Article | Journal: Veterinary research | Year: 2016

The recently discovered nonprimate hepacivirus (NPHV) naturally infects horses and is the closest known homolog of hepatitis C virus to date. Within a follow-up study acute field infections were monitored in four young Thoroughbred horses until the ages of 12-13months. Serum samples were analyzed for the presence of NPHV RNA and anti-NPHV NS3 antibodies and liver specific parameters were evaluated. The four young horses were not able to clear infection, but remained chronically infected for the entire monitored time period despite the presence of NPHV specific antibodies.


PubMed | University of Veterinary Medicine Hannover, Institute for Experimental Virology and University of Hamburg
Type: | Journal: Veterinary microbiology | Year: 2015

Novel viruses belonging to the genera Hepacivirus and Pegivirus have recently been discovered in horses and other animal species. Viral genomes of non-primate hepaciviruses (NPHV), equine pegivirus 1 (EPgV 1) and Theilers disease associated virus (TDAV) were detected in a horse serum routinely used for cell culture propagation in our laboratory. Therefore, a study was carried out to further investigate the presence of these human Hepatitis C virus (HCV) related viruses in equine serum based products used in veterinary medicine and for research and to characterize the viral genomes. Without exception all commercially available equine sera purchased for cell culture propagation (n=6) were tested positive for NPHV, EPgV 1 or TDAV genomes by qRT-PCR. Molecular analyses of one single commercial horse serum from Europe confirmed multiple viral genomes, including two TDAV genomes significantly different from the only published TDAV sequence. Furthermore, multiple batches of horse serum pools (n=35) collected for manufacturing of biological products turned out to be positive for NPHV and EPgV 1 genomes. Nevertheless, the final commercial products (n=9) were exclusively tested qRT-PCR negative. Field samples (n=119) obtained from two premises located in the same region as the donor horses were analyzed, demonstrating the frequent presence of NPHV and EPgV 1, but the absence of TDAV genomes. The presence of NPHV, EPgV 1 and TDAV in commercial equine sera and serum based products could have considerable consequences for biosecurity and may also bias the outcome of research studies conducted with related viruses.


Pfaender S.,Institute for Experimental Virology | Pfaender S.,Helmholtz Center for Infection Research | Pfaender S.,University of Bern | Pfaender S.,Institute of Virology and Immunology | And 11 more authors.
PLoS Pathogens | Year: 2016

Hepatitis C virus (HCV) induces interferon (IFN) stimulated genes in the liver despite of distinct innate immune evasion mechanisms, suggesting that beyond HCV infected cells other cell types contribute to innate immune activation. Upon coculture with HCV replicating cells, human CD141+ myeloid dendritic cells (DC) produce type III IFN, whereas plasmacytoid dendritic cells (pDC) mount type I IFN responses. Due to limitations in the genetic manipulation of primary human DCs, we explored HCV mediated stimulation of murine DC subsets. Coculture of HCV RNA transfected human or murine hepatoma cells with murine bone marrow-derived DC cultures revealed that only Flt3-L DC cultures, but not GM-CSF DC cultures responded with IFN production. Cells transfected with full length or subgenomic viral RNA stimulated IFN release indicating that infectious virus particle formation is not essential in this process. Use of differentiated DC from mice with genetic lesions in innate immune signalling showed that IFN secretion by HCV-stimulated murine DC was independent of MyD88 and CARDIF, but dependent on TRIF and IFNAR signalling. Separating Flt3-L DC cultures into pDC and conventional CD11b-like and CD8α-like DC revealed that the CD8α-like DC, homologous to the human CD141+ DC, release interferon upon stimulation by HCV replicating cells. In contrast, the other cell types and in particular the pDC did not. Injection of human HCV subgenomic replicon cells into IFN-β reporter mice confirmed the interferon induction upon HCV replication in vivo. These results indicate that HCV-replicating cells stimulate IFN secretion from murine CD8α-like DC independent of infectious virus production. Thus, this work defines basic principles of viral recognition by murine DC populations. Moreover, this model should be useful to explore the interaction between dendritic cells during HCV replication and to define how viral signatures are delivered to and recognized by immune cells to trigger IFN release. © 2016 Pfaender et al.


PubMed | Institute for Experimental Virology, Helmholtz Center for Infection Research and Hannover Medical School
Type: | Journal: Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology | Year: 2016

HCV is transmitted mainly by parenteral routes. However, unprotected anal intercourse has also been identified as a risk factor for HCV infection. HCV RNA can be detected in blood, saliva, and bile, but the presence of HCV in stool has not been investigated yet.Therefore, stool samples of 98 patients were collected prospectively. Specific HCV primers were used to identify samples positive for HCV RNA. HCV RNA-positive samples were tested for HCVcoreAg with the Architect HCVAg assay (Abbott). Presence of occult blood was investigated by the hemoCARE guajak test. Viral stability and infectivity of recombinant HCV particles was investigated in vitro by incubation of genotype 2a chimeric virus Jc1 with bile and stool suspensions.HCV RNA could be detected in 68 out of 98 stool samples from patients with chronic hepatitis C and 16 samples also tested positive for HCVcoreAg. Presence of HCV RNA in stool was more frequent in male than in female and in patients with low platelet counts but was not associated with the detection of occult blood. Stool suspensions and to a lesser extent bile reduced the in vitro infectivity of genotype 2a chimeric Jc1 virus even though infection of Huh7 cells was not completely abrogated.In summary, this study shows for the first time that HCV can frequently be detected in stool samples of chronically infected patients irrespective of occult bleeding. We suggest that stool can be a potential source for HCV infection and thus unprotected anal intercourse should be avoided.


PubMed | Helmholtz Center for Infection Research
Type: | Journal: Journal of virology | Year: 2016

Chronic hepatitis C virus (HCV) infection causes severe liver disease and affects ca. 146 million individuals. Novel directly acting antivirals targeting HCV have revolutionized treatment. However, high costs limits access to therapy. Recently, several related drugs used in humans to treat allergies or as neuroleptics emerged as potent HCV cell entry inhibitors. Insights into their antiviral mode of action may access opportunities for drug repurposing in hepatitis C and possibly other important human viral infections.

Loading Institute for Experimental Virology collaborators
Loading Institute for Experimental Virology collaborators