Multi-epitope Approach Research Articles

Protective Efficacy of the Epitope-Conjugated Antigen N-Tc52/TSkb20 in Mitigating Trypanosoma cruzi Infection through CD8+ T-Cells and IFNγ Responses.

Chagas disease, caused by the protozoan Trypanosoma cruzi, remains a major public health challenge affecting millions in Latin America and worldwide. Although significant progress has been made in vector control, no vaccine exists to prevent infection or mitigate disease pathogenesis. We developed a rationally designed chimeric protein vaccine, N-Tc52/TSkb20, incorporating immunodominant epitopes from two T. cruzi antigens, the amino-terminal portion of Tc52 and the TSkb20 epitope derived from trans-sialidase. The objectives of this study were to construct and characterize the antigen and evaluate its protective potential in an immunoprophylactic murine model of T. cruzi infection. The N-Tc52/TSkb20 protein was recombinantly expressed in E. coli and its identity was confirmed using mass spectrometry and Western blotting. Immunization with the chimeric protein significantly controlled parasitemia and reduced the heart, colon, and skeletal muscle parasite burdens compared to non-vaccinated mice. Protection was superior to vaccination with the individual parental antigen components. Mechanistically, the vaccine induced potent CD8+ T-cell and IFNγ responses against the incorporated epitopes and a protective IgG antibody profile. A relatively low IL-10 response favored early parasite control. These results validate the promising multi-epitope approach and support the continued development of this type of rational vaccine design strategy against Chagas disease.

Targeted vaccine development against Bilophila wadsworthia to curb colon diseases: A multiepitope approach based on reverse vaccinology and computational analysis

The presence of excessive hydrogen sulfide (H2S)-producing bacteria, particularly Bilophila wadsworthia in appendices, is linked to a weaker colonic mucus barrier, inflammatory bowel disease, and colorectal cancer. Thus, targeting this bacterium could reduce sulfide levels and address associated health concerns. Here, we utilized reverse vaccinology and immunoinformatics to design a chimeric vaccine against B. wadsworthia, focusing on membrane-bound and extracellular proteins. Subtractive proteome analysis identified 18 potential vaccine candidates (PVCs), from which six B-cell, eight CD8+ T cell, and six CD4+ T cell epitopes were predicted. Chosen epitopes were assessed for immunological properties and cross-reactivity with human and mouse proteomes. Subsequently, these epitopes were fused with appropriate linkers, PADRE epitope, TAT peptide, and Cholera Toxin B subunit adjuvant to form a robust multi-epitope vaccine (MEV). The MEV's tertiary structure was modelled and validated for reliable analysis. Molecular docking and dynamics simulations demonstrated stable binding of MEV with Toll-like receptor 4. The MEV showed favorable physicochemical characteristics, high expression potential in Escherichia coli, broad population coverage (∼98 %), and cross-protection against different B. wadsworthia strains. Immune simulation suggested induction of strong B and T cell responses, including primary, secondary, and tertiary immune responses. Further experimental studies are necessary to validate these findings.

De Novo Design of a β-Helix Tau Protein Scaffold: An Oligomer-Selective Vaccine Immunogen Candidate for Alzheimer's Disease.

Tau pathology is associated with many neurodegenerative disorders, including Alzheimer's disease (AD), where the spatio-temporal pattern of tau neurofibrillary tangles strongly correlates with disease progression, which motivates therapeutics selective for misfolded tau. Here, we introduce a new avidity-enhanced, multi-epitope approach for protein-misfolding immunogen design, which is predicted to mimic the conformational state of an exposed epitope in toxic tau oligomers. A predicted oligomer-selective tau epitope 343KLDFK347 was scaffolded by designing a β-helix structure that incorporated multiple instances of the 16-residue tau fragment 339VKSEKLDFKDRVQSKI354. Large-scale conformational ensemble analyses involving Jensen-Shannon Divergence and the embedding depth showed that the multi-epitope scaffolding approach, employed in designing the β-helix scaffold, was predicted to better discriminate toxic tau oligomers than other "monovalent" strategies utilizing a single instance of an epitope for vaccine immunogen design. Using Rosetta, 10,000 sequences were designed and screened for the linker portions of the β-helix scaffold, along with a C-terminal stabilizing α-helix that interacts with the linkers, to optimize the folded structure and stability of the scaffold. Structures were ranked by energy, and the lowest 1% (82 unique sequences) were verified using AlphaFold. Several selection criteria involving AlphaFold are implemented to obtain a lead-designed sequence. The structure was further predicted to have free energetic stability by using Hamiltonian replica exchange molecular dynamics (MD) simulations. The synthesized β-helix scaffold showed direct binding in surface plasmon resonance (SPR) experiments to several antibodies that were raised to the structured epitope using a designed cyclic peptide. Moreover, the strength of binding of these antibodies to in vitro tau oligomers correlated with the strength of binding to the β-helix construct, suggesting that the construct presents an oligomer-like conformation and may thus constitute an effective oligomer-selective immunogen.

Cancer-testis antigen expression is shared between epithelial ovarian cancer tumors

ObjectivesCancer-testis (CT) antigens have been proposed as potential targets for cancer immunotherapy. Our objective was to evaluate the expression of a panel of CT antigens in epithelial ovarian cancer (EOC) tumor specimens, and to determine if antigen sharing occurs between tumors. MethodsRNA was isolated from EOC tumor specimens, EOC cell lines and benign ovarian tissue specimens. Real time-PCR analysis was performed to determine the expression level of 20 CT antigens. ResultsA total of 62 EOC specimens, 8 ovarian cancer cell lines and 3 benign ovarian tissues were evaluated for CT antigen expression. The majority of the specimens were: high grade (62%), serous (68%) and advanced stage (74%). 58 (95%) of the EOC tumors analyzed expressed at least one of the CT antigens evaluated. The mean number of CT antigen expressed was 4.5 (0-17). The most frequently expressed CT antigen was MAGE A4 (65%). Antigen sharing analysis showed the following: 9 tumors shared only one antigen with 62% of the evaluated specimens, while 37 tumors shared 4 or more antigens with 82%. 5 tumors expressed over 10 CT antigens, which were shared with 90% of the tumor panel. ConclusionCT antigens are expressed in 95% of EOC tumor specimens. However, not a single antigen was universally expressed across all samples. The degree of antigen sharing between tumors increased with the total number of antigens expressed. These data suggest a multi-epitope approach for development of immunotherapy for ovarian cancer treatment.

Tumor heterogeneity as a rationale for a multi-epitope approach in an autologous renal cell cancer tumor vaccine.

PurposeAn autologous tumor vaccine already used successfully in the immune therapy of renal cell carcinoma was investigated in detail. The evaluation of potential tumor markers should allow for the assessment of potency according to pharmaceutical regulations.MethodsA panel of 36 tumor-associated antigens and cellular marker proteins was characterized in a total of 133 tumor cell lysates by methods such as ELISA, Western blots, and topological proteomics. The induction of tumor-associated antigen-specific antibodies was demonstrated by immunization in mice.ResultsTumor heterogeneity was demonstrated: none of the tumor-associated antigens investigated were detectable in each tumor lysate. In parallel, the coincidental presence of potential danger signals was shown for HSP-60 and HSP-70. The presence of both antigen and danger signal allowed a successful induction of an immune response in a murine model.ConclusionThe verified tumor heterogeneity indicates the need for a multi-epitope approach for the successful immunotherapy in renal cell carcinoma.

Rationales for a Multi-Epitope Approach in an Autologous Renal Cell Cancer Tumor Vaccine

Objective: We report about a study according to a detailed characterization of an autologous tumor vaccine already used successfully in the immune therapy of renal cell carcinoma (RCC). The original paper was published in Onco Targets Therapy in 2016. This short communication summarizes the contents of the respective publication as well as shows new results of additional investigations by FACS-analysis. Method: A total of 133 tumor cell lysates (TCL) were investigated by ELISA, Western blots, topological proteomics and FACS analysis. Results: A total of 36 tumor-associated antigens (TAA) and cellular marker proteins were considered for analysis, whereof none was detectable in each tumor lysate. Moreover, the coincidental presence of potential danger signals was shown for HSP 60 and 70. Conclusion: In conclusion the verified tumor heterogeneity indicates the need for a multi-epitope approach for the successful immunotherapy in renal cell carcinoma.

Recent Advances in Epitope Design for Immunotherapy of Cancer

Eradication of cancer cells is imperative for a successful treatment of tumours. In addition to the existent chemotherapy or radiation therapy, other novel immunotherapeutic strategies to fight tumours are currently under investigation. One of these is cancer vaccination, an approach aimed at inducing effective immune responses in the host against defined tumour antigens. Among several classes of cancer vaccines, the subunit vaccines based on the single and multi epitope-approach are worthy of note as they offer an exquisite specificity in targeting only tumour cells. In this review we will focus on the significant advances made in the development and use of epitope-based cancer vaccines, reporting a selection of important and recent patents on tumour antigen discovery and epitope design for immunotherapy of cancer.

A novel multi-epitopic immune network model hybridized with neural theory and fuzzy concept

The natural immune system provides an effective defense mechanism against foreign substances via complex interactions among various cells and molecules. Jerne introduced the immune network theory to model the relation between immune cells and molecules. The immune system like the neural system is able to learn from experience. In this paper, a multi-epitopic immune network model is proposed. The proposed model is hybridized with Learning Vector Quantization (LVQ) and fuzzy set theory to present a new supervised learning method. The new method is called Hybrid Fuzzy Neuro-Immune Network based on Multi-Epitope approach (HFNINME). To evaluate the performance of the proposed method several experiments on benchmark classification problems are carried out and the results are compared with two prominent immune-based classifiers as well as several versions of the LVQ algorithm. The results of the experiments reveal that the proposed method yields a parsimonious classifier that can classify data more accurately and more efficiently.

Expression and purification of the minor histocompatibility antigen, HA-1H generated in Escherichia coli

The minor histocompatibility antigen HA-1H is a potential immunotherapeutic molecule. It can be used as a target for graft versus leukaemia reactions to eliminate residual HA-1H expressing leukaemic cells in patients following haemopoietic stem cell transplantation, whereby HA-1H primed donor cells can be transferred into a patient via adoptive immunotherapy. However, thus far only synthetic peptides corresponding to a HLA-A∗0201 restricted HA-1H epitope have been used to generate HA-1H specific T cells. We are the first laboratory to clone, express and purify a region of HA-1H using an Escherichia coli expression system. The recombinant HA-1H protein was purified under denaturing conditions and the affinity purification tag removed using thrombin to remove non-specific amino acids. The 92 amino acid recombinant protein was characterised by mass spectrometry. Our rationale is that by using a recombinant HA-1H protein rather than peptide, HA-1H specific T cells may be generated from presentation of multiple HA-1H epitopes complexed in different HLA molecules. A multi-epitope approach may have wider applicability and maybe more effective at leukaemia control. The recombinant HA-1H protein may also be used as a research tool to identify novel CD4 + helper T cell and CD8 + cytotoxic T cell epitopes.

Multi-epitope schistosome vaccine candidates tested for protective immunogenicity in mice

The major challenge in the development of anti-schistosome vaccines is to use defined antigens to stimulate an appropriate immune response that leads to resistance. Several promising candidate vaccine antigens including the glycolytic enzyme triose-phosphate isomerase (SmTPI), a 28 kDa glutathione- S-transferase (Sm28), the myofibrilar protein paramyosin (Sm97), an integral membrane protein (Sm23) and calpain (Smcalpain) have been characterised and their primary sequences derived for Schistosoma mansoni. Furthermore, sequences are available for synthetic peptides mimicking epitopes on these molecules capable of inducing schistosome-specific T- and B-cell responses. These schistosome vaccine candidates have generally been tested with varying degrees of success as single components, with only one report of the use of a multivalent antigen or multi-epitope approach. We describe the assembly of multiple defined and different epitopes of S. mansoni into a variety of single covalent structures; these included a DNA vaccine encoding different epitopes in tandem, the polyprotein itself that is encoded by this DNA and branched synthetic peptide epitope-based polymers in which the individual epitopes are pendant from an inert backbone. Each of the vaccine constructs examined, with the exception of the DNA vaccine, generated antibodies that were capable of binding to a tandem sequence of the epitopes. Although these results were encouraging, none of the constructs protected animals from subsequent challenge infection, indicating that the immune responses elicited were inadequate or inappropriate for parasite killing in vivo.

The Multi-epitope Approach for Immunotherapy for Cancer: Identification of Several CTL Epitopes from Various Tumor-Associated Antigens Expressed on Solid Epithelial Tumors

ABSTRACT: One approach to development of specific cancer immunotherapy relies on the induction of cytotoxic T lymphocytes (CTL) specific for tumor-associated antigens (TAA). Induction of TAA-specific CTL could be used towards the eradication of established tumors, or to prevent their dissemination or recurrence after primary treatment. The present study identifies a set of CTL epitopes from TAA frequently found on solid epithelial tumors such as breast, lung and gastro-intestinal tumors. Specifically, HLA-A2.1 binding peptides from the MAGE2, MAGE3, HER-2/ neu and CEA antigens were tested for their capacity to elicit in vitro anti-tumor CTL using lymphocytes from normal volunteers and autologous dendritic cells as antigen-presenting cells. A total of 6 new epitopes (MAGE2[10 157], MAGE3[9 112], CEA[9 691], CEA[9 24], HER2[9 435] and HER2[9 5]) were identified which were capable of specifically recognizing tumor cell lines expressing HLA-A2.1 and the corresponding TAA. In one case (CEA[9 24]), induction of vigorous anti-tumor CTL responses required epitope engineering to increase HLA-A2.1 binding affinity. Finally, most of the newly identified epitopes (5 out of 6) were found to be highly crossreactive with other common HLA alleles of the A2 supertype (A2.2, A2.3, A2.6 and A6802), thus demonstrating their potential in providing broad and non-ethnically biased population coverage. The results are discussed in the context of the development of multi-epitope-based therapies with broad applicability for patients suffering from commonly found tumors.

Precursor frequency analysis of cytotoxic T lymphocytes to pre-erythrocytic antigens of Plasmodium falciparum in West Africa.

Some individuals living in malaria-endemic areas have CTL to Plasmodium falciparum liver stage Ags. We have quantified these CTL responses using limiting dilution analysis studies on the peripheral blood cells of naturally exposed Gambian donors. CTL precursor frequencies were determined to a wide range of epitopes derived from different liver stage Ags (liver stage protein 1, circumsporozoite protein, thrombospondin-related anonymous protein, and sporozoite threonine/asparagine-rich protein) restricted through common HLA alleles present in this population (HLA-A2.1, -A2.2, -B7, -B8, -B35, and B53). Precursor frequencies were between 17 and 98/million PBMC and correlated with the levels of specific lysis in parallel bulk cultures. The quantitative nature of limiting dilution assay analysis revealed varying degrees of immunodominance in the CTL responses to different epitopes within single proteins (thrombospondin related anonymous protein: tr42, tr43, tr26, tr29, and tr39; circumsporozoite protein: cp6, cp26, and cp29) and within individual donors. The temporal stability of some of these CTL responses was determined over a 4-yr period. This is the first quantitative study of CTL specific for any plasmodial species or nonviral pathogen in humans and provides a basis for a multiepitope approach to malaria vaccination.

The immune system as a neural network: A multi-epitope approach

The term "neural network" has been applied to arrays of simple activation units linked by weighted connections. If the connections are modified according to a defined learning algorithm, such networks can be trained to store and retrieve patterned information. Memories are distributed throughout the network, allowing the network to recall complete patterns from incomplete input (pattern completion). The major biological application of neural network theory to date has been in the neurosciences, but the immune system may represent an alternative organ system in which to search for neural network architecture. Previous applications of parallel distributed processing to idiotype network theory have focused upon the recognition of individual epitopes. We argue here that this approach may be too restrictive, underestimating the power of neural network architecture. We propose that the network stores and retrieves large, complex patterns consisting of multiple epitopes separated in time and space. Such a network would be capable of perceiving an entire bacterium, and of storing the time course of a viral infection. While recognition of solitary epitopes occurs at the cellular level in this model, recognition of structures larger than the width of an antibody binding site takes place at the organ level, via network architecture integration of, i.e. individual epitope responses. The Oudin-Cazenave enigma, the sharing of idiotypic determinants by antibodies directed against distinct regions of the same antigen, suggests that some network level of integration of the individual clonal responses to large antigens does occur. The role of cytokines in prior neural network models of the immune system is unclear. We speculate that cytokines may influence the temperature of the network, such that changes in the cytokine milieu serve to "anneal" the network, allowing it to achieve the optimum steady-state in the shortest period of time.