Host-Targeting Antivirals for Treatment of Hepatitis C

Treatment of chronic hepatitis C virus (HCV) infection has been revolutionized during last years with the development of highly potent direct-acting antivirals (DAAs) specifically targeting HCV proteins. DAAs are the current standard of care for patients with chronic hepatitis C, leading to high cure rates. However, some hurdles exist including the high cost of these therapies restricting access to patients, their inability to protect against the risk of developing hepatocellular carcinoma in patients with advanced fibrosis, and emergence of resistant variants resulting in treatment failure. New therapeutic options should be essential to overcome DAAs limitations and improve survival. By targeting host-cell factors involved in HCV life cycle, host-targeting antivirals (HTAs) offer opportunity for promising anti-HCV therapy with low mutational rate and may act in a synergistic manner with DAAs to prevent viral resistance and reduce viral replication. Moreover, HTAs could be effective in difficult-to-cure patients by acting through complementary mechanisms. In this chapter, we will focus on the latest and most relevant studies regarding the host-cell factors required in HCV infection and explored as targets of antiviral therapy, we will also discuss the HTAs evaluated in preclinical and clinical development and their potential role as alternative or complementary therapeutic strategies

Regulatory Role of Ribonucleotide Reductase Subunit M2 in Hepatocyte Growth and Pathogenesis of Hepatitis C Virus

Hepatitis C virus (HCV) frequently causes chronic infection in the human liver, which may progress to advanced hepatic fibrosis, cirrhosis, and hepatocellular carcinoma. HCV primarily infects highly differentiated quiescent hepatocytes and can modulate cell cycle-regulatory genes and proliferation pathways, which ultimately contribute to persistent infection and pathogenesis. On the other hand, several studies have shown differential regulation of HCV RNA and viral protein expression levels, depending on the proliferation state of hepatocytes and the phase of the cell cycle. HCV typically requires factors provided by host cells for efficient and persistent viral replication. Previously, we found that HCV infection upregulates the expression of ribonucleotide reductase subunit M2 (RRM2) in quiescent hepatocytes. RRM2 is a rate-limiting protein that catalyzes de novo synthesis of deoxyribonucleotide triphosphates, and its expression is highly regulated during various phases of the cell cycle. RRM2 functions as a pro-viral factor essential for HCV RNA synthesis, but its functional role in HCV-induced liver diseases remains unknown. Here, we present a comprehensive review of the role of the hepatocyte cell cycle, in correlation with RRM2 expression, in the regulation of HCV replication. We also discuss the potential relevance of this protein in the pathogenesis of HCV, particularly in the development of hepatocellular carcinoma

Development of short hairpin RNA expression vectors targeting the internal ribosomal entry site of the classical swine fever virus genomic RNA

Abstract Background Classical swine fever (CSF) is a fatal contagious disease affecting pigs caused by classical swine fever virus (CSFV). The disease can be transmitted by pigs and wild boars, and it is difficult to prevent and control. To obtain necessary information to establish the CSFV resistant animals in a future study, we designed lentiviral vector-delivered short hairpin RNAs (shRNAs) targeting the conserved domain III of the internal ribosomal entry site (IRES) of the CSFV genomic RNA. Results First, we confirmed the effects of siRNAs on CSFV-IRES activity. We observed significant inhibition of CSFV-IRES activity by si42 (domain IIIa), si107 (domain IIIc), and si198 (domain IIIf) in SK-L cells and si56 (domain IIIb), si142 (domain IIId1) and si198 in HEK293 cells without affecting the amount of luciferase RNA. Next, we constructed lentiviral vectors expressing shRNA based on siRNA sequences. Treatment with shRNA-expressing lentivirus was examined at 7 and 14 days post infection in SK-L cells and HEK293 cells, and CSFV-IRES was significantly suppressed at 14 days (sh42) post infection in HEK293 cells without significant cytotoxicity. Next, we examined the silencing effect of siRNA on CSFV replicon RNA and observed a significant effect by si198 after 2 days of treatment and by shRNA-expressing lentivirus (sh56, sh142, and sh198) infection after 14 days of treatment. Treatment of sh198-expressing lentivirus significantly suppressed CSFV infection at 3 days after infection. Conclusion The IRES targeting sh198 expressing lentivirus vector can be a candidate tool for CSFV infection control

Des effecteurs immunitaires polymorphes communs contre les hépatites B et C modulent la sensibilité à l'infection et la clairance spontanée dans une population marocaine

International audienceChronic diseases caused by hepatitis B and C viruses may evolve towards major complications as liver cirrhosis and cancer. Fortunately, only subsets among acutely infected individuals develop a persistent disease suggesting that genetic susceptibility may influence the establishment of chronicity. In the present study we aim to explore variants distribution in genes encoding for important immune response effectors in chronic hepatitis B and C. We intend to identify common features and to establish connections between single nucleotide polymorphisms (SNPs) predisposing to both chronic hepatitis and spontaneous clearance in a Moroccan population. Ten SNPs mapping on seven candidate genes (CD209, TGFβ-1, CCR5, CCL2, CXCL12, SUMO1 and UBC9) were studied in 544 Moroccan subjects grouped in chronically infected patients, spontaneously resolved individuals, liver disease progressors and healthy controls. Among significant associations found between virus infections and genetic variants, we report for the first time an association of rs4804803 (CD209) A and G variants with susceptibility to HBV infection and spontaneous clearance (p<0.001, OR=3.53, 95% CI 2.155; 5.908, and p<0.001, OR=7.75, 95% CI 4.646-13.114, respectively). Other important, albeit previously unknown, association was found between SUMO1 rs10185956T variant and spontaneous clearance of HCV infection (p=0.002, OR=2.71, 95% CI 1.332-5.869). Our observation, that deserves further confirmation with other SNPs and populations, underlines the involvement of selected immune polymorphisms, among which those in CD209, in the natural history of both chronic hepatitis B and C

Non-primate hepacivirus transmission and prevalence: Novel findings of virus circulation in horses and dogs in Morocco

International audienceNon-primate hepacivirus (NPHV) is a homolog of hepatitis C virus and has been isolated from dogs and horses. Data on NPHV prevalence and distribution are not complete, and there is a particular lack of reports from the African continent. The present study represents the first investigation of NPHV prevalence in horses and dogs in North Africa.Blood was collected from 172 horses and 36 dogs at different locations in Morocco, and screened for NPHV RNA using nested PCR targeting 5’UTR and NS3 regions and analyzed for anti-NPHV NS3 antibody using a Gaussia luciferase immunoprecipitation system—to determine seroprevalence. Eight sequences of the NS3 region isolated from positive serum samples were targeted for phylogenetic analysis.Horses and dogs showed respective NPHV RNA positivity rates of 10.5% and 5.5%, and seroprevalences of 65.7% and 8.33%. Juvenile horses appeared more susceptible to infection, with a 23.5% NHPV RNA positivity rate. Seropositivity was more extensive in mares than stallions (77.14% vs. 46.27%, p < 0.0001). Phylogenetically, that NPHV NS3 genes isolated from horses and dog are clustered together. The NPHV strains we detected showed no correlation with geographic location within Morocco.In conclusion, Moroccan horses showed much evidence of previous and/or current NPHV infection, with young age and female sex as noted potential risk factors. Interestingly, NPHV is circulating in dogs as well as horses, suggesting that it has crossed species barriers and that horses and dogs are potential vectors by which an ancestor to hepatitis C virus was transmitted into human populations

Oxidative Stress and Immune Responses During Hepatitis C Virus Infection in Tupaia belangeri

Abstract Hepatitis C virus (HCV) is a leading cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma. To address the molecular basis of HCV pathogenesis using tupaias (Tupaia belangeri), we characterized host responses upon HCV infection. Adult tupaias were infected with HCV genotypes 1a, 1b, 2a, or 4a. Viral RNA, alanine aminotransferase, anti-HCV core and anti-nonstructural protein NS3 antibody titres, reactive oxygen species (ROS), and anti-3β-hydroxysterol-Δ24reductase (DHCR24) antibody levels were measured at 2-week intervals from 0 to 41 weeks postinfection. All HCV genotypes established infections and showed intermittent HCV propagation. Moreover, all tupaias produced anti-core and anti-NS3 antibodies. ROS levels in sera and livers were significantly increased, resulting in induction of DHCR24 antibody production. Similarly, lymphocytic infiltration, disturbance of hepatic cords, and initiation of fibrosis were observed in livers from HCV-infected tupaias. Intrahepatic levels of Toll-like receptors 3, 7, and 8 were significantly increased in all HCV-infected tupaias. However, interferon-β was only significantly upregulated in HCV1a- and HCV2a-infected tupaias, accompanied by downregulation of sodium taurocholate cotransporting polypeptide. Thus, our findings showed that humoral and innate immune responses to HCV infection, ROS induction, and subsequent increases in DHCR24 auto-antibody production occurred in our tupaia model, providing novel insights into understanding HCV pathogenesis

Le blocage de la neddylation provoque un effet antiviral contre la réplication du virus de l'hépatite B

International audienceBackgroundHepatitis B Virus (HBV) is the most common cause of chronic liver disease worldwide. The mechanisms that regulate HBV viral replication remain poorly defined. Here, we show that blocking of the neddylation elicits antiviral effect against HBV replication, indicating that NEDD8 supports viral production.Methods and resultsTo explore role of neddylation, HBV-replicating HepG2.2.15.7 cells and HBV-infected HepG2-hNTCP-30 cells were treated with siNEDD8 and MLN4924, a potent and selective NEDD8-activating enzyme inhibitor. Cell viability, intracellular and extracellular HBV DNA, covalently closed circular DNA (cccDNA), HBsAg, HBeAg, and HBcrAg were measured to assess the consequences of the various treatments on viral replication. Our data showed that HBV infection increased NEDD8 expression in human liver cell lines. Symmetrically, NEDD8 knockdown by siRNA or MLN4924 treatments decreased HBV replication in HepG2.2.15.7 and HepG2-hNTCP-30 cells. Notably, HBsAg, and HBeAg secretions were strongly suppressed in the culture supernatants, but not the HBcrAg. These results indicate that the suppression of NEDD8 decreases HBV replication. However, cccDNA steady level confirms once again its persistence and longevity in chronic infection.ConclusionThe manipulation of the neddylation pathway can thus provide new tools interfering with HBV persistence as well as novel therapeutic strategies against chronic hepatitis B