Scavenger Receptor Class B Type I and Hepatitis C Virus Infection of Primary
            <i>Tupaia</i>
            Hepatocytes

Barth, Heidi; Cerino, Raffaele; Arcuri, Mirko; Hoffmann, M.; Schürmann, Peter; Adah, Mohammed I.; Gissler, B.; Zhao, Xingwei; Ghisetti, Valeria; Lavezzo, Bruna; Blum, Hubert E.; Weizsäcker, Fritz von; Vitelli, Alessandra; Scarselli, Elisa; Baumert, Thomas F.

doi:10.1128/jvi.79.9.5774-5785.2005

Cited by 75 publications

(58 citation statements)

References 50 publications

(86 reference statements)

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“…To analyze the specificity of the produced anti-SR-BI polyclonal serum, CHO cells were transfected with pcDNA (control vector) or pcDNA SR-BI using liposome-mediated gene transfer (Lipofectamine; Invitrogen, Karlsruhe, Germany) according to the manufacturer's protocol. CHO cells were then incubated with anti-SR-BI polyclonal serum or preimmune control serum and analyzed for cell surface SR-BI expression by flow cytometry as described previously (7). Huh-7 cells (5 ϫ 10 3 /well) were seeded into 96-well plates (Corning Inc., Corning, NY), and the following day, cells were incubated with dilutions of antibodies specific for SR-BI or CD81 (5A6 clone; a gift from Shoshana Levy, Stanford University, Stanford, CA) for 1 h at 37°C.…”

Section: Methodsmentioning

confidence: 99%

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Initiation of Hepatitis C Virus Infection Is Dependent on Cholesterol and Cooperativity between CD81 and Scavenger Receptor B Type I

Kapadia

Barth

Baumert

et al. 2007

J Virol

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In the past several years, a number of cellular proteins have been identified as candidate entry receptors for hepatitis C virus (HCV) by using surrogate models of HCV infection. Among these, the tetraspanin CD81 and scavenger receptor B type I (SR-BI), both of which localize to specialized plasma membrane domains enriched in cholesterol, have been suggested to be key players in HCV entry. In the current study, we used a recently developed in vitro HCV infection system to demonstrate that both CD81 and SR-BI are required for authentic HCV infection in vitro, that they function cooperatively to initiate HCV infection, and that CD81-mediated HCV entry is, in part, dependent on membrane cholesterol.Hepatitis C virus (HCV) is a member of the Flaviviridae family of viruses and is a major cause of chronic hepatitis and hepatocellular carcinoma (3,15). The HCV genome is a positive-strand ϳ9.6-kb RNA molecule consisting of a single open reading frame which is flanked by 5Ј and 3Ј untranslated regions (UTR). The HCV 5Ј UTR contains a highly structured internal ribosome entry site (14,50,64,78,79,86), while the 3Ј UTR is essential for replication (32,88). The HCV open reading frame encodes a single polyprotein of 3,008 to 3,037 amino acids in length that is posttranslationally processed by host and viral proteases to produce at least 10 different proteins: core protein, envelope proteins E1 and E2, p7, and nonstructural proteins NS2, NS3, NS4A, NS4B, NS5A, and NS5B (6,15,64).The host-virus interactions required during the initial steps of HCV infection are not completely understood. Prior to the development of an in vitro infectious HCV system, HCV pseudotyped retroviral particles (HCVpp), which comprise a reporter retrovirus enclosed in an envelope containing HCV glycoproteins E1 and E2, have allowed detailed analyses of the host-virus interactions required for HCVpp entry (9,10,16,30,31,34,39,46,81,83). Using a combination of HCVpp and recombinant soluble E2 glycoprotein (sE2) binding assays, a number of cellular proteins have been identified as potential candidates for HCV entry receptors, including the tetraspanin protein CD81 (61), scavenger receptor B type I (SR-BI) (68), which is a cellular protein that binds high-density lipoprotein (HDL), the low-density lipoprotein receptor (LDL-R) (1, 52), the C-type lectins L-SIGN and DC-SIGN (25,33,48,62), heparin sulfate (8), and the asialoglycoprotein receptor (67).The roles of CD81 and SR-BI as HCVpp receptors are well documented (2, 7, 9, 11, 39, 68, 91), and CD81 was recently shown to be required for cell culture-derived HCV infection (47,85,89,92). However, the extent to which SR-BI is required for HCV infection and whether it functions cooperatively with CD81 are poorly understood.Cellular cholesterol is critical for infection by many viruses (23,26,40,53,73,87). Indeed, components of the receptor complex for dengue virus, another flavivirus, are reported to be localized to cholesterol-enriched microdomains called lipid rafts, such that depletion of cholesterol by meth...

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Section: Methodsmentioning

confidence: 99%

“…The roles of CD81 and SR-BI as HCVpp receptors are well documented (2,7,9,11,39,68,91), and CD81 was recently shown to be required for cell culture-derived HCV infection (47,85,89,92). However, the extent to which SR-BI is required for HCV infection and whether it functions cooperatively with CD81 are poorly understood.…”

mentioning

confidence: 99%

Initiation of Hepatitis C Virus Infection Is Dependent on Cholesterol and Cooperativity between CD81 and Scavenger Receptor B Type I

Kapadia

Barth

Baumert

et al. 2007

J Virol

Self Cite

241

243

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“…Taken together, these results indicate that although CD81 may play a functional role as a co-factor for entry of HCV into PTHs, it is likely that other or additional molecules besides CD81 play a key role in HCV entry into PTHs. These may include other identified HCV host factors including SR-BI [27] or Claudin-1 [30] . Alternatively, other not yet identified host entry factors may mediate HCV-PTH interaction.…”

Section: Issnmentioning

confidence: 99%

“…Recently, a novel in vitro cell culture model system has been established for HCV with primary tupaia hepatocytes (PTHs) [25][26][27] . Using this cell culture system, we found that HCV E2 protein binding to PTHs and infection of PTHs with HCV could not be blocked with soluble CD81 and anti-CD81 [25] .…”

Section: Introductionmentioning

confidence: 99%

Interaction of hepatitis C virus envelope glycoprotein E2 with the large extracellular loop of tupaia CD81

Tian¹,

Shen²,

Fu³

et al. 2009

WJG

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AIM:To further analyze the interaction of tupaia CD81 with hepatitis C virus (HCV) envelope protein E2. METHODS:A tupaia CD81 large extracellular loop (CD81 LEL), which binds to HCV E2 protein, was cloned and expressed as a GST-fusion protein, and interaction of HCV E2 protein with a tupaia CD81 LEL was evaluated by enzyme-linked immunosorbent assay (EIA). RESULTS:Although tupaia and human CD81 LEL differed in 6 amino acid changes, tupaia CD81 LEL was strongly recognized by anti-CD81 antibodies against human CD81 LEL conformation-dependent epitopes. Investigating LEL CD81-E2 interactions by EIA, we demonstrated that binding of tupaia CD81 LEL GST fusion protein to recombinant HCV E2 protein was markedly reduced compared to binding of human CD81 LEL GST fusion protein to recombinant HCV E2 protein. CONCLUSION:These data suggest that the structural differences in-between the tupaia and human CD81 may alter the interaction of the large extracellular loop with HCV envelope glycoprotein E2. These findings may be important for the understanding of the mechanisms of binding and entry of HCV to PTHs.

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“…[7][8][9][10] Whereas the exact mechanism of viral entry is unknown, mounting evidence indicates that CD81 and SR-BI are key molecules. 2,[4][5][6][11][12][13][14] In an infected individual, HCV exists as a viral quasispecies. 15 HCV can be classified into at least six major genotypes that exhibit extensive genetic variability, particularly in E1 and E2.…”

mentioning

confidence: 99%

Characterization of the hepatitis C virus E2 epitope defined by the broadly neutralizing monoclonal antibody AP33

et al. 2006

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The mouse monoclonal antibody (MAb) AP33, recognizing a 12 amino acid linear epitope in the hepatitis C virus (HCV) E2 glycoprotein, potently neutralizes retroviral pseudoparticles (HCVpp) carrying genetically diverse HCV envelope glycoproteins. Consequently, this antibody and its epitope are highly relevant to vaccine design and immunotherapeutic development. The rational design of immunogens capable of inducing antibodies that target the AP33 epitope will benefit from a better understanding of this region. We have used complementary approaches, which include random peptide phage display mapping and alanine scanning mutagenesis, to identify residues in the HCV E2 protein critical for MAb AP33 binding. Four residues crucial for MAb binding were identified, which are highly conserved in HCV E2 sequences. Three residues within E2 were shown to be critical for binding to the rat MAb 3/11, which previously was shown to recognize the same 12 amino acid E2 epitope as MAb AP33 antibody, although only two of these were shared with MAb AP33. MAb AP33 bound to a panel of functional E2 proteins representative of genotypes 1-6 with higher affinity than MAb 3/11. Similarly, MAb AP33 was consistently more efficient at neutralizing infectivity by diverse HCVpp than MAb 3/11. Importantly, MAb AP33 was also able to neutralize the cell culture infectious HCV clone JFH-1. In conclusion, these data identify important protective determinants and will greatly assist the development of vaccine candidates based on the AP33 epitope. HCV, a member of the Flaviviridae family, has a 9-kb genome encoding a polyprotein precursor that is cleaved to yield three structural proteins, core, E1, and E2, together with at least six non-structural proteins. E1 and E2 are highly glycosylated membrane-anchored proteins that mediate viral entry. 2-6 E2 has been shown to bind to a number of cell surface molecules. 7-10 Whereas the exact mechanism of viral entry is unknown, mounting evidence indicates that CD81 and SR-BI are key molecules. 2,[4][5][6][11][12][13][14] In an infected individual, HCV exists as a viral quasispecies. 15 HCV can be classified into at least six major genotypes that exhibit extensive genetic variability, particularly in E1 and E2. 16 E1 and E2 are the principle targets for neutralizing antibodies, and identification of protective epitopes conserved across different strains of HCV is a major challenge for vaccine design. 17 A number of antibodies that are capable of blocking E2 binding to cells or cell receptors have been described, 18-23 some of which neutralize HCV entry in animal or in vitro models. 6,[24][25][26] The first hypervariable region of E2 contains potent neutralizing epitopes, and antibodies raised against

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Scavenger Receptor Class B Type I and Hepatitis C Virus Infection of Primary Tupaia Hepatocytes

Cited by 75 publications

References 50 publications

Initiation of Hepatitis C Virus Infection Is Dependent on Cholesterol and Cooperativity between CD81 and Scavenger Receptor B Type I

Initiation of Hepatitis C Virus Infection Is Dependent on Cholesterol and Cooperativity between CD81 and Scavenger Receptor B Type I

Interaction of hepatitis C virus envelope glycoprotein E2 with the large extracellular loop of tupaia CD81

Characterization of the hepatitis C virus E2 epitope defined by the broadly neutralizing monoclonal antibody AP33

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