Impact of hepatitis B virus basic core promoter mutations on T cell response to an immunodominant HBx-derived epitope

The hepatitis B X (HBx) protein is a crucial component in HBV infection in vivo and has been implicated in HCC. In this study, we aimed to detect and characterize peripheral HBx-specific T cells in chronically infected patients at the inactive carrier state of the disease. HBx-specific IFN-gamma-secreting T cells were found in 36 of 52 patients (69%), and 78% (28/36) of responding patients had T cells targeting epitopes in the carboxy-terminal part of HBx. IL-10 secretion after the stimulation of T cells with HBx-derived peptides was weak or undetectable. IFN-gamma-secreting T cells recognized a previously unknown immunodominant CD4+ T cell epitope, HBx 126-140 (EIRLKVFVLGGCRHK), in 86% (24 of 28) of patients. This peptide bound several HLA-DR molecules (HLA-DRB1*0101, HLA-DRB1*0401, HLA-DRB1*1301, and HLA-DRB5*0101). Its coding sequence overlaps a domain of the HBV genome encompassing the basic core promoter (BCP) region. Taking into account the selection of viral core promoter mutants during HBV infection, we found that HBV variants with BCP mutations were present in patient sera. We further demonstrated that these viral mutant sequences activated T cells specific for the immunodominant epitope only weakly, if at all. This is the first study linking BCP mutations and HBx-specific T cell responses.CONCLUSION:Wild-type and variant peptides may represent potential tools for monitoring the HBV-specific T cell responses involved in sequence evolution during disease progression. Finally, the degenerate HLA-DR binding of this promiscuous, immunodominant peptide would make it a valuable component of vaccines for protecting large and ethnically diverse patient populations

Development of a hypoallergenic recombinant parvalbumin for first-in-man subcutaneous immunotherapy of fish allergy.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.The FAST (food allergy-specific immunotherapy) project aims at developing safe and effective subcutaneous immunotherapy for fish allergy, using recombinant hypoallergenic carp parvalbumin, Cyp c 1.Preclinical characterization and good manufacturing practice (GMP) production of mutant Cyp (mCyp) c 1.Escherichia coli-produced mCyp c 1 was purified using standard chromatographic techniques. Physicochemical properties were investigated by gel electrophoresis, size exclusion chromatography, circular dichroism spectroscopy, reverse-phase high-performance liquid chromatography and mass spectrometry. Allergenicity was assessed by ImmunoCAP inhibition and basophil histamine release assay, immunogenicity by immunization of laboratory animals and stimulation of patients' peripheral blood mononuclear cells (PBMCs). Reference molecules were purified wild-type Cyp c 1 (natural and/or recombinant). GMP-compliant alum-adsorbed mCyp c 1 was tested for acute toxicity in mice and rabbits and for repeated-dose toxicity in mice. Accelerated and real-time protocols were used to evaluate stability of mCyp c 1 as drug substance and drug product.Purified mCyp c 1 behaves as a folded and stable molecule. Using sera of 26 double-blind placebo-controlled food-challenge-proven fish-allergic patients, reduction in allergenic activity ranged from 10- to 5,000-fold (1,000-fold on average), but with retained immunogenicity (immunization in mice/rabbits) and potency to stimulate human PBMCs. Toxicity studies revealed no toxic effects and real-time stability studies on the Al(OH)3-adsorbed drug product demonstrated at least 20 months of stability.The GMP drug product developed for treatment of fish allergy has the characteristics targeted for in FAST: i.e. hypoallergenicity with retained immunogenicity. These results have warranted first-in-man immunotherapy studies to evaluate the safety of this innovative vaccine.info:eu-repo/grantAgreement/EC/FP7/20187

High Therapeutic Efficacy of a New Survivin LSP-Cancer Vaccine Containing CD4+ and CD8+ T-Cell Epitopes

The efficacy of an antitumoral vaccine relies both on the choice of the antigen targeted and on its design. The tumor antigen survivin is an attractive target to develop therapeutic cancer vaccines because of its restricted over-expression and vital functions in most human tumors. Accordingly, several clinical trials targeting survivin in various cancer indications have been conducted. Most of them relied on short peptide-based vaccines and showed promising, but limited clinical results. In this study, we investigated the immunogenicity and therapeutic efficacy of a new long synthetic peptide (LSP)-based cancer vaccine targeting the tumor antigen survivin (SVX). This SVX vaccine is composed of three long synthetic peptides containing several CD4+ and CD8+ T-cell epitopes, which bind to various HLA class II and class I molecules. Studies in healthy individuals showed CD4+ and CD8+ T-cell immunogenicity of SVX peptides in human, irrespective of the individual's HLA types. Importantly, high frequencies of spontaneous T-cell precursors specific to SVX peptides were also detected in the blood of various cancer patients, demonstrating the absence of tolerance against these peptides. We then demonstrated SVX vaccine's high therapeutic efficacy against four different established murine tumor models, associated with its capacity to generate both specific cytotoxic CD8+ and multifunctional Th1 CD4+ T-cell responses. When tumors were eradicated, generated memory T-cell responses protected against rechallenge allowing long-term protection against relapses. Treatment with SVX vaccine was also found to reshape the tumor microenvironment by increasing the tumor infiltration of both CD4+ and CD8+ T cells but not Treg cells therefore tipping the balance toward a highly efficient immune response. These results highlight that this LSP-based SVX vaccine appears as a promising cancer vaccine and warrants its further clinical development

Development of a Humanized HLA-A2.1/DP4 Transgenic Mouse Model and the Use of This Model to Map HLA-DP4-Restricted Epitopes of HBV Envelope Protein

A new homozygous humanized transgenic mouse strain, HLA-A2.1+/+HLA-DP4+/+ hCD4+/+mCD4−/−IAβ−/−β2m−/− (HLA-A2/DP4), was obtained by crossing the previously characterized HLA-A2+/+β2m−/− (A2) mouse and our previously created HLA-DP4+/+ hCD4+/+mCD4−/−IAβ−/− (DP4) mouse. We confirmed that the transgenes (HLA-A2, HLA-DP4, hCD4) inherited from the parental A2 and DP4 mice are functional in the HLA-A2/DP4 mice. After immunizing HLA-A2/DP4 mice with a hepatitis B DNA vaccine, hepatitis B virus-specific antibodies, HLA-A2-restricted and HLA-DP4-restricted responses were observed to be similar to those in naturally infected humans. Therefore, the present study demonstrated that HLA-A2/DP4 transgenic mice can faithfully mimic human cellular responses. Furthermore, we reported four new HLA-DP4-restricted epitopes derived from HBsAg that were identified in both vaccinated HLA-A2/DP4 mice and HLA-DP4-positive human individuals. The HLA-A2/DP4 mouse model is a promising preclinical animal model carrying alleles present to more than a quarter of the human population. This model should facilitate the identification of novel HLA-A2- and HLA-DP4-restricted epitopes and vaccine development as well as the characterization of HLA-DP4-restricted responses against infection in humans

Evaluation des protéines Midkine et Survivine surexprimées dans les cellules tumorales comme cibles de l'immunité cellulaire anti-tumorale

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocSudocFranceF

Identification et optimisation d'épitopes T CD4+ du virus de l'hépatite C. Application a la vaccination peptidique

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Ingénierie de l'allergène majeur du venin d'abeille et identification d'épitopes T d'allergènes (application à la désensibilisation)

L'allergie est une maladie en pleine progression contre laquelle le seul traitement curatif est l'immunothérapie spécifique active. Cependant, ce traitement n'est pas totalement efficace (allergie aux pollens et aux acariens) et il n'est pas dénué de risques (allergie aux hyménoptères). Récemment, de nouvelles stratégies de désensibilisation ont émergé. Elles sont basées sur l'utilisation de nouvelles molécules, que l'on appelle allergoïdes, afin de sécuriser, mais également d'augmenter l'efficacité de l'immunothérapie. La plupart de ces molécules comportent les épitopes T, responsables de l'efficacité du traitement, mais sont dépourvues de réactivité aux IgE, responsables des effets secondaires. Elles ont pour but de moduler la réponse du système immunitaire en orientant la réponse Th2 établie vers une réponse Th1. Afin de proposer de nouvelles molécules, nous avons tout d'abord mis au point, par mutagenèse dirigée, un allergoïde recombinant de l'allergène majeur de venin d'abeille, la phospholipase A2 (Api m1). Ces mutations ont été introduites à la surface de la protéine, en dehors des zones épitopes T chez l'homme et chez la souris Balb/c. Ce mutant présente une faible réactivité vis-à-vis d'IgE et d'IgG de patients allergiques au venin d'abeille. En revanche, il conserve sa capacité à induire une prolifération des cellules T murines spécifiques de l'allergène natif. De manière intéressante, cet allergoïde conserve la structure secondaire de l'allergène natif alors qu'il possède une structure tertiaire flexible, différente de celle de la forme native. Cette propriété pourrait jouer un rôle important dans la perte d'allergénicité de cet allergoïde. Compte tenu de l'ensemble de ces propriétés, cette molécule constitue un candidat intéressant pour l'immunothérapie spécifique de l'allergie au venin d'abeille. Par ailleurs, de nouvelles méthodes d'identification d'épitopes T ont été mises au point. Ainsi, des déterminants de liaison ont été identifiés d'une part pour Api m 1 sur les molécules HLA-DP4, et d'autre part, pour un extrait allergénique brut (venin de guêpe) vis-à-vis des molécules HLA-DR. Enfin, au cours de diverses collaborations, l'identification d'épitopes T d'allergènes (Bos d 2, Fel d 1) et d'un antigène (le facteur VIII de la coagulation) a été réalisée. L'ensemble de ces résultats permet alors la conception d'allergoïdes sous forme synthétique (peptides contenant les épitopes T) ou recombinante (protéine mutée en dehors des zones épitopes T)PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Big in Japan: HLA-DRB1∗08:03 and immune thrombotic thrombocytopenic purpura

International audienc