scholarly journals SLTRiP induces long lasting and protective T-cell memory response

2021 ◽  
Author(s):  
Agam Prasad Singh ◽  
Afshana Quadiri ◽  
Mohammad Kashif ◽  
Inderjeet Kalia
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Vaccine Development ◽  
Intracellular Cytokine Staining ◽  
T Cell Response ◽  
Parasite Development ◽  
Host Immune Responses ◽  
Immunological Mechanisms

Major developments have been made in the past many years to characterize and explore potential vaccine candidates that can induce host immune responses against parasite. These advances were based on the fact that the induction of host immune responses could effectively target parasite at different stages of its life cycle and thus, abrogate Plasmodium infections. The role of T-cells against malaria comes from initial studies on rodents showing these cells could inhibit parasite development during pre-erythrocytic stages. Since then, the importance of the cellular immune responses against malaria has been increasingly emphasized, especially for vaccine development against pre-erythrocytic stages. Previous work in our laboratory has confirmed that SLTRiP confers protection against the pre-erythrocytic stage of Plasmodium growth in rodents. Here we report that the protection is mainly due to cell mediated immune responses and Pb SLTRiP specific cellular memory responses could be efficiently recalled in mice challenged with P. berghei parasites even after a year following immunization. Our results thereby, highlight the role of the T cell response involved in protection. Characterization of T-cells by intracellular cytokine staining (ICS) revealed that the induced T cells were polyfunctional and involved in secretion of pro-inflammatory cytokines which mediate anti-parasitic activity. The findings contribute to our understanding of the immunological mechanisms underlying the protective vaccines.

scholarly journals Antigen-Specific T Cells and Cytokines Detection as Useful Tool for Understanding Immunity against Zoonotic Infections

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Annalisa Agnone ◽  
Alessandra Torina ◽  
Gesualdo Vesco ◽  
Sara Villari ◽  
Fabrizio Vitale ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Crucial Role ◽  
T Cell Subsets ◽  
Host Immune Responses ◽  
Zoonotic Infections ◽  
Immunological Mechanisms

Zoonoses include a broad range of diseases, that are becoming of great interest, due to the climate changing, that cause the adaptation of vectors to new niches and environments. Host immune responses play a crucial role in determining the outcome of infections, as documented by expansion of antigen-specific T cells during several zoonotic infections. Thus, understanding of the contribution of antigen-specific T-cell subsets in the host immune response is a powerful tool to evaluate the different immunological mechanisms involved in zoonotic infections and for the development of effective vaccines. In this paper we discuss the role of T cells in some eukaryotic and prokaryotic infectious models.

scholarly journals T Cell Immunity Evaluation and Immunodominant Epitope T Cell Receptor Identification of Severe Acute Respiratory Syndrome Coronavirus 2 Spike Glycoprotein in COVID-19 Convalescent Patients

2021 ◽  
Vol 9 ◽  
Author(s):  
Luo Li ◽  
Qian Chen ◽  
Xiaojian Han ◽  
Meiying Shen ◽  
Chao Hu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Severe Acute Respiratory Syndrome ◽  
Vaccine Development ◽  
Cell Receptor ◽  
T Cell Response ◽  
Cell Immunity ◽  
Ifn Γ

A better understanding of the role of T cells in the immune response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is helpful not only for vaccine development but also for the treatment of COVID-19 patients. In this study, we determined the existence of SARS-CoV-2-specific T cells in the blood of COVID-19 convalescents. Meanwhile, the specific T cell response in the non-RBD region was stronger than in the RBD region. We also found that SARS-CoV-2 S-specific reactive CD4+ T cells exhibited higher frequency than CD8+ T cells in recovered COVID-19 patients, with greater number of corresponding epitopes presented. Importantly, we isolated the SARS-CoV-2-specific CD4+ T cell receptors (TCRs) and inserted the TCRs into allogenic CD4+ T cells. These TCR-T cells can be activated by SARS-CoV-2 spike peptide and produce IFN-γ in vitro. These results might provide valuable information for the development of vaccines and new therapies against COVID-19.

scholarly journals Immunodominance of Adenovirus-Derived CD8+ T Cell Epitopes Interferes with the Induction of Transgene-Specific Immunity in Adenovirus-Based Immunization

2017 ◽  
Vol 91 (20) ◽  
Author(s):  
Dominik Schöne ◽  
Camilla Patrizia Hrycak ◽  
Sonja Windmann ◽  
Dennis Lapuente ◽  
Ulf Dittmer ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Vaccine Development ◽  
Interleukin 2 ◽  
T Cell Responses ◽  
T Cell Response ◽  
T Cell Epitopes ◽  
Content Type ◽  
Cell Responses

ABSTRACT Adenovirus (Ad)-based immunization is a popular approach in vaccine development, and Ad-based vectors are renowned for their potential to induce strong CD8+ T cell responses to the encoded transgene. Surprisingly, we previously found in the mouse Friend retrovirus (FV) model that Ad-based immunization did not induce CD8+ T cell responses to the FV Leader-Gag-derived immunodominant epitope GagL85–93. We show now that induction of GagL85–93-specific CD8+ T cells was highly effective when leader-Gag was delivered by plasmid DNA immunization, implying a role for Ad-derived epitopes in mediating unresponsiveness. By immunizing with DNA constructs encoding strings of GagL85–93 and the two Ad-derived epitopes DNA-binding protein418–426 (DBP418–426) and hexon486–494, we confirmed that Ad epitopes prevent induction of GagL85–93-specific CD8+ T cells. Interestingly, while DBP418–426 did not interfere with GagL85–93-specific CD8+ T cell induction, the H-2Dd-restricted hexon486–494 suppressed the CD8+ T cell response to the H-2Db-restricted GagL85–93 strongly in H-2b/d mice but not in H-2b/b mice. This finding indicates that competition occurs at the level of responding CD8+ T cells, and we could indeed demonstrate that coimmunization with an interleukin 2 (IL-2)-encoding plasmid restored GagL85–93-specific CD8+ T cell responses to epitope strings in the presence of hexon486–494. IL-2 codelivery did not restore GagL85–93 responsiveness in Ad-based immunization, however, likely due to the presence of further epitopes in the Ad vector. Our findings show that seemingly immunodominant transgene epitopes can be dominated by Ad-derived epitopes. These findings underline the importance of thorough characterization of vaccine vectors, and modifications of vectors or immunogens may be required to prevent impaired transgene-specific immune responses. IMPORTANCE Ad-based vectors are widely used in experimental preclinical and clinical immunization studies against numerous infectious agents, such as human immunodeficiency virus, Ebola virus, Plasmodium falciparum, or Mycobacterium tuberculosis. Preexisting immunity to Ad-based vectors is widely recognized as a hindrance to the widespread use of Ad-based vectors for immunizations in humans; however, our data show that an immune response to Ad-derived T cell epitopes can also result in loss or impairment of transgene-specific immune responses in prenaive vaccinees due to immune competition. Our results highlight that seemingly immunodominant epitopes may be affected by dominance of vector-derived epitopes, and modifications of the vector design or the immunogens employed in immunization may lead to more effective vaccines.

scholarly journals 596 Combining Bempegaldesleukin (CD122-preferential IL-2 pathway agonist) and NKTR-262 (TLR7/8 agonist) pairs local innate activation with systemic CD8+ T cell expansion to enhance anti-tumor immunity

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A626-A626
Author(s):  
Annah Rolig ◽  
Daniel Rose ◽  
Grace Helen McGee ◽  
Saul Kivimae ◽  
Werner Rubas ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Immune Responses ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
Cycle Phase ◽  
Tumor Cell Death ◽  
Specific Immunity

BackgroundTumor cell death caused by radiation therapy (RT) can trigger anti-tumor immune responses in part because dying cells release adjuvant factors that amplify and sustain DC and T cell responses. We previously demonstrated that bempegaldesleukin (BEMPEG:NKTR-214, a first-in-class CD122-preferential IL-2 pathway agonist), significantly enhanced the anti-tumor efficacy of RT through a T cell-dependent mechanism. Because RT can induce either immunogenic or tolerogenic cell death, depending on a multitude of factors (radiation dose, cell cycle phase, and tumor microenvironment), we hypothesized that providing a specific immunogenic adjuvant, like intratumoral NKTR-262, a novel toll-like receptor (TLR) 7/8 agonist, to the tumor site would further improve systemic tumor-specific immunity by promoting synergistic activation of local immunostimulatory innate immune responses. Therefore, we evaluated whether intratumoral NKTR-262, combined with systemic BEMPEG treatment would result in improved tumor-specific immunity and survival compared to BEMPEG combined with RT.MethodsTumor-bearing mice (CT26; EMT6) received BEMPEG (0.8 mg/kg; iv), RT (16 Gy x 1), and/or intratumoral NKTR-262 (0.5 mg/kg). Flow cytometry was used to evaluate CD4+ and CD8+ T cell activation status in the blood and tumor (7 days post-treatment). The contribution of specific immune subsets was determined by depletion of CD4+, CD8+, or NK cells. CD8+ T cell cytolytic activity was determined in vitro with an Incucyte assay. Data are representative of 1–2 independent experiments (n=5–14/group) and statistical significance was determined by 1-way ANOVA (p-value cut-off of 0.05).ResultsBEMPEG/NKTR-262 resulted in significantly improved survival compared to BEMPEG/RT. Both combination therapies were CD8+ T cell dependent. However, response to BEMPEG/NKTR-262 was characterized by a significant expansion of activated CD8+ T cells (GzmA+; Ki-67+; ICOS+; PD-1+) in the blood, which correlated with reduced tumor size (p<0.05). In the tumor, BEMPEG/NKTR-262 induced higher frequencies of GzmA+ CD8+ T cells exhibiting reduced expression of suppressive molecules (PD-1+, TIM-3+), compared to BEMPEG/RT. Additionally, CD8+ T cells isolated from BEMPEG/NKTR-262-treated tumors had greater cytolytic capacity than those from BEMPEG/RT-treated mice.ConclusionsCombining BEMPEG with NKTR-262 lead to a more robust expansion of activated CD8+ T cells compared to the BEMPEG/RT combination. Enhancement of the activated CD8+ T cell response in mice treated with NKTR-262 in combination with BEMPEG suggests that intratumoral TLR stimulation provides superior antigen presentation and costimulatory activity compared to RT. A clinical trial of BEMPEG/NKTR-262 for patients with metastatic solid tumors is in progress (NCT03435640).

scholarly journals Short-Lived Effector CD8 T Cells Induced by Genetically Attenuated Malaria Parasite Vaccination Express CD11c

2013 ◽  
Vol 81 (11) ◽  
pp. 4171-4181 ◽  
Author(s):  
Laura A. Cooney ◽  
Megha Gupta ◽  
Sunil Thomas ◽  
Sebastian Mikolajczak ◽  
Kimberly Y. Choi ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Inflammatory Cytokines ◽  
Plasmodium Yoelii ◽  
T Cell Response ◽  
Parasite Development ◽  
Effector Memory ◽  
Cell Phenotype ◽  
Effector Cells ◽  
Ifn Γ

ABSTRACTVaccination with a single dose of genetically attenuated malaria parasites can induce sterile protection against sporozoite challenge in the rodentPlasmodium yoeliimodel. Protection is dependent on CD8+T cells, involves perforin and gamma interferon (IFN-γ), and is correlated with the expansion of effector memory CD8+T cells in the liver. Here, we have further characterized vaccine-induced changes in the CD8+T cell phenotype and demonstrated significant upregulation of CD11c on CD3+CD8b+T cells in the liver, spleen, and peripheral blood. CD11c+CD8+T cells are predominantly CD11ahiCD44hiCD62L−, indicative of antigen-experienced effector cells. Followingin vitrorestimulation with malaria-infected hepatocytes, CD11c+CD8+T cells expressed inflammatory cytokines and cytotoxicity markers, including IFN-γ, tumor necrosis factor alpha (TNF-α), interleukin-2 (IL-2), perforin, and CD107a. CD11c−CD8+T cells, on the other hand, expressed negligible amounts of all inflammatory cytokines and cytotoxicity markers tested, indicating that CD11c marks multifunctional effector CD8+T cells. Coculture of CD11c+, but not CD11c−, CD8+T cells with sporozoite-infected primary hepatocytes significantly inhibited liver-stage parasite development. Tetramer staining for the immunodominant circumsporozoite protein (CSP)-specific CD8+T cell epitope demonstrated that approximately two-thirds of CSP-specific cells expressed CD11c at the peak of the CD11c+CD8+T cell response, but CD11c expression was lost as the CD8+T cells entered the memory phase. Further analyses showed that CD11c+CD8+T cells are primarily KLRG1+CD127−terminal effectors, whereas all KLRG1−CD127+memory precursor effector cells are CD11c−CD8+T cells. Together, these results suggest that CD11c marks a subset of highly inflammatory, short-lived, antigen-specific effector cells, which may play an important role in eliminating infected hepatocytes.

scholarly journals Alphavirus-based hepatitis C virus therapeutic vaccines: can universal helper epitopes enhance HCV-specific cytotoxic T lymphocyte responses?

2019 ◽  
Vol 7 ◽  
pp. 251513551987467
Author(s):  
Georgia Koutsoumpli ◽  
Peng Peng Ip ◽  
Ilona Schepel ◽  
Baukje Nynke Hoogeboom ◽  
Annemarie Boerma ◽  
...  
Keyword(s):  
T Cells ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
T Cell ◽  
Immune Responses ◽  
Semliki Forest Virus ◽  
Intracellular Cytokine Staining ◽  
Target Antigen ◽  
Optimal Dosage ◽  
Therapeutic Vaccines

Background: Antigen-specific T cell immune responses play a pivotal role in resolving acute and chronic hepatitis C virus (HCV) infections. Currently, no prophylactic or therapeutic vaccines against HCV are available. We previously demonstrated the preclinical potency of therapeutic HCV vaccines based on recombinant Semliki Forest virus (SFV) replicon particles. However, clinical trials do not always meet the high expectations of preclinical studies, thus, optimization of vaccine strategies is crucial. In efforts to further increase the frequency of HCV-specific immune responses in the candidate SFV-based vaccines, the authors assessed whether inclusion of three strong, so-called universal helper T cell epitopes, and an endoplasmic reticulum localization, and retention signal (collectively termed sigHELP-KDEL cassette) could enhance HCV-specific immune responses. Methods: We included the sigHELP-KDEL cassette in two of the candidate SFV-based HCV vaccines, targeting NS3/4A and NS5A/B proteins. We characterized the new constructs in vitro for the expression and stability of the transgene-encoded proteins. Their immune efficacy with respect to HCV-specific immune responses in vivo was compared with the parental SFV vaccine expressing the corresponding HCV antigen. Further characterization of the functionality of the HCV-specific CD8+ T cells was assessed by surface and intracellular cytokine staining and flow cytometry analysis. Results: Moderate, but significantly, enhanced frequencies of antigen-specific immune responses were achieved upon lower/suboptimal dosage immunization. In optimal dosage immunization, the inclusion of the cassette did not further increase the frequencies of HCV-specific CD8+ T cells when compared with the parental vaccines and the frequencies of effector and memory populations were identical. Conclusion: We hypothesize that the additional effect of the sigHELP-KDEL cassette in SFV-based vaccines depends on the immunogenicity, nature, and stability of the target antigen expressed by the vaccine.

scholarly journals Vaccination against RhoC induces long-lasting immune responses in patients with prostate cancer: results from a phase I/II clinical trial

2020 ◽  
Vol 8 (2) ◽  
pp. e001157
Author(s):  
Juliane Schuhmacher ◽  
Sonja Heidu ◽  
Torben Balchen ◽  
Jennifer Rebecca Richardson ◽  
Camilla Schmeltz ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Phase I ◽  
Cell Response ◽  
Small Gtpase ◽  
T Cell Response ◽  
Effector Memory ◽  
Tolerability Profile

BackgroundPeptide-based vaccination is a rational option for immunotherapy of prostate cancer. In this first-in-man phase I/II study, we assessed the safety, tolerability and immunological impact of a synthetic long peptide vaccine targeting Ras homolog gene family member C (RhoC) in patients with prostate cancer. RhoC is a small GTPase overexpressed in advanced solid cancers, metastases and cancer stem cells.MethodsTwenty-two patients who had previously undergone radical prostatectomy received subcutaneous injections of 0.1 mg of a single RhoC-derived 20mer peptide emulsified in Montanide ISA-51 every 2 weeks for the first six times, then five times every 4 weeks for a total treatment time of 30 weeks. The drug safety and vaccine-specific immune responses were assessed during treatment and thereafter within a 13-month follow-up period. Serum level of prostate-specific antigen was measured up to 26 months postvaccination.ResultsMost patients (18 of 21 evaluable) developed a strong CD4 T cell response against the vaccine, which lasted at least 10 months following the last vaccination. Three promiscuouslypresented HLA-class II epitopes were identified. Vaccine-specific CD4 T cells were polyfunctional and effector memory T cells that stably expressed PD-1 (CD279) and OX-40 (CD134), but not LAG-3 (CD223). One CD8 T cell response was detected in addition. The vaccine was well tolerated and no treatment-related adverse events of grade ≥3 were observed.ConclusionTargeting of RhoC induced a potent and long-lasting T cell immunity in the majority of the patients. The study demonstrates an excellent safety and tolerability profile. Vaccination against RhoC could potentially delay or prevent tumor recurrence and metastasis formation.Trial registration numberNCT03199872.

scholarly journals Sustained Specific and Cross-Reactive T Cell Responses to Zika and Dengue Virus NS3 in West Africa

2018 ◽  
Vol 92 (7) ◽  
Author(s):  
Bobby Brooke Herrera ◽  
Wen-Yang Tsai ◽  
Charlotte A. Chang ◽  
Donald J. Hamel ◽  
Wei-Kung Wang ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
Dengue Virus ◽  
Zika Virus ◽  
Cell Response ◽  
Vaccine Development ◽  
T Cell Responses ◽  
T Cell Response ◽  
Zikv Infection ◽  
Cell Responses

ABSTRACT Recent studies on the role of T cells in Zika virus (ZIKV) infection have shown that T cell responses to Asian ZIKV infection are important for protection, and that previous dengue virus (DENV) exposure amplifies the protective T cell response to Asian ZIKV. Human T cell responses to African ZIKV infection, however, remain unexplored. Here, we utilized the modified anthrax toxin delivery system to develop a flavivirus enzyme-linked immunosorbent spot (ELISPOT) assay. Using human ZIKV and DENV samples from Senegal, West Africa, our results demonstrate specific and cross-reactive T cell responses to nonstructural protein 3 (NS3). Specifically, we found that T cell responses to NS3 protease are ZIKV and DENV specific, but responses to NS3 helicase are cross-reactive. Sequential sample analyses revealed immune responses sustained many years after infection. These results have important implications for African ZIKV/DENV vaccine development, as well as for potential flavivirus diagnostics based on T cell responses. IMPORTANCE The recent Zika virus (ZIKV) epidemic in Latin America and the associated congenital microcephaly and Guillain-Barré syndrome have raised questions as to why we have not recognized these distinct clinical diseases in Africa. The human immunologic response to ZIKV and related flaviviruses in Africa represents a research gap that may shed light on the mechanisms contributing to protection. The goal of our study was to develop an inexpensive assay to detect and characterize the T cell response to African ZIKV and DENV. Our data show long-term specific and cross-reactive human immune responses against African ZIKV and DENV, suggesting the usefulness of a diagnostic based on the T cell response. Additionally, we show that prior flavivirus exposure influences the magnitude of the T cell response. The identification of immune responses to African ZIKV and DENV is of relevance to vaccine development.

scholarly journals Role of Exosomes in the Regulation of T-cell Mediated Immune Responses and in Autoimmune Disease

Cells ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 154 ◽  
Author(s):  
Alberto Anel ◽  
Ana Gallego-Lleyda ◽  
Diego de Miguel ◽  
Javier Naval ◽  
Luis Martínez-Lostao
Keyword(s):  
T Cells ◽  
T Cell ◽  
Autoimmune Disease ◽  
Immune Responses ◽  
T Regulatory Cells ◽  
Inflammatory Diseases ◽  
Activated T Cells ◽  
Regulatory Processes ◽  
Activation Induced Cell Death

: T-cell mediated immune responses should be regulated to avoid the development of autoimmune or chronic inflammatory diseases. Several mechanisms have been described to regulate this process, namely death of overactivated T cells by cytokine deprivation, suppression by T regulatory cells (Treg), induction of expression of immune checkpoint molecules such as CTLA-4 and PD-1, or activation-induced cell death (AICD). In addition, activated T cells release membrane microvesicles called exosomes during these regulatory processes. In this review, we revise the role of exosome secretion in the different pathways of immune regulation described to date and its importance in the prevention or development of autoimmune disease. The expression of membrane-bound death ligands on the surface of exosomes during AICD or the more recently described transfer of miRNA or even DNA inside T-cell exosomes is a molecular mechanism that will be analyzed.

Identification of the AAV2 Capsid CD8+ T Cell Epitope in C57BL/6 Mice.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3188-3188
Author(s):  
Denise E. Sabatino ◽  
Federico Mingozzi ◽  
Haifeng Chen ◽  
Peter Colosi ◽  
Hildegund C.J. Ertl ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Capsid Protein ◽  
Cd8 T Cells ◽  
Cell Epitope ◽  
T Cell Response ◽  
Cd8 Cells ◽  
Media Control ◽  
Ifn Γ

Abstract Recently, a clinical trial for adeno-associated virus serotype 2 (AAV2) mediated liver directed gene transfer of human Factor IX to subjects with severe hemophilia B revealed that two patients developed transient asymptomatic transaminitis following vector administration. Immunology studies in the second patient demonstrated a transient T cell response to AAV2 capsid peptides suggesting that the immune response to the AAV capsid may be related to the transient transaminitis. We hypothesized that the observations made in the human subjects were due to a CD8 T cell response to AAV2 capsid protein. Preclinical studies in mice and dogs, which are not naturally infected by wild type AAV2 viruses, did not predict these findings in the clinical study. Thus, we developed a mouse model in which we were able to mimic this phenomenon (Blood 102:493a). In an effort to further characterize the immune responses to AAV2 capsid proteins in this mouse model, we identified the T cell epitope in the AAV capsid protein recognized by murine C57Bl/6 CD8 T cells. A peptide library of AAV2 VP1 capsid peptides (n=145) that were synthesized as 15mers overlapping by 10 amino acids were divided into 6 pools each containing 24–25 peptides. C57Bl/6 mice were immunized intramuscularly with an adenovirus expressing AAV2 capsid protein. Nine days later the spleen was harvested and intracellular cytokine staining (ICS) was used to assess release of IFN-γ from CD8 T cells in response to 6 AAV2 capsid peptide pools. ICS demonstrated CD8 cells from mice immunized with Ad-AAV2 produced IFN-γ (3.5% of the CD8 cells) in response to Pool F (amino acid 119–145) while no IFN-γ release in CD8 cells was detected with Pool A to E (mean 0.28%±0.25%) compared to the media control (0.16%). This detection of IFN-γ release from CD8 T cells indicates a specific proliferation to a peptide(s) within this peptide pool (Pool F). A matrix approach was used to further define which peptide(s) contained the immunodominant epitope. Eleven small peptide pools of Pool F were created in which each peptide was represented in 2 pools. ICS of splenocytes from immunized (Ad-AAV2 capsid) C57Bl/6 mice demonstrated IFN-γ response from CD8 cells to 3 of the matrix pools corresponding to peptide 140 (PEIQYTSNYNKSVNV) and 141 (TSNYNKSVNVDFTVD) compared with media controls. To determine the exact peptide sequence that binds to the MHC Class I molecule, 9 amino acid peptides (n=7) were created that overlap peptide 140 and 141. Peptide SNYNKSVNV showed positive staining for both CD8 and IFN- γ(3.2%) compared with the six other peptides (0.14%±0.08%), media control (0.08%) and mice that were not immunized (0.11%). This epitope lies in the C terminus of the AAV2 VP1 capsid protein. Current studies using strains of mice with different MHC H2 haplotypes will allow us to determine which of the C57Bl/6 MHC alleles the epitope binds. These findings will provide us with a powerful tool for assessing immune responses to AAV capsid in the context of gene therapy. Specifically, they will allow us to determine how long immunologically detectable capsid sequences persist in an animal injected with AAV vectors. This in turn will provide a basis for a clinical study in which subjects are transiently immunosuppressed, from the time of vector injection until capsid epitopes are no longer detectable by the immune system.

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