Kathy Vielhuber - Academia.edu (original) (raw)

Papers by Kathy Vielhuber

Research paper thumbnail of Multispecific Vaccine-Induced Mucosal Cytotoxic T Lymphocytes Reduce Acute-Phase Viral Replication but Fail in Long-Term Control of Simian Immunodeficiency Virus SIVmac239

Journal of Virology, 2003

To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-speci... more To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-specific antibody, on the control of an immunodeficiency virus challenge, we vaccinated Mamu-A*01 ؉ macaques with constructs encoding a combination of CTL epitopes and full-length proteins (Tat, Rev, and Nef) by using a DNA prime/recombinant modified vaccinia virus Ankara (rMVA) boost regimen. The vaccination induced virusspecific CTL and CD4 ؉ helper T lymphocytes with CTL frequencies as high as 20,000/million peripheral blood mononuclear cells. The final rMVA vaccination, delivered intravenously, engendered long-lived mucosal CTL. At 16 weeks after the final rMVA vaccination, the vaccinees and naive, Mamu-A*01 ؉ controls were challenged intrarectally with SIVmac239. Massive early anamnestic cellular immune responses controlled acute-phase viral replication; however, the three vaccinees were unable to control virus replication in the chronic phase. The present study suggests that multispecific mucosal CTL, in the absence of neutralizing antibodies, can achieve a modicum of control over early viral replication but are unable to control chronic-phase viral replication after a high-dose mucosal challenge with a pathogenic simian immunodeficiency virus.

Research paper thumbnail of 124 A THREE-DIMENSIONAL IN VITRO IMPLANTATION MODEL WITH NONHUMAN PRIMATE EMBRYOS AND EXTRACELLULAR MATRIX UNDER VARIOUS CULTURE CONDITIONS

Reproduction, Fertility and Development, 2008

ABSTRACT The need for blastocyst culture and post-implantation embryo research has emerged in the... more ABSTRACT The need for blastocyst culture and post-implantation embryo research has emerged in the past few years. Our objective is to evaluate a novel in vitro model to study implantation and placenta formation in vitro with rhesus macaque embryos under various culture conditions. A novel nonhuman primate in vitro 3-D system can provide cues for implantation and interaction with the extracellular environment not available in 2-D planar models. Optimization of such a model can be tested with diverse culture environments. We developed and evaluated an in vitro 3-D implantation model utilizing IVF-derived, blastocyst-stage rhesus macaque embryos embedded in 3-D Matrigel droplets cultured with different feeder cells and media. Signs of implantation including enlargement of the embryo mass, invasion and proliferation of trophectoderm cell layers, cystic formation, and cellular outgrowths derived from the embryo were initiated within the first week post-embedding. Trophoblast structures with protrusion and branches growing from the surface of embryo implants were observed. Immunohistochemical staining for chorionic gonadotropin (CG) combined with immunoassays for CG and progesterone indicated differentiation of trophoblastic cell lineages. In addition, we found morphological factors, such as proliferation of embryonic and extraembryonic structures, as well as initiation of protrusions interacting with the extracellular matrix, to predict successful establishment of prolonged embryo development. We further evaluated effects of different types of feeder cells and media combinations, and found that a combination of BRL, Ishikawa cells, and human uterine fibroblasts, provided an optimized culture microenvironment to promote peri-implantation embryo development and hormone secretion including CG and progesterone. In conclusion, we have established a 3-D in vitro system modeling implantation initiation, and demonstrating the capability of the embryo to interact with the extracellular matrix. Further studies will facilitate the methodology of peri-implantation blastocyst culture and accelerate our understanding of nonhuman primate embryo development, with potential for insights into early pregnancy loss and related pathologies. The present study and future directions may be extended to provide retrospective views on blastocyst selection for embryo transfer in assisted reproductive technology. This study was funded by NIH grants RR000167, RR21876, and HD053926.

Research paper thumbnail of Visual field defects in cats with neonatal or adult immunological loss of retinal ganglion cells

Brain Research, 1986

Key words: vision --Y cell --~z cell --head orientation --retina --superior colliculus --lateral ... more Key words: vision --Y cell --~z cell --head orientation --retina --superior colliculus --lateral geniculate nucleus --antibody Behavioral perimetry methods werc used to assess the monocular visual fields of 12 cats that had received intraocutar injections of antibodies against large (a/Y) retinal ganglion cells. The antibodies produced defects in head and eye orientation responses to stimuli presented in the nasal visual field of the treated eye; responses to stimuli in the temporal visual hemifield were normal. Similar results were seen in cats that received antibody injections at 4 weeks of age or as adults. In the context of previous results, these findings suggest that a loss of Y cells in the lateral geniculate nucleus is sufficient to reduce geniculocortical function for head and eye orientation to visual stimuli in the nasal visual field.

Research paper thumbnail of Differences Between T Cell Epitopes Recognized After Immunization and After Infection1

Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SI... more Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SIV replication in infected individuals. Several vaccine strategies have therefore targeted these CD8 ؉ and CD4 ؉ responses. Whether vaccination induces the same repertoire of responses seen after infection is, however, a key unanswered question in HIV vaccine development. We therefore compared the epitope specificity induced by vaccination to that present postchallenge in the peripheral blood. Intracellular cytokine staining of PBMC stimulated with overlapping 15/20-mer peptides spanning the proteins of SIV were measured after DNA/modified vaccinia Ankara vaccination of eight rhesus macaques. Lymphocytes from 8 animals recognized a total of 39 CD8 epitopes and 41 CD4 epitopes encoded by the vaccine. T cell responses were again monitored after challenge with SIVmac239 to investigate the evolution of these responses. Only 57% of all CD8 ؉ T cell responses and 19% of all CD4 ؉ T cell responses present after vaccination were recalled after infection as measured in the peripheral blood. Interestingly, 29 new CD8 epitopes and 5 new CD4 epitopes were recognized by PBMC in the acute phase. These new epitopes were not detected after vaccination, and only some of them were maintained in the chronic phase (33% of CD8 and no CD4 responses). Additionally, 24 new CD8 epitopes and 7 new CD4 epitopes were recognized by PBMC in the chronic phase of infection. The repertoire of the immune response detected in the peripheral blood after immunization substantially differed from the immune response detected in the peripheral blood after infection.

Research paper thumbnail of Differences Between T Cell Epitopes Recognized After Immunization and After Infection

The Journal of Immunology, 2002

Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SI... more Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SIV replication in infected individuals. Several vaccine strategies have therefore targeted these CD8 ؉ and CD4 ؉ responses. Whether vaccination induces the same repertoire of responses seen after infection is, however, a key unanswered question in HIV vaccine development. We therefore compared the epitope specificity induced by vaccination to that present postchallenge in the peripheral blood. Intracellular cytokine staining of PBMC stimulated with overlapping 15/20-mer peptides spanning the proteins of SIV were measured after DNA/modified vaccinia Ankara vaccination of eight rhesus macaques. Lymphocytes from 8 animals recognized a total of 39 CD8 epitopes and 41 CD4 epitopes encoded by the vaccine. T cell responses were again monitored after challenge with SIVmac239 to investigate the evolution of these responses. Only 57% of all CD8 ؉ T cell responses and 19% of all CD4 ؉ T cell responses present after vaccination were recalled after infection as measured in the peripheral blood. Interestingly, 29 new CD8 epitopes and 5 new CD4 epitopes were recognized by PBMC in the acute phase. These new epitopes were not detected after vaccination, and only some of them were maintained in the chronic phase (33% of CD8 and no CD4 responses). Additionally, 24 new CD8 epitopes and 7 new CD4 epitopes were recognized by PBMC in the chronic phase of infection. The repertoire of the immune response detected in the peripheral blood after immunization substantially differed from the immune response detected in the peripheral blood after infection.

Research paper thumbnail of Immunization of Rhesus Macaques with a DNA Prime/Modified Vaccinia Virus Ankara Boost Regimen Induces Broad Simian Immunodeficiency Virus (SIV)Specific T-Cell Responses and Reduces Initial Viral Replication but Does Not Prevent Disease Progression following Challenge with Pathogenic SIVmac239

Journal of Virology, 2002

Most biological isolates of HIV are difficult to neutralize, so that conventional subunit-based a... more Most biological isolates of HIV are difficult to neutralize, so that conventional subunit-based antibody-inducing vaccines are unlikely to be very effective. In the rhesus macaque model, some protection was afforded by DNA/recombinant viral vector vaccines. However, these studies used as the challenge virus SHIV-89.6P, which is neutralizable, making it difficult to determine whether the observed protection was due to cellular immunity, humoral immunity, or a combination of both. In this study, we used a DNA prime/modified vaccinia virus Ankara boost regimen to immunize rhesus macaques against nearly all simian immunodeficiency virus (SIV) proteins. These animals were challenged intrarectally with pathogenic molecularly cloned SIVmac239, which is resistant to neutralization. The immunization regimen resulted in the induction of virus-specific CD8 ؉ and CD4 ؉ responses in all vaccinees. Although anamnestic neutralizing antibody responses against laboratoryadapted SIVmac251 developed after the challenge, no neutralizing antibodies against SIVmac239 were detectable. Vaccinated animals had significantly reduced peak viremia compared with controls (P < 0.01). However, despite the induction of virus-specific cellular immune responses and reduced peak viral loads, most animals still suffered from gradual CD4 depletion and progressed to disease.

Research paper thumbnail of Multispecific Vaccine-Induced Mucosal Cytotoxic T Lymphocytes Reduce Acute-Phase Viral Replication but Fail in Long-Term Control of Simian Immunodeficiency Virus SIVmac239

Journal of Virology, 2003

To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-speci... more To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-specific antibody, on the control of an immunodeficiency virus challenge, we vaccinated Mamu-A*01 ؉ macaques with constructs encoding a combination of CTL epitopes and full-length proteins (Tat, Rev, and Nef) by using a DNA prime/recombinant modified vaccinia virus Ankara (rMVA) boost regimen. The vaccination induced virusspecific CTL and CD4 ؉ helper T lymphocytes with CTL frequencies as high as 20,000/million peripheral blood mononuclear cells. The final rMVA vaccination, delivered intravenously, engendered long-lived mucosal CTL. At 16 weeks after the final rMVA vaccination, the vaccinees and naive, Mamu-A*01 ؉ controls were challenged intrarectally with SIVmac239. Massive early anamnestic cellular immune responses controlled acute-phase viral replication; however, the three vaccinees were unable to control virus replication in the chronic phase. The present study suggests that multispecific mucosal CTL, in the absence of neutralizing antibodies, can achieve a modicum of control over early viral replication but are unable to control chronic-phase viral replication after a high-dose mucosal challenge with a pathogenic simian immunodeficiency virus.

Research paper thumbnail of PATHOGENESIS AND IMMUNITY-Dominance of CD8 Responses Specific for Epitopes Bound by a Single Major Histocompatibility Complex Class I Molecule during the Acute Phase of Viral Infection

Journal of Virology, 2002

Research paper thumbnail of Escape in one of two cytotoxic T-lymphocyte epitopes bound by a high-frequency major histocompatibility complex class I molecule, Mamu-A* 02: a paradigm for virus evolution and persistence?

Journal of Virology, Nov 15, 2002

Mamu-A*01. Here we describe two novel epitopes derived from SIV, one from Gag (Gag 71-79 GY9), an... more Mamu-A*01. Here we describe two novel epitopes derived from SIV, one from Gag (Gag 71-79 GY9), and one from the Nef protein (Nef 159-167 YY9). Both epitopes are bound by the common macaque MHC class I molecule, Mamu-A*02. The sequences of these two eptiopes are consistent with the molecule's peptide-binding motif, which we have defined by elution of natural ligands from Mamu-A*02. Strikingly, we found evidence for the selection of escape variant viruses by CTL specific for Nef 159-167 YY9 in 6 of 6 Mamu-A*02-positive animals. In contrast, viral sequences encoding the Gag 71-79 GY9 epitope remained intact in each animal. This situation is reminiscent of Mamu-A*01-restricted CTL that recognize Tat 28-35 SL8, which reproducibly selects for escape variants during acute infection, and Gag 181-189 CM9, which does not. Differential selection by CTL may therefore be a paradigm of immunodeficiency virus infection.

Research paper thumbnail of Dominance of CD8 responses specific for epitopes bound by a single major histocompatibility complex class I molecule during the acute phase of viral infection

Journal of virology, Jan 15, 2002

Cytotoxic T-lymphocyte (CTL) responses are thought to control human immunodeficiency virus replic... more Cytotoxic T-lymphocyte (CTL) responses are thought to control human immunodeficiency virus replication during the acute phase of infection. Understanding the CD8+ T-cell immune responses early after infection may, therefore, be important to vaccine design. Analyzing these responses in humans is difficult since few patients are diagnosed during early infection. Additionally, patients are infected by a variety of viral subtypes, making it hard to design reagents to measure their acute-phase immune responses. Given the complexities in evaluating acute-phase CD8+ responses in humans, we analyzed these important immune responses in rhesus macaques expressing a common rhesus macaque major histocompatibility complex class I molecule (Mamu-A*01) for which we had developed a variety of immunological assays. We infected eight Mamu-A*01-positive macaques and five Mamu-A*01-negative macaques with the molecularly cloned virus SIVmac239 and determined all of the simian immunodeficiency virus-specific CD8+ T-cell responses against overlapping peptides spanning the entire virus. We also monitored the evolution of particular CD8+ T-cell responses by tetramer staining of peripheral lymphocytes as well as lymph node cells in situ. In this first analysis of the entire CD8+ immune response to autologous virus we show that between 2 and 12 responses are detected during the acute phase in each animal. CTL against the early proteins (Tat, Rev, and Nef) and against regulatory proteins Vif and Vpr dominated the acute phase. Interestingly, CD8+ responses against Mamu-A*01-restricted epitopes Tat28-35SL8 and Gag181-189CM9 were immunodominant in the acute phase. After the acute phase, however, this pattern of reactivity changed, and the Mamu-A*01-restricted response against the Gag181-189CM9 epitope became dominant. In most of the Mamu-A*01-positive macaques tested, CTL responses against epitopes bound by Mamu-A*01 dominated the CD8+ cellular immune response.

Research paper thumbnail of Multispecific Vaccine-Induced Mucosal Cytotoxic T Lymphocytes Reduce Acute-Phase Viral Replication but Fail in Long-Term Control of Simian Immunodeficiency Virus SIVmac239

Journal of Virology, 2003

To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-speci... more To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-specific antibody, on the control of an immunodeficiency virus challenge, we vaccinated Mamu-A*01 ؉ macaques with constructs encoding a combination of CTL epitopes and full-length proteins (Tat, Rev, and Nef) by using a DNA prime/recombinant modified vaccinia virus Ankara (rMVA) boost regimen. The vaccination induced virusspecific CTL and CD4 ؉ helper T lymphocytes with CTL frequencies as high as 20,000/million peripheral blood mononuclear cells. The final rMVA vaccination, delivered intravenously, engendered long-lived mucosal CTL. At 16 weeks after the final rMVA vaccination, the vaccinees and naive, Mamu-A*01 ؉ controls were challenged intrarectally with SIVmac239. Massive early anamnestic cellular immune responses controlled acute-phase viral replication; however, the three vaccinees were unable to control virus replication in the chronic phase. The present study suggests that multispecific mucosal CTL, in the absence of neutralizing antibodies, can achieve a modicum of control over early viral replication but are unable to control chronic-phase viral replication after a high-dose mucosal challenge with a pathogenic simian immunodeficiency virus.

Research paper thumbnail of 124 A THREE-DIMENSIONAL IN VITRO IMPLANTATION MODEL WITH NONHUMAN PRIMATE EMBRYOS AND EXTRACELLULAR MATRIX UNDER VARIOUS CULTURE CONDITIONS

Reproduction, Fertility and Development, 2008

ABSTRACT The need for blastocyst culture and post-implantation embryo research has emerged in the... more ABSTRACT The need for blastocyst culture and post-implantation embryo research has emerged in the past few years. Our objective is to evaluate a novel in vitro model to study implantation and placenta formation in vitro with rhesus macaque embryos under various culture conditions. A novel nonhuman primate in vitro 3-D system can provide cues for implantation and interaction with the extracellular environment not available in 2-D planar models. Optimization of such a model can be tested with diverse culture environments. We developed and evaluated an in vitro 3-D implantation model utilizing IVF-derived, blastocyst-stage rhesus macaque embryos embedded in 3-D Matrigel droplets cultured with different feeder cells and media. Signs of implantation including enlargement of the embryo mass, invasion and proliferation of trophectoderm cell layers, cystic formation, and cellular outgrowths derived from the embryo were initiated within the first week post-embedding. Trophoblast structures with protrusion and branches growing from the surface of embryo implants were observed. Immunohistochemical staining for chorionic gonadotropin (CG) combined with immunoassays for CG and progesterone indicated differentiation of trophoblastic cell lineages. In addition, we found morphological factors, such as proliferation of embryonic and extraembryonic structures, as well as initiation of protrusions interacting with the extracellular matrix, to predict successful establishment of prolonged embryo development. We further evaluated effects of different types of feeder cells and media combinations, and found that a combination of BRL, Ishikawa cells, and human uterine fibroblasts, provided an optimized culture microenvironment to promote peri-implantation embryo development and hormone secretion including CG and progesterone. In conclusion, we have established a 3-D in vitro system modeling implantation initiation, and demonstrating the capability of the embryo to interact with the extracellular matrix. Further studies will facilitate the methodology of peri-implantation blastocyst culture and accelerate our understanding of nonhuman primate embryo development, with potential for insights into early pregnancy loss and related pathologies. The present study and future directions may be extended to provide retrospective views on blastocyst selection for embryo transfer in assisted reproductive technology. This study was funded by NIH grants RR000167, RR21876, and HD053926.

Research paper thumbnail of Visual field defects in cats with neonatal or adult immunological loss of retinal ganglion cells

Brain Research, 1986

Key words: vision --Y cell --~z cell --head orientation --retina --superior colliculus --lateral ... more Key words: vision --Y cell --~z cell --head orientation --retina --superior colliculus --lateral geniculate nucleus --antibody Behavioral perimetry methods werc used to assess the monocular visual fields of 12 cats that had received intraocutar injections of antibodies against large (a/Y) retinal ganglion cells. The antibodies produced defects in head and eye orientation responses to stimuli presented in the nasal visual field of the treated eye; responses to stimuli in the temporal visual hemifield were normal. Similar results were seen in cats that received antibody injections at 4 weeks of age or as adults. In the context of previous results, these findings suggest that a loss of Y cells in the lateral geniculate nucleus is sufficient to reduce geniculocortical function for head and eye orientation to visual stimuli in the nasal visual field.

Research paper thumbnail of Differences Between T Cell Epitopes Recognized After Immunization and After Infection1

Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SI... more Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SIV replication in infected individuals. Several vaccine strategies have therefore targeted these CD8 ؉ and CD4 ؉ responses. Whether vaccination induces the same repertoire of responses seen after infection is, however, a key unanswered question in HIV vaccine development. We therefore compared the epitope specificity induced by vaccination to that present postchallenge in the peripheral blood. Intracellular cytokine staining of PBMC stimulated with overlapping 15/20-mer peptides spanning the proteins of SIV were measured after DNA/modified vaccinia Ankara vaccination of eight rhesus macaques. Lymphocytes from 8 animals recognized a total of 39 CD8 epitopes and 41 CD4 epitopes encoded by the vaccine. T cell responses were again monitored after challenge with SIVmac239 to investigate the evolution of these responses. Only 57% of all CD8 ؉ T cell responses and 19% of all CD4 ؉ T cell responses present after vaccination were recalled after infection as measured in the peripheral blood. Interestingly, 29 new CD8 epitopes and 5 new CD4 epitopes were recognized by PBMC in the acute phase. These new epitopes were not detected after vaccination, and only some of them were maintained in the chronic phase (33% of CD8 and no CD4 responses). Additionally, 24 new CD8 epitopes and 7 new CD4 epitopes were recognized by PBMC in the chronic phase of infection. The repertoire of the immune response detected in the peripheral blood after immunization substantially differed from the immune response detected in the peripheral blood after infection.

Research paper thumbnail of Differences Between T Cell Epitopes Recognized After Immunization and After Infection

The Journal of Immunology, 2002

Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SI... more Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SIV replication in infected individuals. Several vaccine strategies have therefore targeted these CD8 ؉ and CD4 ؉ responses. Whether vaccination induces the same repertoire of responses seen after infection is, however, a key unanswered question in HIV vaccine development. We therefore compared the epitope specificity induced by vaccination to that present postchallenge in the peripheral blood. Intracellular cytokine staining of PBMC stimulated with overlapping 15/20-mer peptides spanning the proteins of SIV were measured after DNA/modified vaccinia Ankara vaccination of eight rhesus macaques. Lymphocytes from 8 animals recognized a total of 39 CD8 epitopes and 41 CD4 epitopes encoded by the vaccine. T cell responses were again monitored after challenge with SIVmac239 to investigate the evolution of these responses. Only 57% of all CD8 ؉ T cell responses and 19% of all CD4 ؉ T cell responses present after vaccination were recalled after infection as measured in the peripheral blood. Interestingly, 29 new CD8 epitopes and 5 new CD4 epitopes were recognized by PBMC in the acute phase. These new epitopes were not detected after vaccination, and only some of them were maintained in the chronic phase (33% of CD8 and no CD4 responses). Additionally, 24 new CD8 epitopes and 7 new CD4 epitopes were recognized by PBMC in the chronic phase of infection. The repertoire of the immune response detected in the peripheral blood after immunization substantially differed from the immune response detected in the peripheral blood after infection.

Research paper thumbnail of Immunization of Rhesus Macaques with a DNA Prime/Modified Vaccinia Virus Ankara Boost Regimen Induces Broad Simian Immunodeficiency Virus (SIV)Specific T-Cell Responses and Reduces Initial Viral Replication but Does Not Prevent Disease Progression following Challenge with Pathogenic SIVmac239

Journal of Virology, 2002

Most biological isolates of HIV are difficult to neutralize, so that conventional subunit-based a... more Most biological isolates of HIV are difficult to neutralize, so that conventional subunit-based antibody-inducing vaccines are unlikely to be very effective. In the rhesus macaque model, some protection was afforded by DNA/recombinant viral vector vaccines. However, these studies used as the challenge virus SHIV-89.6P, which is neutralizable, making it difficult to determine whether the observed protection was due to cellular immunity, humoral immunity, or a combination of both. In this study, we used a DNA prime/modified vaccinia virus Ankara boost regimen to immunize rhesus macaques against nearly all simian immunodeficiency virus (SIV) proteins. These animals were challenged intrarectally with pathogenic molecularly cloned SIVmac239, which is resistant to neutralization. The immunization regimen resulted in the induction of virus-specific CD8 ؉ and CD4 ؉ responses in all vaccinees. Although anamnestic neutralizing antibody responses against laboratoryadapted SIVmac251 developed after the challenge, no neutralizing antibodies against SIVmac239 were detectable. Vaccinated animals had significantly reduced peak viremia compared with controls (P < 0.01). However, despite the induction of virus-specific cellular immune responses and reduced peak viral loads, most animals still suffered from gradual CD4 depletion and progressed to disease.

Research paper thumbnail of Multispecific Vaccine-Induced Mucosal Cytotoxic T Lymphocytes Reduce Acute-Phase Viral Replication but Fail in Long-Term Control of Simian Immunodeficiency Virus SIVmac239

Journal of Virology, 2003

To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-speci... more To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-specific antibody, on the control of an immunodeficiency virus challenge, we vaccinated Mamu-A*01 ؉ macaques with constructs encoding a combination of CTL epitopes and full-length proteins (Tat, Rev, and Nef) by using a DNA prime/recombinant modified vaccinia virus Ankara (rMVA) boost regimen. The vaccination induced virusspecific CTL and CD4 ؉ helper T lymphocytes with CTL frequencies as high as 20,000/million peripheral blood mononuclear cells. The final rMVA vaccination, delivered intravenously, engendered long-lived mucosal CTL. At 16 weeks after the final rMVA vaccination, the vaccinees and naive, Mamu-A*01 ؉ controls were challenged intrarectally with SIVmac239. Massive early anamnestic cellular immune responses controlled acute-phase viral replication; however, the three vaccinees were unable to control virus replication in the chronic phase. The present study suggests that multispecific mucosal CTL, in the absence of neutralizing antibodies, can achieve a modicum of control over early viral replication but are unable to control chronic-phase viral replication after a high-dose mucosal challenge with a pathogenic simian immunodeficiency virus.

Research paper thumbnail of PATHOGENESIS AND IMMUNITY-Dominance of CD8 Responses Specific for Epitopes Bound by a Single Major Histocompatibility Complex Class I Molecule during the Acute Phase of Viral Infection

Journal of Virology, 2002

Research paper thumbnail of Escape in one of two cytotoxic T-lymphocyte epitopes bound by a high-frequency major histocompatibility complex class I molecule, Mamu-A* 02: a paradigm for virus evolution and persistence?

Journal of Virology, Nov 15, 2002

Mamu-A*01. Here we describe two novel epitopes derived from SIV, one from Gag (Gag 71-79 GY9), an... more Mamu-A*01. Here we describe two novel epitopes derived from SIV, one from Gag (Gag 71-79 GY9), and one from the Nef protein (Nef 159-167 YY9). Both epitopes are bound by the common macaque MHC class I molecule, Mamu-A*02. The sequences of these two eptiopes are consistent with the molecule's peptide-binding motif, which we have defined by elution of natural ligands from Mamu-A*02. Strikingly, we found evidence for the selection of escape variant viruses by CTL specific for Nef 159-167 YY9 in 6 of 6 Mamu-A*02-positive animals. In contrast, viral sequences encoding the Gag 71-79 GY9 epitope remained intact in each animal. This situation is reminiscent of Mamu-A*01-restricted CTL that recognize Tat 28-35 SL8, which reproducibly selects for escape variants during acute infection, and Gag 181-189 CM9, which does not. Differential selection by CTL may therefore be a paradigm of immunodeficiency virus infection.

Research paper thumbnail of Dominance of CD8 responses specific for epitopes bound by a single major histocompatibility complex class I molecule during the acute phase of viral infection

Journal of virology, Jan 15, 2002

Cytotoxic T-lymphocyte (CTL) responses are thought to control human immunodeficiency virus replic... more Cytotoxic T-lymphocyte (CTL) responses are thought to control human immunodeficiency virus replication during the acute phase of infection. Understanding the CD8+ T-cell immune responses early after infection may, therefore, be important to vaccine design. Analyzing these responses in humans is difficult since few patients are diagnosed during early infection. Additionally, patients are infected by a variety of viral subtypes, making it hard to design reagents to measure their acute-phase immune responses. Given the complexities in evaluating acute-phase CD8+ responses in humans, we analyzed these important immune responses in rhesus macaques expressing a common rhesus macaque major histocompatibility complex class I molecule (Mamu-A*01) for which we had developed a variety of immunological assays. We infected eight Mamu-A*01-positive macaques and five Mamu-A*01-negative macaques with the molecularly cloned virus SIVmac239 and determined all of the simian immunodeficiency virus-specific CD8+ T-cell responses against overlapping peptides spanning the entire virus. We also monitored the evolution of particular CD8+ T-cell responses by tetramer staining of peripheral lymphocytes as well as lymph node cells in situ. In this first analysis of the entire CD8+ immune response to autologous virus we show that between 2 and 12 responses are detected during the acute phase in each animal. CTL against the early proteins (Tat, Rev, and Nef) and against regulatory proteins Vif and Vpr dominated the acute phase. Interestingly, CD8+ responses against Mamu-A*01-restricted epitopes Tat28-35SL8 and Gag181-189CM9 were immunodominant in the acute phase. After the acute phase, however, this pattern of reactivity changed, and the Mamu-A*01-restricted response against the Gag181-189CM9 epitope became dominant. In most of the Mamu-A*01-positive macaques tested, CTL responses against epitopes bound by Mamu-A*01 dominated the CD8+ cellular immune response.