scholarly journals Screening HLA-A-restricted T cell epitopes of SARS-CoV-2 and the induction of CD8+ T cell responses in HLA-A transgenic mice

2021 ◽  
Author(s):  
Xiaoxiao Jin ◽  
Yan Ding ◽  
Shihui Sun ◽  
Xinyi Wang ◽  
Zining Zhou ◽  
...  
Keyword(s):  
T Cell ◽  
Transgenic Mice ◽  
T Cell Responses ◽  
Poly I:C ◽  
T Cell Epitopes ◽  
Wild Type ◽  
Cell Responses ◽  
Asian Populations ◽  
Donor Pbmcs

AbstractSince severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-specific T cells have been found to play essential roles in host immune protection and pathology in patients with coronavirus disease 2019 (COVID-19), this study focused on the functional validation of T cell epitopes and the development of vaccines that induce specific T cell responses. A total of 120 CD8+ T cell epitopes from the E, M, N, S, and RdRp proteins were functionally validated. Among these, 110, 15, 6, 14, and 12 epitopes were highly homologous with SARS-CoV, OC43, NL63, HKU1, and 229E, respectively; in addition, four epitopes from the S protein displayed one amino acid that was distinct from the current SARS-CoV-2 variants. Then, 31 epitopes restricted by the HLA-A2 molecule were used to generate peptide cocktail vaccines in combination with Poly(I:C), R848 or poly (lactic-co-glycolic acid) nanoparticles, and these vaccines elicited robust and specific CD8+ T cell responses in HLA-A2/DR1 transgenic mice as well as wild-type mice. In contrast to previous research, this study established a modified DC-peptide-PBL cell coculture system using healthy donor PBMCs to validate the in silico predicted epitopes, provided an epitope library restricted by nine of the most prevalent HLA-A allotypes covering broad Asian populations, and identified the HLA-A restrictions of these validated epitopes using competitive peptide binding experiments with HMy2.CIR cell lines expressing the indicated HLA-A allotype, which initially confirmed the in vivo feasibility of 9- or 10-mer peptide cocktail vaccines against SARS-CoV-2. These data will facilitate the design and development of vaccines that induce antiviral CD8+ T cell responses in COVID-19 patients.

scholarly journals Screening of HLA-A restricted T cell epitopes of SARS-CoV-2 and induction of CD8+ T cell responses in HLA-A transgenic mice

2021 ◽  
Author(s):  
Xiaoxiao Jin ◽  
Ding Yan ◽  
Sun Shihui ◽  
Xinyi Wang ◽  
Zining Zhou ◽  
...  
Keyword(s):  
T Cell ◽  
Transgenic Mice ◽  
Cell Epitope ◽  
T Cell Responses ◽  
Poly I:C ◽  
T Cell Epitopes ◽  
Cell Responses ◽  
Mhc Class I Molecule ◽  
Healthy Donors ◽  
Epitope Vaccines

AbstractWhile SARS-CoV-2-specific T cells have been characterized to play essential roles in host immune protection in COVID-19 patients, few researches focus on the functional validation of T cell epitopes and development of vaccines inducing specific T cell responses. In this study, 120 CD8+ T cell epitopes from E, M, N, S and RdRp proteins of SARS-CoV-2 were validated by on-silicon prediction, DC-peptide-PBL costimulation with healthy donors’ PBMCs and HLA-A molecule competitive binding experiments. Among them, 110, 15, 6, 14 and 12 epitopes were highly homologous with SARS-CoV, OC43, NL63, HKU1, and 229E, respectively. Thirty-one epitopes restricted by HLA-A2 molecule were used to generate peptide cocktail vaccines in combination with Poly(I:C), R848 or polylactic-co-glycolic acid nanoparticles, which elicited robust specific CD8+ T cell responses in wild-type and HLA-A2/DR1 transgenic mice. Seven of the 31 epitopes were found to be cross-presented by HLA-A2 and H-2K/Db molecules. These data have provided a library of SARS-CoV-2 CD8+ T cell epitopes which restricted by a series of high-frequency HLA-A allotypes and covered broad population in Asia, and initially confirmed the feasibility of human MHC class I molecule-restricted SARS-CoV2 epitope peptide cocktail vaccines, thus will facilitate the development of T cell epitope vaccines and specific cellular function detection kits.

scholarly journals Role of the Mannose Receptor in a Murine Model of Cryptococcus neoformans Infection

2008 ◽  
Vol 76 (6) ◽  
pp. 2362-2367 ◽  
Author(s):  
Jennifer M. Dan ◽  
Ryan M. Kelly ◽  
Chrono K. Lee ◽  
Stuart M. Levitz
Keyword(s):  
T Cell ◽  
Cryptococcus Neoformans ◽  
Cell Function ◽  
Ex Vivo ◽  
T Cell Responses ◽  
Mannose Receptor ◽  
Wild Type ◽  
Cell Responses

ABSTRACT Cryptococcus neoformans is an encapsulated fungal pathogen with a predilection to infect persons with suppressed T-cell function. Cryptococcal mannoproteins (MP) are highly mannosylated antigens which elicit T-cell responses in infected mice and in convalescent patients. Key to the immunogenicity of MP is its capacity to bind to the conserved mannose receptor (MR), CD206, on dendritic cells (DCs). To test the role of the MR in the immune response to C. neoformans, wild-type and MR knockout (MR KO) mice were compared by using in vivo and ex vivo models of cryptococcosis. Following a pulmonary challenge with C. neoformans, MR KO mice died significantly faster than wild-type mice and had higher lung fungal burdens after 4 weeks of infection. Uptake of MP was similar when DCs obtained from wild-type and MR KO mice were compared. Additionally, MP did not upregulate the maturation markers major histocompatibility complex class II, CD86, and CD40 in either wild-type or MR KO DCs. However, MP stimulated lymphoproliferation in CD4+ T cells obtained from the peripheral lymph nodes of infected wild-type but not MR KO mice. These studies demonstrate a nonredundant role for the MR in the development of CD4+ T-cell responses to MP and protection from C. neoformans.

scholarly journals De Novo Generation of Escape Variant-Specific CD8+ T-Cell Responses following Cytotoxic T-Lymphocyte Escape in Chronic Human Immunodeficiency Virus Type 1 Infection

2005 ◽  
Vol 79 (20) ◽  
pp. 12952-12960 ◽  
Author(s):  
Todd M. Allen ◽  
Xu G. Yu ◽  
Elizabeth T. Kalife ◽  
Laura L. Reyor ◽  
Mathias Lichterfeld ◽  
...  
Keyword(s):  
T Cell ◽  
De Novo ◽  
Cytotoxic T Lymphocyte ◽  
T Cell Responses ◽  
T Cell Epitopes ◽  
Wild Type ◽  
Cell Responses ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) evades CD8+ T-cell responses through mutations within targeted epitopes, but little is known regarding its ability to generate de novo CD8+ T-cell responses to such mutants. Here we examined gamma interferon-positive, HIV-1-specific CD8+ T-cell responses and autologous viral sequences in an HIV-1-infected individual for more than 6 years following acute infection. Fourteen optimal HIV-1 T-cell epitopes were targeted by CD8+ T cells, four of which underwent mutation associated with dramatic loss of the original CD8+ response. However, following the G357S escape in the HLA-A11-restricted Gag349-359 epitope and the decline of wild-type-specific CD8+ T-cell responses, a novel CD8+ T-cell response equal in magnitude to the original response was generated against the variant epitope. CD8+ T cells targeting the variant epitope did not exhibit cross-reactivity against the wild-type epitope but rather utilized a distinct T-cell receptor Vβ repertoire. Additional studies of chronically HIV-1-infected individuals expressing HLA-A11 demonstrated that the majority of the subjects targeted the G357S escape variant of the Gag349-359 epitope, while the wild-type consensus sequence was significantly less frequently recognized. These data demonstrate that de novo responses against escape variants of CD8+ T-cell epitopes can be generated in chronic HIV-1 infection and provide the rationale for developing vaccines to induce CD8+ T-cell responses directed against both the wild-type and variant forms of CD8 epitopes to prevent the emergence of cytotoxic T-lymphocyte escape variants.

scholarly journals T-Cell Recognition of the HspX Protein of Mycobacterium tuberculosis Correlates with Latent M. tuberculosis Infection but Not with M. bovis BCG Vaccination

2007 ◽  
Vol 75 (6) ◽  
pp. 2914-2921 ◽  
Author(s):  
Annemieke Geluk ◽  
May Young Lin ◽  
Krista E. van Meijgaarden ◽  
Eliane M. S. Leyten ◽  
Kees L. M. C. Franken ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
T Cell Responses ◽  
Cell Recognition ◽  
T Cell Epitopes ◽  
Bcg Vaccination ◽  
T Cell Recognition ◽  
Cell Responses

ABSTRACT During stationary growth or in vitro conditions mimicking relevant aspects of latency, the HspX protein (Rv2031c) is specifically upregulated by Mycobacterium tuberculosis. In this study we compared T-cell responses against HspX and the secreted M. tuberculosis protein Ag85B (Rv1886c) in tuberculosis (TB) patients, tuberculin skin test-positive individuals, M. bovis BCG-vaccinated individuals, and healthy negative controls. Gamma interferon responses to HspX were significantly higher in M. tuberculosis-exposed individuals than in M. tuberculosis-unexposed BCG vaccinees. In contrast, no such differences were found with respect to T-cell responses against Ag85B. Therefore, BCG-based vaccines containing relevant fragments of HspX may induce improved responses against this TB latency antigen. To identify relevant major histocompatibility complex class I- and class II-restricted HspX-specific T-cell epitopes, we immunized HLA-A2/Kb and HLA-DR3.Ab0 transgenic (tg) mice with HspX. Two new T-cell epitopes were identified, p91-105 and p31-50, restricted via HLA-A*0201 and HLA-DRB1*0301, respectively. These epitopes were recognized by human T cells as well, underlining the relevance of HspX T-cell recognition both in vivo and in vitro. In line with the data in humans, BCG immunization of both tg strains did not lead to T-cell responses against HspX-derived epitopes, whereas nonlatency antigens were efficiently recognized. These data support the notion that BCG vaccination per se does not induce T-cell responses against the latency antigen, HspX. Thus, we suggest that subunit vaccines incorporating HspX and/or other latency antigens, as well as recombinant BCG strains expressing latency antigens need to be considered as new vaccines against TB.

scholarly journals Mice transgenic for a soluble form of murine CTLA-4 show enhanced expansion of antigen-specific CD4+ T cells and defective antibody production in vivo.

1994 ◽  
Vol 179 (3) ◽  
pp. 809-817 ◽  
Author(s):  
F Ronchese ◽  
B Hausmann ◽  
S Hubele ◽  
P Lane
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Transgenic Mice ◽  
T Cell Activation ◽  
Antibody Production ◽  
T Cell Responses ◽  
Soluble Form ◽  
Cell Responses

CD4+ T cell responses were analyzed in transgenic mice expressing a soluble form of murine CTLA-4, mCTLA4-H gamma 1, which blocks the interaction of the T cell activation molecules CD28 and CTLA-4 with their costimulatory ligands. Consistent with previous reports (Linsley, P. S., P. M. Wallace, J. Johnson, M. G. Gibson, J. L. Greene, J. A. Ledbetter, C. Singh, and M. A. Tepper. 1992. Science (Wash. DC). 257:792), T cell-dependent antibody production was profoundly inhibited in mCTLA4-H gamma 1 transgenic mice immunized with a protein antigen. Surprisingly, however, transgenic mice could generate quantitatively and qualitatively normal primary T cell responses, as measured by limiting dilution assays and lymphokine production. In addition, in vivo expansion of antigen-specific T cells after secondary or tertiary immunization was enhanced in mCTLA4-H gamma 1 transgenics as compared with normal mice. Although unable to deliver cognate help to B cells in vivo, T cells from mCTLA4-H gamma 1 transgenic mice were not anergic as they could help B cells to produce specific antibodies when adoptively transferred into nude hosts. Taken together, these data suggest that the engagement of CD28 and/or CTLA-4 may not be required for the induction of T cell responses, as is currently understood, but rather for the expression of T cell effector function such as the delivery of T cell help to B cells.

scholarly journals Phagocytes produce prostaglandin E2 in response to cytosolic Listeria monocytogenes

2021 ◽  
Vol 17 (9) ◽  
pp. e1009493
Author(s):  
Courtney E. McDougal ◽  
Zachary T. Morrow ◽  
Tighe Christopher ◽  
Seonyoung Kim ◽  
Drake Carter ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
T Cell ◽  
T Cell Responses ◽  
Prostaglandin E ◽  
Type I ◽  
Wild Type ◽  
Cell Responses ◽  
T Cell Priming ◽  
Cox 2

Listeria monocytogenes is an intracellular bacterium that elicits robust CD8+ T-cell responses. Despite the ongoing development of L. monocytogenes-based platforms as cancer vaccines, our understanding of how L. monocytogenes drives robust CD8+ T-cell responses remains incomplete. One overarching hypothesis is that activation of cytosolic innate pathways is critical for immunity, as strains of L. monocytogenes that are unable to access the cytosol fail to elicit robust CD8+ T-cell responses and in fact inhibit optimal T-cell priming. Counterintuitively, however, activation of known cytosolic pathways, such as the inflammasome and type I IFN, lead to impaired immunity. Conversely, production of prostaglandin E2 (PGE2) downstream of cyclooxygenase-2 (COX-2) is essential for optimal L. monocytogenes T-cell priming. Here, we demonstrate that vacuole-constrained L. monocytogenes elicit reduced PGE2 production compared to wild-type strains in macrophages and dendritic cells ex vivo. In vivo, infection with wild-type L. monocytogenes leads to 10-fold increases in PGE2 production early during infection whereas vacuole-constrained strains fail to induce PGE2 over mock-immunized controls. Mice deficient in COX-2 specifically in Lyz2+ or CD11c+ cells produce less PGE2, suggesting these cell subsets contribute to PGE2 levels in vivo, while depletion of phagocytes with clodronate abolishes PGE2 production completely. Taken together, this work demonstrates that optimal PGE2 production by phagocytes depends on L. monocytogenes access to the cytosol, suggesting that one reason cytosolic access is required to prime CD8+ T-cell responses may be to facilitate production of PGE2.

scholarly journals Influenza H1 Mosaic Hemagglutinin Vaccine Induces Broad Immunity and Protection in Mice

Vaccines ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 195 ◽  
Author(s):  
Brigette N. Corder ◽  
Brianna L. Bullard ◽  
Jennifer L. DeBeauchamp ◽  
Natalia A. Ilyushina ◽  
Richard J. Webby ◽  
...  
Keyword(s):  
T Cell ◽  
Influenza Vaccine ◽  
Protective Immunity ◽  
Influenza A ◽  
T Cell Responses ◽  
Antibody Responses ◽  
T Cell Epitopes ◽  
Wild Type ◽  
Cell Responses ◽  
Universal Influenza Vaccine

Annually, influenza A virus (IAV) infects ~5–10% of adults and 20–30% of children worldwide. The primary resource to protect against infection is by vaccination. However, vaccination only induces strain-specific and transient immunity. Vaccine strategies that induce cross-protective immunity against the broad diversity of IAV are needed. Here we developed and tested a novel mosaic H1 HA immunogen. The mosaic immunogen was optimized in silico to include the most potential B and T cell epitopes (PBTE) across a diverse population of human H1 IAV. Phylogenetic analysis showed that the mosaic HA localizes towards the non-pandemic 2009 strains which encompasses the broadest diversity in the H1 IAV population. We compared the mosaic H1 immunogen to wild-type HA immunogens and the commercial inactivated influenza vaccine, Fluzone. When analyzed by ELISA, the mosaic immunogen induced stronger antibody responses against all four diverse H1 HA proteins. When analyzing T cell responses, again the mosaic immunogen induced stronger cellular immunity against all 4 diverse HA strains. Not only was the magnitude of T cell responses strongest in mosaic immunized mice, the number of epitopes recognized was also greater. The mosaic vaccinated mice showed strong cross-protection against challenges with three divergent IAV strains. These data show that the mosaic immunogen induces strong cross-protective immunity and should be investigated further as a universal influenza vaccine.

scholarly journals T Cell Epitope Screening of Epstein-Barr Virus Fusion Protein gB

2021 ◽  
Vol 95 (10) ◽  
Author(s):  
Haiwen Chen ◽  
Xiao Zhang ◽  
Shanshan Zhang ◽  
Xiaobing Duan ◽  
Tong Xiang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Vaccine Development ◽  
T Cell Responses ◽  
Target Antigen ◽  
T Cell Epitopes ◽  
Cell Responses ◽  
Ebv Infection ◽  
Ebv Reactivation

ABSTRACT Glycoprotein B (gB) is an essential fusion protein for Epstein-Barr virus (EBV) infection of both B cells and epithelial cells and is thus a promising target antigen for a prophylactic vaccine to prevent or reduce EBV-associated disease. T cell responses play key roles in the control of persistent EBV infection and the efficacy of a vaccine. However, to date, T cell responses to gB have been characterized for only a limited number of human leukocyte antigen (HLA) alleles. Here, we screened gB T cell epitopes in 23 healthy EBV carriers and 10 patients with nasopharyngeal cancer (NPC) using a peptide library spanning the entire gB sequence. We identified 12 novel epitopes in the context of seven new HLA restrictions that are common in Asian populations. Two epitopes, gB214–223 and gB840–849, restricted by HLA-B*58:01 and -B*38:02, respectively, elicited specific CD8+ T cell responses to inhibit EBV-driven B cell transformation. Interestingly, gB-specific CD8+ T cells were more frequent in healthy viral carriers with EBV reactivation than in those without EBV reactivation, indicating that EBV reactivation in vivo stimulates both humoral (VCA-gp125-IgA) and cellular responses to gB. We further found that most gB epitopes are conserved among different EBV strains. Our study broadens the diversity and HLA restrictions of gB epitopes and suggests that gB is a common target of T cell responses in healthy viral carriers with EBV reactivation. In particular, the precisely mapped and conserved gB epitopes provide valuable information for prophylactic vaccine development. IMPORTANCE T cells are crucial for the control of persistent EBV infection and the development of EBV-associated diseases. The EBV gB protein is essential for virus entry into B cells and epithelial cells and is thus a target antigen for vaccine development. Understanding T cell responses to gB is important for subunit vaccine design. Here, we comprehensively characterized T cell responses to full-length gB. Our results expand the available gB epitopes and HLA restrictions, particularly those common in Asian populations. Furthermore, we showed that gB-specific CD8+ T cells inhibit B cell transformation ex vivo and that gB-specific CD8+ T cell responses in vivo may be associated with intermittent EBV reactivation in asymptomatic viral carriers. These gB epitopes are highly conserved among geographically separated EBV strains. Precisely mapped and conserved T cell epitopes may contribute to immune monitoring and the development of a gB subunit vaccine.

scholarly journals Prostaglandin E2 induction by cytosolic Listeria monocytogenes in phagocytes is necessary for optimal T-cell priming

2021 ◽  
Author(s):  
Courtney E McDougal ◽  
Zachary T Morrow ◽  
Seonyoung Kim ◽  
Drake Carter ◽  
David M Stevenson ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
T Cell ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Type I ◽  
Wild Type ◽  
Cell Responses ◽  
T Cell Priming ◽  
Cox 2

Listeria monocytogenes is an intracellular bacterium that elicits robust CD8 + T-cell responses. Despite the ongoing development of L. monocytogenes -based platforms as cancer vaccines, our understanding of how L. monocytogenes drives robust CD8 + T-cell responses remains incomplete. One overarching hypothesis is that activation of cytosolic innate pathways is critical for immunity, as strains of L. monocytogenes that are unable to access the cytosol fail to elicit robust CD8 + T-cell responses and in fact inhibit optimal T-cell priming. Counterintuitively, however, activation of known cytosolic pathways, such as the inflammasome and type I IFN, lead to impaired immunity. Here, we describe a cytosol-dependent response that is critical for immunity to L. monocytogenes , namely production of prostaglandin E 2 (PGE 2 ) downstream of cyclooxygenase-2 (COX-2). Vacuole-constrained L. monocytogenes elicit reduced PGE 2 production compared to wild-type strains in macrophages and dendritic cells ex vivo . In vivo, infection with wild-type L. monocytogenes leads to 10-fold increases in PGE 2 production early during infection whereas vacuole-constrained strains fail to induce PGE 2 over mock-immunized controls. Mice deficient in COX-2 specifically in Lyz2 + or CD11c + cells produce less PGE 2 , suggesting these cell subsets contribute to PGE 2 levels in vivo, while depletion of phagocytes with clodronate abolishes PGE 2 production completely . Taken together, this work identifies the first known cytosol-dependent innate immune response critical for generating CD8 + T-cell responses to L. monocytogenes, suggesting that one reason cytosolic access is required to prime CD8 + T-cell responses may be due to induction of PGE 2 .

Generation of tissue-specific H-2Kd transgenic mice for the study of Kd-restricted malaria epitope-specific CD8+ T-cell responses in vivo

2013 ◽  
Vol 387 (1-2) ◽  
pp. 254-261 ◽  
Author(s):  
Jing Huang ◽  
Xiangming Li ◽  
Kenji Kohno ◽  
Masahiko Hatano ◽  
Takeshi Tokuhisa ◽  
...  
Keyword(s):  
T Cell ◽  
Transgenic Mice ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Tissue Specific ◽  
Cell Responses
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