scholarly journals Protective Vaccine Efficacy of the Complete Form of PPE39 Protein from Mycobacterium tuberculosis Beijing/K Strain in Mice

2017 ◽  
Vol 24 (11) ◽  
Author(s):  
Ahreum Kim ◽  
Yun-Gyoung Hur ◽  
Sunwha Gu ◽  
Sang-Nae Cho
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Vaccine Development ◽  
Protective Efficacy ◽  
Interleukin 2 ◽  
T Cell Epitopes ◽  
Content Type ◽  
Complete Form ◽  
Ifn Γ

ABSTRACT The aim of this study was to evaluate the protective efficacy of MTBK_24820, a complete form of PPE39 protein derived from a predominant Beijing/K strain of Mycobacterium tuberculosis in South Korea. Mice were immunized with MTKB_24820, M. bovis Bacilli Calmette-Guérin (BCG), or adjuvant prior to a high-dosed Beijing/K strain aerosol infection. After 4 and 9 weeks, bacterial loads were determined and histopathologic and immunologic features in the lungs and spleens of the M. tuberculosis-infected mice were analyzed. Putative immunogenic T-cell epitopes were examined using synthetic overlapping peptides. Successful immunization of MTBK_24820 in mice was confirmed by increased IgG responses (P < 0.05) and recalled gamma interferon (IFN-γ), interleukin-2 (IL-2), IL-6, and IL-17 responses (P < 0.05 or P < 0.01) to MTBK_24820. After challenge with the Beijing/K strain, an approximately 0.5 to 1.0 log10 reduction in CFU in lungs and fewer lung inflammation lesions were observed in MTBK_24820-immunized mice compared to those for control mice. Moreover, MTBK_24820 immunization elicited significantly higher numbers of CD4+ T cells producing protective cytokines, such as IFN-γ and IL-17, in lungs and spleens (P < 0.01) and CD4+ multifunctional T cells producing IFN-γ, tumor necrosis factor alpha (TNF-α), and/or IL-17 (P < 0.01) than in control mice, suggesting protection comparable to that of BCG against the hypervirulent Beijing/K strain. The dominant immunogenic T-cell epitopes that induced IFN-γ production were at the N terminus (amino acids 85 to 102 and 217 to 234). Its vaccine potential, along with protective immune responses in vivo, may be informative for vaccine development, particularly in regions where the M. tuberculosis Beijing/K-strain is frequently isolated from TB patients.

scholarly journals Differentiation of Antigen-Specific T Cells with Limited Functional Capacity during Mycobacterium tuberculosis Infection

2013 ◽  
Vol 82 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Yun Hee Jeong ◽  
Bo-Young Jeon ◽  
Sun-Hwa Gu ◽  
Sang-Nae Cho ◽  
Sung Jae Shin ◽  
...  
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Memory T Cells ◽  
Interleukin 2 ◽  
Effector Memory ◽  
Memory Cells ◽  
Content Type ◽  
Tnf Α ◽  
Ifn Γ

ABSTRACTDespite the generation ofMycobacterium tuberculosis-specific T cell immune responses during the course of infection, only 5 to 10% of exposed individuals develop active disease, while others develop a latent infection. This phenomenon suggests defectiveM. tuberculosis-specific immunity, which necessitates more careful characterization ofM. tuberculosis-specific T cell responses. Here, we longitudinally analyzed the phenotypes and functions ofM. tuberculosis-specific T cells. In contrast to the functional exhaustion of T cells observed after chronic infection,M. tuberculosis-specific CD8+T cells differentiated into either effector (CD127loCD62Llo) or effector memory (CD127hiCD62Llo) cells, but not central memory cells (CD127hiCD62Lhi), with low programmed death 1 (PD-1) expression, even in the presence of high levels of bacteria. Additionally,M. tuberculosis-specific CD8+and CD4+T cells produced substantial levels of tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ), but not interleukin 2 (IL-2), uponin vitrorestimulation. AmongM. tuberculosis-specific CD8+T cells, CD127hieffector memory cells displayed slower ongoing turnover but greater survival potential. In addition, these cells produced more IFN-γ and TNF-α and displayed lytic activity upon antigen stimulation. However, the effector function ofM. tuberculosis-specific CD8+CD127hieffector memory T cells was inferior to that of canonical CD8+CD127himemory T cells generated after acute lymphocytic choriomeningitis virus infection. Collectively, our data demonstrate thatM. tuberculosis-specific T cells can differentiate into memory T cells during the course ofM. tuberculosisinfection independent of the bacterial burden but with limited functionality. These results provide a framework for further understanding the mechanisms ofM. tuberculosisinfection that can be used to develop more effective vaccines.

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 Quest for Correlates of Protection against Tuberculosis

2015 ◽  
Vol 22 (3) ◽  
pp. 258-266 ◽  
Author(s):  
Kamlesh Bhatt ◽  
Sheetal Verma ◽  
Jerrold J. Ellner ◽  
Padmini Salgame
Keyword(s):  
T Cells ◽  
Vaccine Development ◽  
Interleukin 2 ◽  
T Cell Response ◽  
Content Type ◽  
Alternative Pathways ◽  
Correlates Of Protection ◽  
Human Immune Response ◽  
Ifn Γ ◽  
High Level

ABSTRACTA major impediment to tuberculosis (TB) vaccine development is the lack of reliable correlates of immune protection or biomarkers that would predict vaccine efficacy. Gamma interferon (IFN-γ) produced by CD4+T cells and, recently, multifunctional CD4+T cells secreting IFN-γ, tumor necrosis factor (TNF), and interleukin-2 (IL-2) have been used in vaccine studies as a measurable immune parameter, reflecting activity of a vaccine and potentially predicting protection. However, accumulating experimental evidence suggests that host resistance againstMycobacterium tuberculosisinfection is independent of IFN-γ and TNF secretion from CD4+T cells. Furthermore, the booster vaccine MVA85A, despite generating a high level of multifunctional CD4+T cell response in the host, failed to confer enhanced protection in vaccinated subjects. These findings suggest the need for identifying reliable correlates of protection to determine the efficacy of TB vaccine candidates. This article focuses on alternative pathways that mediateM. tuberculosiscontrol and their potential for serving as markers of protection. The review also discusses the significance of investigating the natural human immune response toM. tuberculosisto identify the correlates of protection in vaccination.

scholarly journals Protein Energy Malnutrition during Vaccination Has Limited Influence on Vaccine Efficacy but Abolishes Immunity if Administered during Mycobacterium tuberculosis Infection

2015 ◽  
Vol 83 (5) ◽  
pp. 2118-2126 ◽  
Author(s):  
Truc Hoang ◽  
Else Marie Agger ◽  
Joseph P. Cassidy ◽  
Jan P. Christensen ◽  
Peter Andersen
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Cd4 T Cells ◽  
Protein Energy Malnutrition ◽  
T Cell Subsets ◽  
Content Type ◽  
Protein Energy ◽  
Tnf Α ◽  
Ifn Γ

Protein energy malnutrition (PEM) increases susceptibility to infectious diseases, including tuberculosis (TB), but it is not clear how PEM influences vaccine-promoted immunity to TB. We demonstrate that PEM during low-level steady-state TB infection in a mouse model results in rapid relapse ofMycobacterium tuberculosis, as well as increased pathology, in bothMycobacterium bovisBCG-vaccinated and unvaccinated animals. PEM did not change the overall numbers of CD4 T cells in BCG-vaccinated animals but resulted in an almost complete loss of antigen-specific cytokine production. Furthermore, there was a change in cytokine expression characterized by a gradual loss of multifunctional antigen-specific CD4 T cells and an increased proportion of effector cells expressing gamma interferon and tumor necrosis factor alpha (IFN-γ+TNF-α+and IFN-γ+cells). PEM duringM. tuberculosisinfection completely blocked the protection afforded by the H56-CAF01 subunit vaccine, and this was associated with a very substantial loss of the interleukin-2-positive memory CD4 T cells promoted by this vaccine. Similarly, PEM during the vaccination phase markedly reduced the H56-CAF01 vaccine response, influencing all cytokine-producing CD4 T cell subsets, with the exception of CD4 T cells positive for TNF-α only. Importantly, this impairment was reversible and resupplementation of protein during infection rescued both the vaccine-promoted T cell response and the protective effect of the vaccine againstM. tuberculosisinfection.

scholarly journals Listeria-Vectored Vaccine Expressing the Mycobacterium tuberculosis 30-Kilodalton Major Secretory Protein via the Constitutively Active prfA* Regulon Boosts Mycobacterium bovis BCG Efficacy against Tuberculosis

2017 ◽  
Vol 85 (9) ◽  
Author(s):  
Qingmei Jia ◽  
Barbara Jane Dillon ◽  
Saša Masleša-Galić ◽  
Marcus A. Horwitz
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
Mycobacterium Bovis ◽  
Interleukin 2 ◽  
Secretory Protein ◽  
Broth Culture ◽  
Listeriolysin O ◽  
Content Type ◽  
Ifn Γ ◽  
Constitutively Active

ABSTRACT A potent vaccine against tuberculosis, one of the world's deadliest diseases, is needed to enhance the immunity of people worldwide, most of whom have been vaccinated with the partially effective Mycobacterium bovis BCG vaccine. Here we investigate novel live attenuated recombinant Listeria monocytogenes (rLm) vaccines expressing the Mycobacterium tuberculosis 30-kDa major secretory protein (r30/antigen 85B [Ag85B]) (rLm30) as heterologous booster vaccines in animals primed with BCG. Using three attenuated L. monocytogenes vectors, L. monocytogenes ΔactA (LmI), L. monocytogenes ΔactA ΔinlB (LmII), and L. monocytogenes ΔactA ΔinlB prfA* (LmIII), we constructed five rLm30 vaccine candidates expressing r30 linked in frame to the L. monocytogenes listeriolysin O signal sequence and driven by the hly promoter (h30) or linked in frame to the ActA N-terminal 100 amino acids and driven by the actA promoter (a30). All five rLm30 vaccines secreted r30 in broth and macrophages; while rLm30 expressing r30 via a constitutively active prfA* regulon (rLmIII/a30) expressed the largest amount of r30 in broth culture, all five rLm30 vaccines expressed equivalent amounts of r30 in infected macrophages. In comparative studies, boosting of BCG-immunized mice with rLmIII/a30 induced the strongest antigen-specific T-cell responses, including splenic and lung polyfunctional CD4+ T cells expressing the three cytokines interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin-2 (IL-2) (P < 0.001) and splenic and lung CD8+ T cells expressing IFN-γ (P < 0.0001). In mice and guinea pigs, the rLmIII/a30 and rLmI/h30 vaccines were generally more potent booster vaccines than r30 with an adjuvant and a recombinant adenovirus vaccine expressing r30. In a setting in which BCG alone was highly immunoprotective, boosting of mice with rLmIII/a30, the most potent of the vaccines, significantly enhanced protection against aerosolized M. tuberculosis (P < 0.01).

scholarly journals Functionally Overlapping Variants Control Tuberculosis Susceptibility in Collaborative Cross Mice

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Clare M. Smith ◽  
Megan K. Proulx ◽  
Rocky Lai ◽  
Michael C. Kiritsy ◽  
Timothy A. Bell ◽  
...  
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Collaborative Cross ◽  
Content Type ◽  
Trait Loci ◽  
Ifn Γ ◽  
Bacterial Control

ABSTRACT Host genetics plays an important role in determining the outcome of Mycobacterium tuberculosis infection. We previously found that Collaborative Cross (CC) mouse strains differ in their susceptibility to M. tuberculosis and that the CC042/GeniUnc (CC042) strain suffered from a rapidly progressive disease and failed to produce the protective cytokine gamma interferon (IFN-γ) in the lung. Here, we used parallel genetic and immunological approaches to investigate the basis of CC042 mouse susceptibility. Using a population derived from a CC001/Unc (CC001) × CC042 intercross, we mapped four quantitative trait loci (QTL) underlying tuberculosis immunophenotypes (Tip1 to Tip4). These included QTL that were associated with bacterial burden, IFN-γ production following infection, and an IFN-γ-independent mechanism of bacterial control. Further immunological characterization revealed that CC042 animals recruited relatively few antigen-specific T cells to the lung and that these T cells failed to express the integrin alpha L (αL; i.e., CD11a), which contributes to T cell activation and migration. These defects could be explained by a CC042 private variant in the Itgal gene, which encodes CD11a and is found within the Tip2 interval. This 15-bp deletion leads to aberrant mRNA splicing and is predicted to result in a truncated protein product. The ItgalCC042 genotype was associated with all measured disease traits, indicating that this variant is a major determinant of susceptibility in CC042 mice. The combined effect of functionally distinct Tip variants likely explains the profound susceptibility of CC042 mice and highlights the multigenic nature of tuberculosis control in the Collaborative Cross. IMPORTANCE The variable outcome of Mycobacterium tuberculosis infection observed in natural populations is difficult to model in genetically homogeneous small-animal models. The newly developed Collaborative Cross (CC) represents a reproducible panel of genetically diverse mice that display a broad range of phenotypic responses to infection. We explored the genetic basis of this variation, focusing on a CC line that is highly susceptible to M. tuberculosis infection. This study identified multiple quantitative trait loci associated with bacterial control and cytokine production, including one that is caused by a novel loss-of-function mutation in the Itgal gene, which is necessary for T cell recruitment to the infected lung. These studies verify the multigenic control of mycobacterial disease in the CC panel, identify genetic loci controlling diverse aspects of pathogenesis, and highlight the utility of the CC resource.

scholarly journals Mapping of Murine Th1 Helper T-Cell Epitopes of Mycolyl Transferases Ag85A, Ag85B, and Ag85C from Mycobacterium tuberculosis

2003 ◽  
Vol 71 (1) ◽  
pp. 483-493 ◽  
Author(s):  
S. D'Souza ◽  
V. Rosseels ◽  
M. Romano ◽  
A. Tanghe ◽  
O. Denis ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Interleukin 2 ◽  
T Cell Response ◽  
Mouse Strains ◽  
T Cell Epitopes ◽  
Dna Encoding ◽  
Amino Acid Region ◽  
Ifn Γ ◽  
Carboxy Terminal

ABSTRACT BALB/c (H-2d ) and C57BL/6 (H-2b ) mice were infected intravenously with Mycobacterium tuberculosis H37Rv or vaccinated intramuscularly with plasmid DNA encoding each of the three mycolyl transferases Ag85A, Ag85B, and Ag85C from M. tuberculosis. Th1-type spleen cell cytokine secretion of interleukin-2 (IL-2) and gamma interferon (IFN-γ) was analyzed in response to purified Ag85 components and synthetic overlapping peptides covering the three mature sequences. Tuberculosis-infected C57BL/6 mice reacted strongly to some peptides from Ag85A and Ag85B but not from Ag85C, whereas tuberculosis-infected BALB/c mice reacted only to peptides from Ag85A. In contrast, spleen cells from both mouse strains produced elevated levels of IL-2 and IFN-γ following vaccination with Ag85A, Ag85B, and Ag85C DNA in response to peptides of the three Ag85 proteins, and the epitope repertoire was broader than in infected mice. Despite pronounced sequence homology, a number of immunodominant regions contained component specific epitopes. Thus, BALB/c mice vaccinated with all three Ag85 genes reacted against the same amino acid region, 101 to 120, that was also immunodominant for Ag85A in M. bovis BCG-vaccinated and tuberculosis-infected H-2d haplotype mice, but responses were completely component specific. In C57BL/6 mice, a cross-reactive T-cell response was detected against two carboxy-terminal peptides spanning amino acids 241 to 260 and 261 to 280 of Ag85A and Ag85B. These regions were not recognized at all in C57BL/6 mice vaccinated with Ag85C DNA. Our results underline the need for comparative analysis of all three Ag85 components in future vaccination studies.

scholarly journals Synthetic Long Peptide Derived from Mycobacterium tuberculosis Latency Antigen Rv1733c Protects against Tuberculosis

2015 ◽  
Vol 22 (9) ◽  
pp. 1060-1069 ◽  
Author(s):  
Mariateresa Coppola ◽  
Susan J. F. van den Eeden ◽  
Louis Wilson ◽  
Kees L. M. C. Franken ◽  
Tom H. M. Ottenhoff ◽  
...  
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
Protective Efficacy ◽  
Bacterial Load ◽  
Effective Vaccine ◽  
Protective Capacity ◽  
Content Type ◽  
Ifn Γ ◽  
Vaccine Approach

ABSTRACTResponsible for 9 million new cases of active disease and nearly 2 million deaths each year, tuberculosis (TB) remains a global health threat of overwhelming dimensions.Mycobacterium bovisBCG, the only licensed vaccine available, fails to confer lifelong protection and to prevent reactivation of latent infection. Although 15 new vaccine candidates are now in clinical trials, an effective vaccine against TB remains elusive, and new strategies for vaccination are vital. BCG vaccination fails to induce immunity againstMycobacterium tuberculosislatency antigens. Synthetic long peptides (SLPs) combined with adjuvants have been studied mostly for therapeutic cancer vaccines, yet not for TB, and proved to induce efficient antitumor immunity. This study investigated an SLP derived from Rv1733c, a majorM. tuberculosislatency antigen which is highly expressed by “dormant”M. tuberculosisand well recognized by T cells from latentlyM. tuberculosis-infected individuals. In order to assess itsin vivoimmunogenicity and protective capacity, Rv1733c SLP in CpG was administered to HLA-DR3 transgenic mice. Immunization with Rv1733c SLP elicited gamma interferon-positive/tumor necrosis factor-positive (IFN-γ+/TNF+) and IFN-γ+CD4+T cells and Rv1733c-specific antibodies and led to a significant reduction in the bacterial load in the lungs ofM. tuberculosis-challenged mice. This was observed both in a pre- and in a post-M. tuberculosischallenge setting. Moreover, Rv1733c SLP immunization significantly boosted the protective efficacy of BCG, demonstrating the potential ofM. tuberculosislatency antigens to improve BCG efficacy. These data suggest a promising role forM. tuberculosislatency antigen Rv1733c-derived SLPs as a novel TB vaccine approach, both in a prophylactic and in a postinfection setting.

scholarly journals Clinical Significance of Interleukin-2/Gamma Interferon Ratios in Mycobacterium tuberculosis-Specific T-Cell Signatures

2011 ◽  
Vol 18 (8) ◽  
pp. 1395-1396 ◽  
Author(s):  
Franziska Suter-Riniker ◽  
Antonia Berger ◽  
Désirée Mayor ◽  
Pascal Bittel ◽  
Patricia Iseli ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Simultaneous Determination ◽  
Clinical Significance ◽  
Interleukin 2 ◽  
Gamma Interferon ◽  
Content Type ◽  
Ifn Γ

ABSTRACTThe simultaneous determination of interleukin-2 (IL-2) and gamma interferon (IFN-γ) in QuantiFERON-TB test plasma supernatants permitted the detection of shifts inMycobacterium tuberculosis-specific T-cell signatures. A subset of the 84 subjects tested revealed a significantly elevated IL-2/IFN-γ ratio, which may be a marker for the successful elimination ofM. tuberculosisinfection.

scholarly journals DNA Sequences Encoding CD4+ and CD8+T-Cell Epitopes Are Important for Efficient Protective Immunity Induced by DNA Vaccination with a Trypanosoma cruziGene

2001 ◽  
Vol 69 (9) ◽  
pp. 5477-5486 ◽  
Author(s):  
Adriana E. Fujimura ◽  
Sheila S. Kinoshita ◽  
Vera L. Pereira-Chioccola ◽  
Mauricio M. Rodrigues
Keyword(s):  
T Cells ◽  
T Cell ◽  
Dna Sequences ◽  
Protective Immunity ◽  
Catalytic Domain ◽  
Protective Efficacy ◽  
Cell Epitope ◽  
T Cell Epitopes ◽  
Ifn Γ ◽  
Domain Iii

ABSTRACT Immunization of BALB/c mice with a plasmid containing the gene forTrypanosoma cruzi trans-sialidase (TS) induced antibodies that inhibited TS enzymatic activity, CD4+ Th1 and CD8+ Tc1 cells, and protective immunity against infection. We used this model to obtain basic information on the requirement of CD4 or CD8 or B-cell epitopes for an effective DNA-induced immunity against T. cruzi infection. For that purpose, mice were immunized with plasmids containing DNA sequences encoding (i) the entire TS protein, (ii) the TS enzymatic domain, (iii) the TS CD4+ T-cell epitopes, (iv) the TS CD8+T-cell epitope, or (v) TS CD4+ and CD8+T-cell epitopes. Plasmids expressing the entire TS or its enzymatic domain elicited similar levels of TS-inhibitory antibodies, γ interferon (IFN-γ)-producing T cells, and protective immunity against infection. Although the plasmid expressing TS CD4 epitopes was immunogenic, its protective efficacy against experimental infection was limited. The plasmid expressing the CD8 epitope was poorly immunogenic and provided little protective immunity. The reason for the limited priming of CD8+ T cells was due to a requirement for CD4+ T cells. To circumvent this problem, a plasmid expressing both CD4+ and CD8+ T-cell epitopes was produced. This plasmid generated levels of IFN-γ-producing T cells and protective immunity comparable to that of the plasmid expressing the entire catalytic domain of TS. Our observations suggest that plasmids expressing epitopes recognized by CD4+ and CD8+ T cells may have a better protective potential against infection with T. cruzi.

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