RESUMEN
Assembly of infectious hepatitis C virus (HCV) particles requires multiple cellular proteins including for instance apolipoprotein E (ApoE). To describe these protein-protein interactions, we performed an affinity purification mass spectrometry screen of HCV-infected cells. We used functional viral constructs with epitope-tagged envelope protein 2 (E2), protein (p) 7, or nonstructural protein 4B (NS4B) as well as cells expressing a tagged variant of ApoE. We also evaluated assembly stage-dependent remodeling of protein complexes by using viral mutants carrying point mutations abrogating particle production at distinct steps of the HCV particle production cascade. Five ApoE binding proteins, 12 p7 binders, 7 primary E2 interactors, and 24 proteins interacting with NS4B were detected. Cell-derived PREB, STT3B, and SPCS2 as well as viral NS2 interacted with both p7 and E2. Only GTF3C3 interacted with E2 and NS4B, highlighting that HCV assembly and replication complexes exhibit largely distinct interactomes. An HCV core protein mutation, preventing core protein decoration of lipid droplets, profoundly altered the E2 interactome. In cells replicating this mutant, E2 interactions with HSPA5, STT3A/B, RAD23A/B, and ZNF860 were significantly enhanced, suggesting that E2 protein interactions partly depend on core protein functions. Bioinformatic and functional studies including STRING network analyses, RNA interference, and ectopic expression support a role of Rad23A and Rad23B in facilitating HCV infectious virus production. Both Rad23A and Rad23B are involved in the endoplasmic reticulum (ER)-associated protein degradation (ERAD). Collectively, our results provide a map of host proteins interacting with HCV assembly proteins, and they give evidence for the involvement of ER protein folding machineries and the ERAD pathway in the late stages of the HCV replication cycle.IMPORTANCEHepatitis C virus (HCV) establishes chronic infections in the majority of exposed individuals. This capacity likely depends on viral immune evasion strategies. One feature likely contributing to persistence is the formation of so-called lipo-viro particles. These peculiar virions consist of viral structural proteins and cellular lipids and lipoproteins, the latter of which aid in viral attachment and cell entry and likely antibody escape. To learn about how lipo-viro particles are coined, here, we provide a comprehensive overview of protein-protein interactions in virus-producing cells. We identify numerous novel and specific HCV E2, p7, and cellular apolipoprotein E-interacting proteins. Pathway analyses of these interactors show that proteins participating in processes such as endoplasmic reticulum (ER) protein folding, ER-associated protein degradation, and glycosylation are heavily engaged in virus production. Moreover, we find that the proteome of HCV replication sites is distinct from the assembly proteome, suggesting that transport process likely shuttles viral RNA to assembly sites.
Asunto(s)
Hepacivirus , Hepatitis C , Humanos , Hepacivirus/genética , Proteínas no Estructurales Virales/genética , Proteoma/metabolismo , Línea Celular , Apolipoproteínas E/metabolismo , Apolipoproteínas/metabolismo , Proteínas de Unión al ADN/metabolismo , Enzimas Reparadoras del ADN/metabolismoRESUMEN
The incidence of hepatitis C virus (HCV) infections remains high even more than 10 years after approval of the first direct-acting antivirals for treatment of hepatitis C. In some countries, more people are newly infected with the virus than patients cured by antiviral therapy. The development of a prophylactic vaccine could prevent virus transmission and thereby make a significant contribution to control the global burden of this disease. In this article, we review the unique challenges and current approaches to HCV vaccine development.HCV is a highly diverse and versatile virus that mostly escapes the immune system and establishes chronic infections. However, up to one third of the exposed individuals can spontaneously resolve HCV infections, which indicates that protective immunity can be achieved. Numerous studies on determinants of protective immunity against HCV show an increasingly complete picture of what a vaccine must achieve. It is very likely that both strong neutralizing antibodies and powerful cytotoxic T cells are needed to reliably protect against chronic HCV infection. The key question is which approaches allow maturation of particularly broadly effective antibodies and T cells. This will be necessary to protect against the high number of different HCV variants. The recent successes of mRNA vaccines open new doors for HCV vaccine research and development. Combined with a deeper understanding of the structure and function of the viral envelope proteins, the identification of cross-protective antibody and Tcell epitopes as well as the use of standardized methods to quantify the effectiveness of vaccine candidates, new perspectives arise for the development of a vaccine.
Asunto(s)
Hepatitis C Crónica , Hepatitis C , Vacunas contra Hepatitis Viral , Vacunas Virales , Antivirales , Alemania , Hepacivirus/genética , Hepatitis C/prevención & control , Anticuerpos contra la Hepatitis C , HumanosRESUMEN
The high genetic diversity of hepatitis C virus (HCV) complicates effective vaccine development. We screened a cohort of 435 HCV-infected individuals and found that 2%-5% demonstrated outstanding HCV-neutralizing activity. From four of these patients, we isolated 310 HCV antibodies, including neutralizing antibodies with exceptional breadth and potency. High neutralizing activity was enabled by the use of the VH1-69 heavy-chain gene segment, somatic mutations within CDRH1, and CDRH2 hydrophobicity. Structural and mutational analyses revealed an important role for mutations replacing the serines at positions 30 and 31, as well as the presence of neutral and hydrophobic residues at the tip of the CDRH3. Based on these characteristics, we computationally created a de novo antibody with a fully synthetic VH1-69 heavy chain that efficiently neutralized multiple HCV genotypes. Our findings provide a deep understanding of the generation of broadly HCV-neutralizing antibodies that can guide the design of effective vaccine candidates.
Asunto(s)
Anticuerpos ampliamente neutralizantes/genética , Hepacivirus/inmunología , Anticuerpos contra la Hepatitis C/genética , Linfocitos B/inmunología , Anticuerpos ampliamente neutralizantes/química , Anticuerpos ampliamente neutralizantes/inmunología , Regiones Determinantes de Complementariedad/química , Regiones Determinantes de Complementariedad/genética , Regiones Determinantes de Complementariedad/inmunología , Epítopos , Femenino , Genotipo , Hepacivirus/genética , Hepatitis C/inmunología , Anticuerpos contra la Hepatitis C/química , Anticuerpos contra la Hepatitis C/inmunología , Humanos , Cadenas Pesadas de Inmunoglobulina/química , Cadenas Pesadas de Inmunoglobulina/genética , Cadenas Pesadas de Inmunoglobulina/inmunología , Masculino , Persona de Mediana Edad , Mutación , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/inmunologíaRESUMEN
OBJECTIVE: Neutralising antibodies are key effectors of infection-induced and vaccine-induced immunity. Quantification of antibodies' breadth and potency is critical for understanding the mechanisms of protection and for prioritisation of vaccines. Here, we used a unique collection of human specimens and HCV strains to develop HCV reference viruses for quantification of neutralising antibodies, and to investigate viral functional diversity. DESIGN: We profiled neutralisation potency of polyclonal immunoglobulins from 104 patients infected with HCV genotype (GT) 1-6 across 13 HCV strains representing five viral GTs. Using metric multidimensional scaling, we plotted HCV neutralisation onto neutralisation maps. We employed K-means clustering to guide virus clustering and selecting representative strains. RESULTS: Viruses differed greatly in neutralisation sensitivity, with J6 (GT2a) being most resistant and SA13 (GT5a) being most sensitive. They mapped to six distinct neutralisation clusters, in part composed of viruses from different GTs. There was no correlation between viral neutralisation and genetic distance, indicating functional neutralisation clustering differs from sequence-based clustering. Calibrating reference viruses representing these clusters against purified antibodies from 496 patients infected by GT1 to GT6 viruses readily identified individuals with extraordinary potent and broadly neutralising antibodies. It revealed comparable antibody cross-neutralisation and diversity between specimens from diverse viral GTs, confirming well-balanced reporting of HCV cross-neutralisation across highly diverse human samples. CONCLUSION: Representative isolates from six neutralisation clusters broadly reconstruct the functional HCV neutralisation space. They enable high resolution profiling of HCV neutralisation and they may reflect viral functional and antigenic properties important to consider in HCV vaccine design.
Asunto(s)
Anticuerpos Neutralizantes/sangre , Hepacivirus/inmunología , Anticuerpos contra la Hepatitis C/sangre , Hepatitis C/inmunología , Secuencia de Aminoácidos , Anticuerpos Neutralizantes/inmunología , Hepacivirus/genética , Hepatitis C/virología , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunologíaRESUMEN
Hepatitis C virus (HCV) has no animal reservoir, infecting only humans. To investigate species barrier determinants limiting infection of rodents, murine liver complementary DNA library screening was performed, identifying transmembrane proteins Cd302 and Cr1l as potent restrictors of HCV propagation. Combined ectopic expression in human hepatoma cells impeded HCV uptake and cooperatively mediated transcriptional dysregulation of a noncanonical program of immunity genes. Murine hepatocyte expression of both factors was constitutive and not interferon inducible, while differences in liver expression and the ability to restrict HCV were observed between the murine orthologs and their human counterparts. Genetic ablation of endogenous Cd302 expression in human HCV entry factor transgenic mice increased hepatocyte permissiveness for an adapted HCV strain and dysregulated expression of metabolic process and host defense genes. These findings highlight human-mouse differences in liver-intrinsic antiviral immunity and facilitate the development of next-generation murine models for preclinical testing of HCV vaccine candidates.
Asunto(s)
Hepacivirus , Hepatitis C , Animales , Hepacivirus/genética , Ratones , Ratones Transgénicos , Internalización del VirusRESUMEN
BACKGROUND & AIMS: Induction of cross-reactive antibodies targeting conserved epitopes of the envelope proteins E1E2 is a key requirement for an hepatitis C virus vaccine. Conserved epitopes like the viral CD81-binding site are targeted by rare broadly neutralizing antibodies. However, these viral segments are occluded by variable regions and glycans. We aimed to identify antigens exposing conserved epitopes and to characterize their immunogenicity. METHODS: We created hepatitis C virus variants with mutated glycosylation sites and/or hypervariable region 1 (HVR1). Exposure of the CD81 binding site and conserved epitopes was quantified by soluble CD81 and antibody interaction and neutralization assays. E2 or E1-E2 heterodimers with mutations causing epitope exposure were used to immunize mice. Vaccine-induced antibodies were examined and compared with patient-derived antibodies. RESULTS: Mutant viruses bound soluble CD81 and antibodies targeting the CD81 binding site with enhanced efficacy. Mice immunized with E2 or E1E2 heterodimers incorporating these modifications mounted strong, cross-binding, and non-interfering antibodies. E2-induced antibodies neutralized the autologous virus but they were not cross-neutralizing. CONCLUSIONS: Viruses lacking the HVR1 and selected glycosylation sites expose the CD81 binding site and cross-neutralization antibody epitopes. Recombinant E2 proteins carrying these modifications induce strong cross-binding but not cross-neutralizing antibodies. LAY SUMMARY: Conserved viral epitopes can be made considerably more accessible for binding of potently neutralizing antibodies by deletion of hypervariable region 1 and selected glycosylation sites. Recombinant E2 proteins carrying these mutations are unable to elicit cross-neutralizing antibodies suggesting that exposure of conserved epitopes is not sufficient to focus antibody responses on production of cross-neutralizing antibodies.
Asunto(s)
Hepacivirus/química , Hepatitis C/inmunología , Hepatitis C/prevención & control , Proteínas del Envoltorio Viral/inmunología , Animales , Sitios de Unión/genética , Sitios de Unión/inmunología , Anticuerpos ampliamente neutralizantes/inmunología , Línea Celular Tumoral , Reacciones Cruzadas , Epítopos/inmunología , Eliminación de Gen , Glicosilación , Células HEK293 , Hepatitis C/virología , Anticuerpos contra la Hepatitis C/inmunología , Humanos , Ratones , Ratones Endogámicos BALB C , Receptores Virales/metabolismo , Tetraspanina 28/metabolismo , Vacunación , Proteínas del Envoltorio Viral/metabolismo , Proteínas Virales/genética , Proteínas Virales/metabolismo , Vacunas Virales/inmunologíaRESUMEN
The hepatitis C virus (HCV) glycoprotein E2 is the major target of neutralizing antibodies and is therefore highly relevant for vaccine design. Its structure features a central immunoglobulin (Ig)-like ß-sandwich that contributes to the binding site for the cellular receptor CD81. We show that a synthetic peptide corresponding to a ß-strand of this Ig-like domain forms an α-helix in complex with the anti-E2 antibody DAO5, demonstrating an inside-out flip of hydrophobic residues and a secondary structure change in the composite CD81 binding site. A detailed interaction analysis of DAO5 and cross-competing neutralizing antibodies with soluble E2 revealed that the Ig-like domain is trapped by different antibodies in at least two distinct conformations. DAO5 specifically captures retrovirus particles bearing HCV glycoproteins (HCVpp) and infectious cell culture-derived HCV particles (HCVcc). Infection of cells by DAO5-captured HCVpp can be blocked by a cross-competing neutralizing antibody, indicating that a single virus particle simultaneously displays E2 molecules in more than one conformation on its surface. Such conformational plasticity of the HCV E2 receptor binding site has important implications for immunogen design.IMPORTANCE Recent advances in the treatment of hepatitis C virus (HCV) infection with direct-acting antiviral drugs have enabled the control of this major human pathogen. However, due to their high costs and limited accessibility in combination with the lack of awareness of the mostly asymptomatic infection, there is an unchanged urgent need for an effective vaccine. The viral glycoprotein E2 contains regions that are crucial for virus entry into the host cell, and antibodies that bind to these regions can neutralize infection. One of the major targets of neutralizing antibodies is the central immunoglobulin (Ig)-like domain within E2. We show here that this Ig-like domain is conformationally flexible at the surface of infectious HCV particles and pseudoparticles. Our study provides novel insights into the interactions of HCV E2 with the humoral immune system that should aid future vaccine development.
Asunto(s)
Hepacivirus/química , Dominios de Inmunoglobulinas , Proteínas del Envoltorio Viral/química , Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Sitios de Unión , Cristalografía por Rayos X , Epítopos/química , Epítopos/metabolismo , Células HEK293 , Hepacivirus/inmunología , Hepacivirus/fisiología , Hepatitis C/virología , Humanos , Unión Proteica , Conformación Proteica , Tetraspanina 28/metabolismo , Proteínas del Envoltorio Viral/inmunología , Proteínas del Envoltorio Viral/metabolismo , Vacunas contra Hepatitis Viral/química , Vacunas contra Hepatitis Viral/inmunología , Internalización del VirusRESUMEN
BACKGROUND & AIMS: Hepatitis C virus (HCV) evades humoral immunity and establishes chronic infections. Virus particles circulate in complex with lipoproteins facilitating antibody escape. Apolipoprotein E (ApoE) is essential for intracellular HCV assembly and for HCV cell entry. We aimed to explore if ApoE released from non-infected cells interacts with and modulates secreted HCV particles. METHODS: ApoE secreted from non-infected cells was incubated with HCV from primary human hepatocytes or Huh-7.5 cells. Co-immunoprecipitation, viral infectivity and neutralization experiments were conducted. RESULTS: Physiological levels of secreted ApoE (10-60µg/ml) enhanced the infectivity of HCV up to 8-fold across all genotypes, which indirectly decreased virus neutralization by antibodies targeting E1 or E2 up to 10-fold. Infection enhancement was observed for particles produced in primary human hepatocytes and Huh-7.5 cells. Selective depletion of ApoE ablated infection enhancement. Addition of HA-tagged ApoE to HCV particles permitted co-precipitation of HCV virions. Serum ApoE levels ranged between 10-60µg/ml, which is ca 100-fold higher than in Huh-7.5 conditioned cell culture fluids. Serum-derived HCV particles carried much higher amounts of ApoE than cell culture-derived HCV particles. Serum ApoE levels correlated with efficiency of co-precipitation of HCV upon exogenous addition of HA-ApoE. ApoE-dependent infection enhancement was independent of the hypervariable region 1 and SR-B1, but was dependent on heparan sulfate proteoglycans (HSPGs). CONCLUSIONS: Physiological quantities of secreted ApoE stimulate HCV infection and increase antibody escape, by incorporating into virus particles and enhancing particle interactions with cellular HSPGs. Thus, secreted particles undergo ApoE-dependent maturation to enhance infectivity and to facilitate evasion from neutralizing antibodies. Lay summary: This study shows that HCV particle infectivity is remodeled by secreted ApoE after particle release from cells. Fluctuation of the availability of ApoE likely influences HCV infectivity, antibody escape and transmission.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Apolipoproteínas E/fisiología , Hepacivirus/patogenicidad , Virión/patogenicidad , Apolipoproteínas E/sangre , Línea Celular Tumoral , Heparina/análogos & derivados , Heparina/fisiología , Humanos , Proteoglicanos/fisiologíaRESUMEN
UNLABELLED: Lentiviral budding is governed by group-specific antigens (Gag proteins) and proceeds in the absence of cognate viral envelope proteins, which has been exploited to create pseudotypes incorporating envelope proteins from nonlentiviral families. Here, we report the generation of infectious lentiviral pseudoparticles incorporating human respiratory syncytial virus (hRSV) F protein alone (hRSV-Fpp) or carrying SH, G, and F proteins (hRSV-SH/G/Fpp). These particles recapitulate key infection steps of authentic hRSV particles, including utilization of glycosaminoglycans and low-pH-independent cell entry. Moreover, hRSV pseudoparticles (hRSVpp) can faithfully reproduce phenotypic resistance to a small-molecule fusion inhibitor in clinical development (BMS-433771) and a licensed therapeutic F protein-targeting antibody (palivizumab). Inoculation of several human cell lines from lung and liver revealed more than 30-fold differences in susceptibility to hRSVpp infection, suggesting differential expression of hRSV entry cofactors and/or restriction factors between these cell types. Moreover, we observed cell-type-dependent functional differences between hRSVpp carrying solely F protein or SH, G, and F proteins with regard to utilization of glycosaminoglycans. Using hRSVpp, we identified penta-O-galloyl-ß-d-glucose (PGG) as a novel hRSV cell entry inhibitor. Moreover, we show that PGG also inhibits cell entry of hRSVpp carrying F proteins resistant to BMS-433771 or palivizumab. This work sheds new light on the mechanisms of hRSV cell entry, including possible strategies for antiviral intervention. Moreover, hRSVpp should prove valuable to dissect hRSV envelope protein functions, including the interaction with cell entry factors. IMPORTANCE: Lentiviral pseudotypes are highly useful to specifically dissect the functions of viral and host factors in cell entry, which have been exploited for numerous viruses. Here, we successfully created hRSVpp and show that they faithfully recapitulate key characteristics of parental hRSV cell entry. Importantly, hRSVpp accurately mirror hRSV resistance to small-molecule fusion inhibitors and clinically approved therapeutic antibodies. Moreover, we observed highly different susceptibilities of cell lines to hRSVpp infection and also differences between hRSVpp types (with F protein alone or with SH, G, and F proteins) in regard to cell entry. This indicates differential expression of host factors determining hRSV cell entry between these cell lines and highlights the fact that the hRSVpp system is useful to explore the functional properties of hRSV envelope protein combinations. Therefore, this system will be highly useful to study hRSV cell entry and host factor usage and to explore antiviral strategies targeting hRSV cell entry.
Asunto(s)
Antivirales/farmacología , Taninos Hidrolizables/farmacología , Virus Sincitial Respiratorio Humano/efectos de los fármacos , Virus Sincitial Respiratorio Humano/fisiología , Internalización del Virus/efectos de los fármacos , Antivirales/aislamiento & purificación , Línea Celular , Vectores Genéticos , Humanos , Taninos Hidrolizables/aislamiento & purificación , Lentivirus/genética , Virus Sincitial Respiratorio Humano/genéticaRESUMEN
UNLABELLED: Hepatitis C virus (HCV) particles associate with lipoproteins and infect cells by using at least four cell entry factors. These factors include scavenger receptor class B type I (SR-BI), CD81, claudin 1 (CLDN1), and occludin (OCLN). Little is known about specific functions of individual host factors during HCV cell entry and viral domains that mediate interactions with these factors. Hypervariable region 1 (HVR1) within viral envelope protein 2 (E2) is involved in the usage of SR-BI and conceals the viral CD81 binding site. Moreover, deletion of this domain alters the density of virions. We compared lipoprotein interaction, surface attachment, receptor usage, and cell entry between wild-type HCV and a viral mutant lacking this domain. Deletion of HVR1 did not affect CD81, CLDN1, and OCLN usage. However, unlike wild-type HCV, HVR1-deleted viruses were not neutralized by antibodies and small molecules targeting SR-BI. Nevertheless, modulation of SR-BI cell surface expression altered the infection efficiencies of both viruses to similar levels. Analysis of affinity-purified virions revealed comparable levels of apolipoprotein E (ApoE) incorporation into viruses with or without HVR1. However, ApoE incorporated into these viruses was differentially recognized by ApoE-specific antibodies. Thus, SR-BI has at least two functions during cell entry. One of them can be neutralized by SR-BI-targeting molecules, and it is critical only for wild-type HCV. The other one is important for both viruses but apparently is not inactivated by the SR-BI binding antibodies and small molecules evaluated here. In addition, HVR1 modulates the conformation and/or epitope exposure of virus particle-associated ApoE. IMPORTANCE: HCV cell entry is SR-BI dependent irrespective of the presence or absence of HVR1. Moreover, this domain modulates the properties of ApoE on the surface of virus particles. These findings have implications for the development of SR-BI-targeting antivirals. Furthermore, these findings highlight separable functions of SR-BI during HCV cell entry and reveal a novel role of HVR1 for the properties of virus-associated lipoproteins.
Asunto(s)
Claudina-1/metabolismo , Hepacivirus/fisiología , Ocludina/metabolismo , Receptores Depuradores de Clase B/metabolismo , Tetraspanina 28/metabolismo , Proteínas Virales/metabolismo , Internalización del Virus , Línea Celular , Eliminación de Gen , Hepatocitos/virología , Interacciones Huésped-Patógeno , Humanos , Lipoproteínas/metabolismo , Unión Proteica , Mapeo de Interacción de Proteínas , Proteínas Virales/genéticaRESUMEN
Hepatitis C virus (HCV) infection is still a serious global health burden. Despite improved therapeutic options, a preventative vaccine would be desirable especially in undeveloped countries. Traditionally, highly conserved epitopes are targets for antibody-based prophylactic vaccines. In HCV-infected patients, however, neutralizing antibodies are primarily directed against hypervariable region I (HVRI) in the envelope protein E2. HVRI is the most variable region of HCV, and this heterogeneity contributes to viral persistence and has thus far prevented the development of an effective HVRI-based vaccine. The primary goal of an antibody-based HCV vaccine should therefore be the induction of cross-reactive HVRI antibodies. In this study we approached this problem by presenting selected cross-reactive HVRI variants in a highly symmetric repeated array on capsid-like particles (CLPs). SplitCore CLPs, a novel particulate antigen presentation system derived from the HBV core protein, were used to deliberately manipulate the orientation of HVRI and therefore enable the presentation of conserved parts of HVRI. These HVRI-CLPs induced high titers of cross-reactive antibodies, including neutralizing antibodies. The combination of only four HVRI CLPs was sufficient to induce antibodies cross-reactive with 81 of 326 (24.8%) naturally occurring HVRI peptides. Most importantly, HVRI CLPs with AS03 as an adjuvant induced antibodies with a 10-fold increase in neutralizing capability. These antibodies were able to neutralize infectious HCVcc isolates and 4 of 19 (21%) patient-derived HCVpp isolates. Taken together, these results demonstrate that the induction of at least partially cross-neutralizing antibodies is possible. This approach might be useful for the development of a prophylactic HCV vaccine and should also be adaptable to other highly variable viruses.
Asunto(s)
Anticuerpos Neutralizantes/biosíntesis , Anticuerpos Antivirales/biosíntesis , Hepacivirus/inmunología , Virus de la Hepatitis B/inmunología , Hepatitis C/prevención & control , Vacunas contra Hepatitis Viral/inmunología , Proteínas Virales/inmunología , Animales , Presentación de Antígeno , Antígenos Virales/química , Antígenos Virales/genética , Antígenos Virales/inmunología , Proteínas de la Cápside/química , Proteínas de la Cápside/genética , Proteínas de la Cápside/inmunología , Protección Cruzada , Combinación de Medicamentos , Escherichia coli/genética , Escherichia coli/metabolismo , Femenino , Expresión Génica , Virus de la Hepatitis B/genética , Hepatitis C/inmunología , Hepatitis C/virología , Humanos , Inmunidad Humoral , Inyecciones Intramusculares , Inyecciones Subcutáneas , Ratones , Ratones Endogámicos C57BL , Polisorbatos/administración & dosificación , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Escualeno/administración & dosificación , Vacunas contra Hepatitis Viral/administración & dosificación , Vacunas contra Hepatitis Viral/genética , Proteínas Virales/química , Proteínas Virales/genética , alfa-Tocoferol/administración & dosificaciónRESUMEN
UNLABELLED: Hepatitis C virus (HCV)-induced endstage liver disease is currently a major indication for liver transplantation. After transplantation the donor liver inevitably becomes infected with the circulating virus. Monoclonal antibodies (mAbs) against the HCV coreceptor scavenger receptor class B type I (SR-BI) inhibit HCV infection of different genotypes, both in cell culture and in humanized mice. Anti-SR-BI mAb therapy is successful even when initiated several days after HCV exposure, supporting its potential applicability to prevent HCV reinfection of liver allografts. However, HCV variants with reduced SR-BI dependency have been described in the literature, which could potentially limit the use of SR-BI targeting therapy. In this study we show, both in a preventative and postexposure setting, that humanized mice infected with HCV variants exhibiting increased in vitro resistance to SR-BI-targeting molecules remain responsive to anti-SR-BI mAb therapy in vivo. A 2-week antibody therapy readily cleared HCV RNA from the circulation of infected humanized mice. We found no evidence supporting increased SR-BI-receptor dependency of viral particles isolated from humanized mice compared to cell culture-produced virus. However, we observed that, unlike wild-type virus, the in vitro infectivity of the resistant variants was inhibited by both human high density lipoprotein (HDL) and very low density lipoprotein (VLDL). The combination of mAb1671 with these lipoproteins further increased the antiviral effect. CONCLUSION: HCV variants that are less dependent on SR-BI in vitro can still be efficiently blocked by an anti-SR-BI mAb in humanized mice. Since these variants are also more susceptible to neutralization by anti-HCV envelope antibodies, their chance of emerging during anti-SR-BI therapy is severely reduced. Our data indicate that anti-SR-BI receptor therapy could be an effective way to prevent HCV infection in a liver transplant setting.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Hepatitis C/tratamiento farmacológico , Receptores Depuradores de Clase B/inmunología , Animales , Línea Celular Tumoral , Hepacivirus/efectos de los fármacos , Hepacivirus/patogenicidad , Hepatitis C/virología , Humanos , Lipoproteínas/farmacología , Lipoproteínas/uso terapéutico , Ratones SCID , Resultado del Tratamiento , Ácidos TriyodobenzoicosRESUMEN
OBJECTIVE: Hepatitis C virus (HCV) infection causes severe liver disease and affects more than 160 million individuals worldwide. People undergoing liver organ transplantation face universal re-infection of the graft. Therefore, affordable antiviral strategies targeting the early stages of infection are urgently needed to prevent the recurrence of HCV infection. The aim of the study was to determine the potency of turmeric curcumin as an HCV entry inhibitor. DESIGN: The antiviral activity of curcumin and its derivatives was evaluated using HCV pseudo-particles (HCVpp) and cell-culture-derived HCV (HCVcc) in hepatoma cell lines and primary human hepatocytes. The mechanism of action was dissected using R18-labelled virions and a membrane fluidity assay. RESULTS: Curcumin treatment had no effect on HCV RNA replication or viral assembly/release. However, co-incubation of HCV with curcumin potently inhibited entry of all major HCV genotypes. Similar antiviral activities were also exerted by other curcumin derivatives but not by tetrahydrocurcumin, suggesting the importance of α,ß-unsaturated ketone groups for the antiviral activity. Expression levels of known HCV receptors were unaltered, while pretreating the virus with the compound reduced viral infectivity without viral lysis. Membrane fluidity experiments indicated that curcumin affected the fluidity of the HCV envelope resulting in impairment of viral binding and fusion. Curcumin has also been found to inhibit cell-to-cell transmission and to be effective in combination with other antiviral agents. CONCLUSIONS: Turmeric curcumin inhibits HCV entry independently of the genotype and in primary human hepatocytes by affecting membrane fluidity thereby impairing virus binding and fusion.
Asunto(s)
Antivirales/farmacología , Curcumina/farmacología , Hepacivirus/efectos de los fármacos , Hepatitis C/prevención & control , Hepatocitos/virología , Internalización del Virus/efectos de los fármacos , Animales , Antivirales/uso terapéutico , Línea Celular , Línea Celular Tumoral , Curcumina/uso terapéutico , Hepacivirus/fisiología , Hepatitis C/virología , Humanos , Ratones , Ensamble de Virus/efectos de los fármacos , Liberación del Virus/efectos de los fármacos , Replicación Viral/efectos de los fármacosRESUMEN
Hepatitis C virus (HCV) predominantly infects human hepatocytes, although extrahepatic virus reservoirs are being discussed. Infection of cells is initiated via cell-free and direct cell-to-cell transmission routes. Cell type-specific determinants of HCV entry and RNA replication have been reported. Moreover, several host factors required for synthesis and secretion of lipoproteins from liver cells, in part expressed in tissue-specific fashion, have been implicated in HCV assembly. However, the minimal cell type-specific requirements for HCV assembly have remained elusive. Here we report that production of HCV trans-complemented particles (HCVTCP) from nonliver cells depends on ectopic expression of apolipoprotein E (ApoE). For efficient virus production by full-length HCV genomes, microRNA 122 (miR-122)-mediated enhancement of RNA replication is additionally required. Typical properties of cell culture-grown HCV (HCVcc) particles from ApoE-expressing nonliver cells are comparable to those of virions derived from human hepatoma cells, although specific infectivity of virions is modestly reduced. Thus, apolipoprotein B (ApoB), microsomal triglyceride transfer protein (MTTP), and apolipoprotein C1 (ApoC1), previously implicated in HCV assembly, are dispensable for production of infectious HCV. In the absence of ApoE, release of core protein from infected cells is reduced, and production of extracellular as well as intracellular infectivity is ablated. Since envelopment of capsids was not impaired, we conclude that ApoE acts after capsid envelopment but prior to secretion of infectious HCV. Remarkably, the lack of ApoE also abrogated direct HCV cell-to-cell transmission. These findings highlight ApoE as a host factor codetermining HCV tissue tropism due to its involvement in a late assembly step and viral cell-to-cell transmission.
Asunto(s)
Apolipoproteínas E/metabolismo , Hepacivirus/fisiología , Hepatitis C/metabolismo , Hepatitis C/virología , Tropismo Viral , Ensamble de Virus , Apolipoproteínas E/genética , Línea Celular Tumoral , Hepacivirus/genética , Hepatitis C/genética , Humanos , Proteínas del Núcleo Viral/genética , Proteínas del Núcleo Viral/metabolismo , Virión/genética , Virión/fisiologíaRESUMEN
UNLABELLED: Oxidized low-density lipoprotein (oxLDL) has been reported as an inhibitor of hepatitis C virus (HCV) cell entry, making it the only known component of human lipid metabolism with an antiviral effect on HCV. However, several questions remain open, including its effect on full-length cell-culture-grown HCV (HCVcc) of different genotypes or on other steps of the viral replication cycle, its mechanism of action, and whether endogenous oxLDL shares the anti-HCV properties of in vitro-generated oxLDL. We combined molecular virology tools with oxLDL serum measurements in different patient cohorts to address these questions. We found that oxLDL inhibits HCVcc at least as potently as HCV pseudoparticles. There was moderate variation between genotypes, with genotype 4 appearing the most oxLDL sensitive. Intracellular RNA replication and assembly and release of new particles were unaffected. HCV particles entering target cells lost oxLDL sensitivity with time kinetics parallel to anti-SR-BI (scavenger receptor class B type I), but significantly earlier than anti-CD81, suggesting that oxLDL acts by perturbing interaction between HCV and SR-BI. Finally, in chronically HCV-infected individuals, endogenous serum oxLDL levels did not correlate with viral load, but in HCV-negative sera, high endogenous oxLDL had a negative effect on HCV infectivity in vitro. CONCLUSION: oxLDL is a potent pangenotype HCV entry inhibitor that maintains its activity in the context of human serum and targets an early step of HCV entry.
Asunto(s)
Hepacivirus/genética , Hepacivirus/fisiología , Hepatitis C Crónica/sangre , Lipoproteínas LDL/farmacología , Replicación Viral/efectos de los fármacos , Antígenos CD36/fisiología , Carcinoma Hepatocelular/patología , Carcinoma Hepatocelular/virología , Línea Celular Tumoral , Células Cultivadas , ADN Viral/genética , Genotipo , Hepacivirus/efectos de los fármacos , Humanos , Técnicas In Vitro , Lipoproteínas LDL/sangre , Neoplasias Hepáticas/patología , Neoplasias Hepáticas/virología , Carga Viral , Virión/fisiología , Replicación Viral/fisiologíaRESUMEN
UNLABELLED: Scavenger receptor class B type I (SR-BI) is a high-density lipoprotein (HDL) receptor highly expressed in the liver and modulating HDL metabolism. Hepatitis C virus (HCV) is able to directly interact with SR-BI and requires this receptor to efficiently enter into hepatocytes to establish productive infection. A complex interplay between lipoproteins, SR-BI and HCV envelope glycoproteins has been reported to take place during this process. SR-BI has been demonstrated to act during binding and postbinding steps of HCV entry. Although the SR-BI determinants involved in HCV binding have been partially characterized, the postbinding function of SR-BI remains largely unknown. To uncover the mechanistic role of SR-BI in viral initiation and dissemination, we generated a novel class of anti-SR-BI monoclonal antibodies that interfere with postbinding steps during the HCV entry process without interfering with HCV particle binding to the target cell surface. Using the novel class of antibodies and cell lines expressing murine and human SR-BI, we demonstrate that the postbinding function of SR-BI is of key impact for both initiation of HCV infection and viral dissemination. Interestingly, this postbinding function of SR-BI appears to be unrelated to HDL interaction but to be directly linked to its lipid transfer function. CONCLUSION: Taken together, our results uncover a crucial role of the SR-BI postbinding function for initiation and maintenance of viral HCV infection that does not require receptor-E2/HDL interactions. The dissection of the molecular mechanisms of SR-BI-mediated HCV entry opens a novel perspective for the design of entry inhibitors interfering specifically with the proviral function of SR-BI.
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Antígenos CD36/metabolismo , Hepacivirus/metabolismo , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/metabolismo , Antígenos CD36/inmunología , Línea Celular , HDL-Colesterol/antagonistas & inhibidores , HDL-Colesterol/metabolismo , Hepacivirus/inmunología , Hepacivirus/patogenicidad , Hepatitis C/prevención & control , Humanos , Lipoproteínas HDL/metabolismo , Ratones , Ratas , Receptores de Lipoproteína/metabolismoRESUMEN
Hepatitis C virus (HCV) has infected around 160 million individuals. Current therapies have limited efficacy and are fraught with side effects. To identify cellular HCV dependency factors, possible therapeutic targets, we manipulated signaling cascades with pathway-specific inhibitors. Using this approach we identified the MAPK/ERK regulated, cytosolic, calcium-dependent, group IVA phospholipase A2 (PLA2G4A) as a novel HCV dependency factor. Inhibition of PLA2G4A activity reduced core protein abundance at lipid droplets, core envelopment and secretion of particles. Moreover, released particles displayed aberrant protein composition and were 100-fold less infectious. Exogenous addition of arachidonic acid, the cleavage product of PLA2G4A-catalyzed lipolysis, but not other related poly-unsaturated fatty acids restored infectivity. Strikingly, production of infectious Dengue virus, a relative of HCV, was also dependent on PLA2G4A. These results highlight previously unrecognized parallels in the assembly pathways of these human pathogens, and define PLA2G4A-dependent lipolysis as crucial prerequisite for production of highly infectious viral progeny.
Asunto(s)
Ácido Araquidónico/farmacología , Fosfolipasas A2 Grupo IV/metabolismo , Hepacivirus/fisiología , Sistema de Señalización de MAP Quinasas , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Butadienos/farmacología , Línea Celular , Virus del Dengue/crecimiento & desarrollo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Fosfolipasas A2 Grupo IV/antagonistas & inhibidores , Fosfolipasas A2 Grupo IV/genética , Hepacivirus/crecimiento & desarrollo , Humanos , Macrófagos , Nitrilos/farmacología , Interferencia de ARN , ARN Interferente Pequeño , Vesiculovirus/crecimiento & desarrollo , Replicación Viral/efectos de los fármacos , Replicación Viral/genéticaRESUMEN
BACKGROUND: Hepatitis C virus (HCV) patients with high serum levels of bile acids (BAs) respond poorly to IFN therapy. BAs have been shown to increase RNA-replication of genotype 1 but not genotype 2a replicons. Since BAs modulate lipid metabolism including lipoprotein secretion and as HCV depends on lipids and lipoproteins during RNA-replication, virus production and cell entry, BAs may affect multiple steps of the HCV life cycle. Therefore, we analyzed the influence of BAs on individual steps of virus replication. METHODS: We measured replication of subgenomic genotype (GT) 1b and 2a RNAs as well as full-length GT2a genomes in the presence of BAs using quantitative RT-PCR and luciferase assays. Cell entry was determined using HCV pseudoparticles (HCVpp). Virus assembly and release were quantified using a core-specific ELISA. Replicon chimeras were employed to characterize genotype-specific modulation of HCV by BAs. Lunet CD81/GFP-NLS-MAVS cells were used to determine infection of Con1 particles. RESULTS: BAs increased RNA-replication of GT1b replicons up to 10-fold but had no effect on subgenomic GT2a replicons both in Huh-7 and HuH6 cells. They did not increase viral RNA translation, virus assembly and release or cell entry. Lowering replication efficiency of GT2a replicons rendered them susceptible to stimulation by BAs. Moreover, replication of full length GT1b with or without replication enhancing mutations and GT2a genomes were also stimulated by BAs. CONCLUSIONS: Bile acids specifically enhance RNA-replication. This is not limited to GT1, but also holds true for GT2a full length genomes and subgenomic replicons with low replication capacity. The increase of HCV replication by BAs may influence the efficacy of antiviral treatment in vivo and may improve replication of primary HCV genomes in cell culture.