The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform
Douglas G. Scraba - One of the best experts on this subject based on the ideXlab platform.
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Induction of Ferritin Synthesis in Cells Infected with Mengo Virus
The Journal of biological chemistry, 1996Co-Authors: Michael R. Mulvey, Lukas C. Kühn, Douglas G. ScrabaAbstract:We have recently identified ferritin as a cellular protein particle whose synthesis is stimulated in mouse or human cells infected by the picornaVirus Mengo. Immunoprecipitation of the particle from infected murine L929 cells showed a 4- and 6-fold increase in the intracellular concentrations of H and L apoferritin subunits, respectively. This differential expression altered the H/L subunit ratio from 3.0 in uninfected cells to 2.2 in Mengo Virus-infected cells. The induction is not due to an increase in transcription of the apoferritin L and H genes, nor is it due to an increase in stability of the apoferritin mRNAs. At the level of translation, the iron regulatory protein (IRP) remained intact, with similar amounts being detected in uninfected and infected cells. The Mengo Virus RNA genome does not compete with the iron regulatory element (IRE) for the binding of IRP, and sequence analysis confirmed that there are no IREs in the Virus RNA. The IRE binding activity of IRP in infected cells decreased approximately 30% compared with uninfected cells. The decrease in binding activity could be overcome by the addition of Desferal (deferoxamine mesylate; CIBA) an intracellular iron chelator, which suggests that Virus infection causes an increase in intracellular free iron. Electron paramagnetic resonance (EPR) studies have confirmed the increase in free iron in Mengo Virus infected cells. The permeability of cells for iron does not change in Virus infected cells, suggesting that the induction of ferritin by Mengo Virus is due to a change in the form of intracellular iron from a bound to a free state.
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Characterization of Mengo Virus Neutralization Epitopes II. Infection of Mice with an Attenuated Virus
Virology, 1995Co-Authors: Darwyn L Kobasa, Michael R. Mulvey, Joongbok Lee, Douglas G. ScrabaAbstract:Abstract A panel of five neutralizing monoclonal antibodies was generated from mice immunized with an attenuated strain of Mengo Virus. Four of the antibodies were used to select mutants of Mengo Virus which were able to escape neutralization by the selecting antibody, but it was not possible to select mutants which could escape neutralization by the fifth antibody. The capsid coding region of the RNA genome of each mutant was directly sequenced to identify the mutation(s) responsible for the neutralization escape phenotype. These results are compared to those of a previous study in which immunogenic determinants recognized by neutralizing antibodies generated against pentameric capsid subunits were located on the external surface of the Mengo virion. We have confirmed the existence of the previously identified immunogenic determinant in VP3 (site 2) as well as an immunodominant determinant in VP2 (site 1). Two previously uncharacterized determinants, located in surface loops of VP1 (sites 3 and 4), were also identified. None of the mutations conferring the neutralization escape phenotype was found near the surface depressions on the virion which are believed to be the receptor binding sites.
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Identification of Mengo Virus T helper cell epitopes.
Journal of General Virology, 1994Co-Authors: Susie Muir, James L. Bittle, Darwyn L Kobasa, Douglas G. ScrabaAbstract:To identify Mengo Virus-specific T cell epitopes in mice (the natural host for the Virus), lymph node cells were obtained from BALB/c (H-2 d ) mice, previously immunized with u.v.-inactivated Virus, and stimulated in vitro with each of 116 overlapping peptides (10 to 18 residues long) covering the entire capsid coding region (834 amino acids). T cell epitopes were defined on the basis of specific peptide-induced lymphocyte proliferation. Where proliferation occurred, immunological characterization showed that it was the CD4+ T helper (Th) cell subpopulation that was responsible for the Mengo Virus-specific response. Surprisingly, no Mengo Virus Th cell epitopes were found in capsid protein VP1 or VP4. Six peptides in VP2 (residues 1 to 15, 99 to 108, 118 to 132, 133 to 147, 227 to 236 and 247 to 256) identified the positions of separate Th cell epitopes, and two overlapping peptides (residues 173 to 182 and 178 to 192) defined an additional Th cell immunogenic sequence. Three individual peptides in VP3 (residues 46 to 58, 136 to 150 and 198 to 212) and two overlapping peptides (residues 1 to 15 and 11 to 20) also represent Th cell epitopes. Similar assays with C57BL/6 (H-2b ) and SJL/J (H-2s ) mice showed that the pattern of recognition of these peptides was H-2 restricted. Each of the previously identified sites of B cell antigenicity in VP2 and VP3 are associated with one Th epitope. Comparison of the experimentally determined Th epitopes with potential T cell epitopes identified by several predictive strategies revealed only a low correlation between authentic and predicted epitopes.
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The Cellular U-Particle, Whose Synthesis Is Induced by MengoVirus Infection, Is Homologous to Apoferritin
Virology, 1994Co-Authors: Michael R. Mulvey, Hengsheng Fang, Charles F.b. Holmes, Douglas G. ScrabaAbstract:Abstract Mengo Virus infection of mouse L-cells results in induction of the synthesis of a cellular protein-containing particle, 12 nm in diameter, which was designated U (Boege et al. (1987) Virology 159,358-367). We have purified the U-particle from Virus-infected cells by a series of chromatographic steps and found it to be composed of two polypeptide species (MW 23,000 and 25,000), present in a ratio of ∼7:3. Neither of these polypeptides is measurably glycosylated or phosphorylated and the U-particle contains no detectable nucleic acid. Several amino acid sequences obtained from CNBr fragments of the U-polypeptides identified them as the H- and L-chains of mouse apoferritin. This finding was supported by immunoblotting and electron microscopy. In terms of function, the U-particle/apoferritin effectively inhibits the translation of mRNAs in reticulocyte lysates. These experiments indicate that apoferritin may perform important functions in eukaryotic cells in addition to iron storage. Finally, we propose mechanisms to explain how Mengo Virus infection could specifically induce the synthesis of apoferritin and how increasing amounts of cytoplasmic apoferritin could facilitate Virus replication.
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Characterization of Mengo Virus neutralization epitopes.
Virology, 1991Co-Authors: Ulrike Boege, Ann C. Palmenberg, Darwyn L Kobasa, Shiroh Onodera, Griffith D. Parks, Douglas G. ScrabaAbstract:Abstract A set of four monoclonal antibodies which neutralized the infectivity of Mengo Virus was used to select 20 non-neutralizable (escape) mutants. Altered amino acids were identified by sequence analyses of the capsid-coding regions of the mutant Virus genomes. Mutations were found predominantly in proteins VP2 and VP3, while mutations in VP1 were detected only as second mutations. The Mengo Virus VP2 mutations at amino acid residues 2144, 2145, 2147, and 2148 align with site Nlm II in human rhinoVirus-14 and site 2 in polioViruses 1 and 3. The mutation at 2075 as well as those at 3057, 3061, and 3068 in VP3 correspond to site 3 in polioVirus. These alignments notwithstanding, the results of cross-neutralization experiments indicate the existence of a single composite neutralization site on the Mengo virion. Considering the three-dimensional structure of the Mengo capsid, the amino acids which are altered in the escape mutants are all exposed on the outer surface and none are found in the “pit,” the probable site for binding of a cellular receptor. The VP3 mutations are located in the VP3 “knob” and the VP2 mutations on a nearby ridge. Together these mutations define a set of epitopes within a single composite antigenic determinant which forms a crescent-shaped area around the three-fold icosahedral axes of the Mengo virion.
S Van Der Werf - One of the best experts on this subject based on the ideXlab platform.
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Lymphocytes Restricted to the Same Immunodominant
1997Co-Authors: S Van Der Werf, N Escriou, S Dethlefs, Michel BrahicAbstract:Theiler's Virus and Mengo Virus induce cross-reactive cytotoxic T lymphocytes restricted to the same immunodominant VP2 epitope in C57BL/6 mice
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Theiler's Virus and Mengo Virus induce cross-reactive cytotoxic T lymphocytes restricted to the same immunodominant VP2 epitope in C57BL/6 mice.
Journal of virology, 1997Co-Authors: S Dethlefs, S Van Der Werf, N Escriou, Michel Brahic, E L Larsson-sciardAbstract:C57BL/6 mice develop a Virus-specific cytotoxic T-lymphocyte (CTL) response after intraperitoneal inoculation with either the DA strain of Theiler's Virus or Mengo Virus, two members of the CardioVirus genus. These CTLs contribute to viral clearance in the case of Theiler's Virus but do not protect the mice from the fatal encephalomyelitis caused by Mengo Virus. In this study we show that DA and Mengo Virus-induced CTLs are cross-reactive. The cross-reactivity is due to a conserved, H-2Db-restricted epitope located between amino acid residues 122 and 130 of the VP2 capsid protein (VP2(122-130)). This epitope is immunodominant in C57BL/6 mice infected with Theiler's Virus. The VP2(122-130) epitope, initially identified for Mengo Virus, is the first CTL epitope described for Theiler's Virus.
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Attenuated Mengo Virus: a new vector for live recombinant vaccines.
Journal of virology, 1995Co-Authors: Ralf Altmeyer, Marc Girard, S Van Der Werf, V Mimic, L Seigneur, M F SaronAbstract:Several features make Mengo Virus an excellent candidate for use as a vaccine vector. The Virus has a wide host range, including rodents, pigs, monkeys, and most likely humans, and expresses its genome exclusively in the cytoplasm of the infected cell. Stable attenuated strains exist which are deleted for part of the 5' noncoding region of the genome. Here we report an attenuated Mengo Virus recombinant, vLCMG4, that encodes an immunodominant cytotoxic T-lymphocyte epitope of the lymphocytic choriomeningitis Virus (LCMV) nucleo-protein. vLCMG4 induced protective immunity against lethal LCMV infection after a single, low-dose immunization in BALB/c mice and elicited an LCMV-specific CD8+ cytotoxic T lymphocyte response. This demonstrates the potential of recombinant Mengo Virus vaccines to confer protection against infectious diseases by the induction of cellular immune responses.
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Cytotoxic T cell response to Mengo Virus in mice: effector cell phenotype and target proteins.
The Journal of general virology, 1995Co-Authors: N Escriou, C Leclerc, S Gerbard, M Giraud, S Van Der WerfAbstract:The Mengo Virus specific cytotoxic T lymphocyte (CTL) response was investigated after intraperitoneal infection of mice with the attenuated Mengo Virus strain vMC24. A high level of CTL activity was detected in spleen cell cultures obtained from infected C3H/HeJ (H-2k) or C57BL/6 (H-2b) mice after a secondary in vitro stimulation with Mengo Virus-infected cells. The CTL activity, which was MHC class I-restricted, was shown to be mediated by CD8+ T cells. Recombinant vaccinia Viruses that expressed capsid proteins VP0, VP1 or VP3 were produced and used to identify the protein(s) recognized by the Mengo Virus-specific CTLs. In both C3H/HeJ and C57BL/6 mice, analysis of CTL activity against target cells expressing each capsid protein showed that VP0 was the only capsid protein recognized by the CD8+ CTLs. The CTL epitope(s) could be further located in the C-terminal half of VP0, i.e. in capsid protein VP2. Moreover, using unlabelled target cells expressing VP0 as cold competitors, we were able to almost completely inhibit recognition and lysis of Mengo Virus-infected cells by specific CD8+ CTLs. Thus, the CTL response directed against VP2 was immunodominant in both C3H/HeJ- and C57BL/6-infected mice.
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Cytotoxic T cell response to Mengo Virus in mice: effector cell phenotype and target proteins
1995Co-Authors: N Escriou, Marc Girard, Claude L Leclerc, Sylvie Gerbaud, S Van Der WerfAbstract:response was investigated after intraperitoneal infection of mice with the attenuated Mengo Virus strain vMC24. A high level of CTL activity was detected in spleen cell cultures obtained from infected C3H/HeJ (H-2 k) or C57BL/6 (H-2 b) mice after a secondary in vitro stimu-lation with Mengo Virus-infected cells. The CTL activity, which was MHC class I-restricted, was shown to be mediated by CD8 ÷ T cells. Recombinant vaccinia Viruses that expressed capsid proteins VP0, VP1 or VP3 were produced and used to identify the protein(s) recognized by the Mengo Virus-specific CTLs. In both C3H/HeJ and C57BL/6 mice, analysis of CTL activity against target cells expressing each capsid protein showed that VP0 was the only capsid protein recognized by the CD8 + CTLs. The CTL epitope(s) could be further located in the C-terminal half of VP0, i.e. in capsid protein VP2. Moreover, using unlabelled target cells expressing VP0 as cold competitors, we were able to almost completely inhibit recognition and lysis of Mengo Virus-infected cells by specific CD8 ÷ CTLs. Thus, the CTL response directed against VP2 was immunodominant in both C3H/HeJ- and C57BL/6-infected mice
Michael R. Mulvey - One of the best experts on this subject based on the ideXlab platform.
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Induction of Ferritin Synthesis in Cells Infected with Mengo Virus
The Journal of biological chemistry, 1996Co-Authors: Michael R. Mulvey, Lukas C. Kühn, Douglas G. ScrabaAbstract:We have recently identified ferritin as a cellular protein particle whose synthesis is stimulated in mouse or human cells infected by the picornaVirus Mengo. Immunoprecipitation of the particle from infected murine L929 cells showed a 4- and 6-fold increase in the intracellular concentrations of H and L apoferritin subunits, respectively. This differential expression altered the H/L subunit ratio from 3.0 in uninfected cells to 2.2 in Mengo Virus-infected cells. The induction is not due to an increase in transcription of the apoferritin L and H genes, nor is it due to an increase in stability of the apoferritin mRNAs. At the level of translation, the iron regulatory protein (IRP) remained intact, with similar amounts being detected in uninfected and infected cells. The Mengo Virus RNA genome does not compete with the iron regulatory element (IRE) for the binding of IRP, and sequence analysis confirmed that there are no IREs in the Virus RNA. The IRE binding activity of IRP in infected cells decreased approximately 30% compared with uninfected cells. The decrease in binding activity could be overcome by the addition of Desferal (deferoxamine mesylate; CIBA) an intracellular iron chelator, which suggests that Virus infection causes an increase in intracellular free iron. Electron paramagnetic resonance (EPR) studies have confirmed the increase in free iron in Mengo Virus infected cells. The permeability of cells for iron does not change in Virus infected cells, suggesting that the induction of ferritin by Mengo Virus is due to a change in the form of intracellular iron from a bound to a free state.
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Characterization of Mengo Virus Neutralization Epitopes II. Infection of Mice with an Attenuated Virus
Virology, 1995Co-Authors: Darwyn L Kobasa, Michael R. Mulvey, Joongbok Lee, Douglas G. ScrabaAbstract:Abstract A panel of five neutralizing monoclonal antibodies was generated from mice immunized with an attenuated strain of Mengo Virus. Four of the antibodies were used to select mutants of Mengo Virus which were able to escape neutralization by the selecting antibody, but it was not possible to select mutants which could escape neutralization by the fifth antibody. The capsid coding region of the RNA genome of each mutant was directly sequenced to identify the mutation(s) responsible for the neutralization escape phenotype. These results are compared to those of a previous study in which immunogenic determinants recognized by neutralizing antibodies generated against pentameric capsid subunits were located on the external surface of the Mengo virion. We have confirmed the existence of the previously identified immunogenic determinant in VP3 (site 2) as well as an immunodominant determinant in VP2 (site 1). Two previously uncharacterized determinants, located in surface loops of VP1 (sites 3 and 4), were also identified. None of the mutations conferring the neutralization escape phenotype was found near the surface depressions on the virion which are believed to be the receptor binding sites.
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The Cellular U-Particle, Whose Synthesis Is Induced by MengoVirus Infection, Is Homologous to Apoferritin
Virology, 1994Co-Authors: Michael R. Mulvey, Hengsheng Fang, Charles F.b. Holmes, Douglas G. ScrabaAbstract:Abstract Mengo Virus infection of mouse L-cells results in induction of the synthesis of a cellular protein-containing particle, 12 nm in diameter, which was designated U (Boege et al. (1987) Virology 159,358-367). We have purified the U-particle from Virus-infected cells by a series of chromatographic steps and found it to be composed of two polypeptide species (MW 23,000 and 25,000), present in a ratio of ∼7:3. Neither of these polypeptides is measurably glycosylated or phosphorylated and the U-particle contains no detectable nucleic acid. Several amino acid sequences obtained from CNBr fragments of the U-polypeptides identified them as the H- and L-chains of mouse apoferritin. This finding was supported by immunoblotting and electron microscopy. In terms of function, the U-particle/apoferritin effectively inhibits the translation of mRNAs in reticulocyte lysates. These experiments indicate that apoferritin may perform important functions in eukaryotic cells in addition to iron storage. Finally, we propose mechanisms to explain how Mengo Virus infection could specifically induce the synthesis of apoferritin and how increasing amounts of cytoplasmic apoferritin could facilitate Virus replication.
N Escriou - One of the best experts on this subject based on the ideXlab platform.
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Theiler's Virus and Mengo Virus induce cross-reactive cytotoxic T lymphocytes restricted to the same immunodominant VP2 epitope in C57BL/6 mice.
Journal of virology, 1997Co-Authors: S Dethlefs, S Van Der Werf, N Escriou, Michel Brahic, E L Larsson-sciardAbstract:C57BL/6 mice develop a Virus-specific cytotoxic T-lymphocyte (CTL) response after intraperitoneal inoculation with either the DA strain of Theiler's Virus or Mengo Virus, two members of the CardioVirus genus. These CTLs contribute to viral clearance in the case of Theiler's Virus but do not protect the mice from the fatal encephalomyelitis caused by Mengo Virus. In this study we show that DA and Mengo Virus-induced CTLs are cross-reactive. The cross-reactivity is due to a conserved, H-2Db-restricted epitope located between amino acid residues 122 and 130 of the VP2 capsid protein (VP2(122-130)). This epitope is immunodominant in C57BL/6 mice infected with Theiler's Virus. The VP2(122-130) epitope, initially identified for Mengo Virus, is the first CTL epitope described for Theiler's Virus.
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Lymphocytes Restricted to the Same Immunodominant
1997Co-Authors: S Van Der Werf, N Escriou, S Dethlefs, Michel BrahicAbstract:Theiler's Virus and Mengo Virus induce cross-reactive cytotoxic T lymphocytes restricted to the same immunodominant VP2 epitope in C57BL/6 mice
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Cytotoxic T cell response to Mengo Virus in mice: effector cell phenotype and target proteins.
The Journal of general virology, 1995Co-Authors: N Escriou, C Leclerc, S Gerbard, M Giraud, S Van Der WerfAbstract:The Mengo Virus specific cytotoxic T lymphocyte (CTL) response was investigated after intraperitoneal infection of mice with the attenuated Mengo Virus strain vMC24. A high level of CTL activity was detected in spleen cell cultures obtained from infected C3H/HeJ (H-2k) or C57BL/6 (H-2b) mice after a secondary in vitro stimulation with Mengo Virus-infected cells. The CTL activity, which was MHC class I-restricted, was shown to be mediated by CD8+ T cells. Recombinant vaccinia Viruses that expressed capsid proteins VP0, VP1 or VP3 were produced and used to identify the protein(s) recognized by the Mengo Virus-specific CTLs. In both C3H/HeJ and C57BL/6 mice, analysis of CTL activity against target cells expressing each capsid protein showed that VP0 was the only capsid protein recognized by the CD8+ CTLs. The CTL epitope(s) could be further located in the C-terminal half of VP0, i.e. in capsid protein VP2. Moreover, using unlabelled target cells expressing VP0 as cold competitors, we were able to almost completely inhibit recognition and lysis of Mengo Virus-infected cells by specific CD8+ CTLs. Thus, the CTL response directed against VP2 was immunodominant in both C3H/HeJ- and C57BL/6-infected mice.
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Cytotoxic T cell response to Mengo Virus in mice: effector cell phenotype and target proteins
1995Co-Authors: N Escriou, Marc Girard, Claude L Leclerc, Sylvie Gerbaud, S Van Der WerfAbstract:response was investigated after intraperitoneal infection of mice with the attenuated Mengo Virus strain vMC24. A high level of CTL activity was detected in spleen cell cultures obtained from infected C3H/HeJ (H-2 k) or C57BL/6 (H-2 b) mice after a secondary in vitro stimu-lation with Mengo Virus-infected cells. The CTL activity, which was MHC class I-restricted, was shown to be mediated by CD8 ÷ T cells. Recombinant vaccinia Viruses that expressed capsid proteins VP0, VP1 or VP3 were produced and used to identify the protein(s) recognized by the Mengo Virus-specific CTLs. In both C3H/HeJ and C57BL/6 mice, analysis of CTL activity against target cells expressing each capsid protein showed that VP0 was the only capsid protein recognized by the CD8 + CTLs. The CTL epitope(s) could be further located in the C-terminal half of VP0, i.e. in capsid protein VP2. Moreover, using unlabelled target cells expressing VP0 as cold competitors, we were able to almost completely inhibit recognition and lysis of Mengo Virus-infected cells by specific CD8 ÷ CTLs. Thus, the CTL response directed against VP2 was immunodominant in both C3H/HeJ- and C57BL/6-infected mice
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Attenuated Mengo Virus as a vector for immunogenic human immunodeficiency Virus type 1 glycoprotein 120.
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Ralf Altmeyer, Ann C. Palmenberg, Marc Girard, N Escriou, S Van Der WerfAbstract:Introduction of a sequence encoding 147 amino acids from human immunodeficiency Virus type I (HIV-1) strain MN glycoprotein gp120 into the RNA genome of the stably attenuated Mengo Virus strain vM16 yielded an infectious recombinant Virus, vMLN450, which expressed the heterologous HIV-1 sequence along with the normal Mengo Virus proteins. The HIV-1 gp120 sequence, fused to the amino terminus of the short, nonstructural Mengo Virus leader polypeptide was recognized by a gp120 V3 loop-specific monoclonal antibody. When inoculated into mice, recombinant Virus vMLN450 elicited a high-titer anti-HIV-1 antibody response as well as an HIV-1MN-specific cytotoxic cellular immune response. An anti-HIV-1 antibody response could also be detected in cynomolgus monkeys after a single immunization. We propose that attenuated Mengo Virus can serve as an effective expression vector in cell systems and various animal species and offers another approach to the development of new, live recombinant vaccines.
Darwyn L Kobasa - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Mengo Virus Neutralization Epitopes II. Infection of Mice with an Attenuated Virus
Virology, 1995Co-Authors: Darwyn L Kobasa, Michael R. Mulvey, Joongbok Lee, Douglas G. ScrabaAbstract:Abstract A panel of five neutralizing monoclonal antibodies was generated from mice immunized with an attenuated strain of Mengo Virus. Four of the antibodies were used to select mutants of Mengo Virus which were able to escape neutralization by the selecting antibody, but it was not possible to select mutants which could escape neutralization by the fifth antibody. The capsid coding region of the RNA genome of each mutant was directly sequenced to identify the mutation(s) responsible for the neutralization escape phenotype. These results are compared to those of a previous study in which immunogenic determinants recognized by neutralizing antibodies generated against pentameric capsid subunits were located on the external surface of the Mengo virion. We have confirmed the existence of the previously identified immunogenic determinant in VP3 (site 2) as well as an immunodominant determinant in VP2 (site 1). Two previously uncharacterized determinants, located in surface loops of VP1 (sites 3 and 4), were also identified. None of the mutations conferring the neutralization escape phenotype was found near the surface depressions on the virion which are believed to be the receptor binding sites.
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Identification of Mengo Virus T helper cell epitopes.
Journal of General Virology, 1994Co-Authors: Susie Muir, James L. Bittle, Darwyn L Kobasa, Douglas G. ScrabaAbstract:To identify Mengo Virus-specific T cell epitopes in mice (the natural host for the Virus), lymph node cells were obtained from BALB/c (H-2 d ) mice, previously immunized with u.v.-inactivated Virus, and stimulated in vitro with each of 116 overlapping peptides (10 to 18 residues long) covering the entire capsid coding region (834 amino acids). T cell epitopes were defined on the basis of specific peptide-induced lymphocyte proliferation. Where proliferation occurred, immunological characterization showed that it was the CD4+ T helper (Th) cell subpopulation that was responsible for the Mengo Virus-specific response. Surprisingly, no Mengo Virus Th cell epitopes were found in capsid protein VP1 or VP4. Six peptides in VP2 (residues 1 to 15, 99 to 108, 118 to 132, 133 to 147, 227 to 236 and 247 to 256) identified the positions of separate Th cell epitopes, and two overlapping peptides (residues 173 to 182 and 178 to 192) defined an additional Th cell immunogenic sequence. Three individual peptides in VP3 (residues 46 to 58, 136 to 150 and 198 to 212) and two overlapping peptides (residues 1 to 15 and 11 to 20) also represent Th cell epitopes. Similar assays with C57BL/6 (H-2b ) and SJL/J (H-2s ) mice showed that the pattern of recognition of these peptides was H-2 restricted. Each of the previously identified sites of B cell antigenicity in VP2 and VP3 are associated with one Th epitope. Comparison of the experimentally determined Th epitopes with potential T cell epitopes identified by several predictive strategies revealed only a low correlation between authentic and predicted epitopes.
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Identification of Mengo Virus T helper cell epitopes
1994Co-Authors: Susie Muir, James L. Bittle, Darwyn L Kobasa, Douglas ScrabaAbstract:To identify Mengo Virus-specific T cell epitopes in mice (the natural host for the Virus), lymph node cells were obtained from BALB/c (H-2 a) mice, previously immunized with u.v.-inactivated Virus, and stimulated in vitro with each of 116 overlapping peptides (10 to 18 residues long) covering the entire capsid coding region (834 amino acids). T cell epitopes were defined on the basis of specific peptide-induced lymphocyte prolifera-tion. Where proliferation occurred, immunological characterization showed that it was the CD4 ÷ T helper (Th) cell subpopulation that was responsible for the Mengo Virus-specific response. Surprisingly, no Mengo Virus T h cell epitopes were found in capsid protein VP1 or VP4. Six peptides in VP2 (residues 1to 15, 99 to 108
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Characterization of Mengo Virus neutralization epitopes.
Virology, 1991Co-Authors: Ulrike Boege, Ann C. Palmenberg, Darwyn L Kobasa, Shiroh Onodera, Griffith D. Parks, Douglas G. ScrabaAbstract:Abstract A set of four monoclonal antibodies which neutralized the infectivity of Mengo Virus was used to select 20 non-neutralizable (escape) mutants. Altered amino acids were identified by sequence analyses of the capsid-coding regions of the mutant Virus genomes. Mutations were found predominantly in proteins VP2 and VP3, while mutations in VP1 were detected only as second mutations. The Mengo Virus VP2 mutations at amino acid residues 2144, 2145, 2147, and 2148 align with site Nlm II in human rhinoVirus-14 and site 2 in polioViruses 1 and 3. The mutation at 2075 as well as those at 3057, 3061, and 3068 in VP3 correspond to site 3 in polioVirus. These alignments notwithstanding, the results of cross-neutralization experiments indicate the existence of a single composite neutralization site on the Mengo virion. Considering the three-dimensional structure of the Mengo capsid, the amino acids which are altered in the escape mutants are all exposed on the outer surface and none are found in the “pit,” the probable site for binding of a cellular receptor. The VP3 mutations are located in the VP3 “knob” and the VP2 mutations on a nearby ridge. Together these mutations define a set of epitopes within a single composite antigenic determinant which forms a crescent-shaped area around the three-fold icosahedral axes of the Mengo virion.