HIV envelope V3 region mimic embodies key features of a broadly neutralizing antibody lineage epitope

HIV-1 envelope (Env) mimetics are candidate components of prophylactic vaccines and potential therapeutics. Here we use a synthetic V3-glycopeptide (“Man9-V3”) for structural studies of an HIV Env third variable loop (V3)-glycan directed, broadly neutralizing antibody (bnAb) lineage (“DH270”), to visualize the epitope on Env and to study how affinity maturation of the lineage proceeded. Unlike many previous V3 mimetics, Man9-V3 encompasses two key features of the V3 region recognized by V3-glycan bnAbs—the conserved GDIR motif and the N332 glycan. In our structure of an antibody fragment of a lineage member, DH270.6, in complex with the V3 glycopeptide, the conformation of the antibody-bound glycopeptide conforms closely to that of the corresponding segment in an intact HIV-1 Env trimer. An additional structure identifies roles for two critical mutations in the development of breadth. The results suggest a strategy for use of a V3 glycopeptide as a vaccine immunogen

Staged induction of HIV-1 glycan–dependent broadly neutralizing antibodies

A preventive HIV-1 vaccine should induce HIV-1–specific broadly neutralizing antibodies (bnAbs). However, bnAbs generally require high levels of somatic hypermutation (SHM) to acquire breadth, and current vaccine strategies have not been successful in inducing bnAbs. Because bnAbs directed against a glycosylated site adjacent to the third variable loop (V3) of the HIV-1 envelope protein require limited SHM, the V3-glycan epitope is an attractive vaccine target. By studying the cooperation among multiple V3-glycan B cell lineages and their coevolution with autologous virus throughout 5 years of infection, we identify key events in the ontogeny of a V3-glycan bnAb. Two autologous neutralizing antibody lineages selected for virus escape mutations and consequently allowed initiation and affinity maturation of a V3-glycan bnAb lineage. The nucleotide substitution required to initiate the bnAb lineage occurred at a low-probability site for activation-induced cytidine deaminase activity. Cooperation of B cell lineages and an improbable mutation critical for bnAb activity defined the necessary events leading to breadth in this V3-glycan bnAb lineage. These findings may, in part, explain why initiation of V3-glycan bnAbs is rare, and suggest an immunization strategy for inducing similar V3-glycan bnAbs

Mimicry of an HIV broadly neutralizing antibody epitope with a synthetic glycopeptide.

CAPRISA, 2017.Abstract available in pdf

Nouveaux vecteurs pseudo-peptidiques de structure linéaire, branchée ou dendrimérique (étude du transport d'une cargaison peptidique dans les cellules de mammifères)

L OBJECTIF DE CE TRAVAIL A ÉTÉ LE DÉVELOPPEMENT DE NOUVEAUX VECTEURS PSEUDO-PEPTIDIQUES, DE STRUCTURE VARIABLE, STABLES EN MILIEU BIOLOGIQUE, CAPABLES DE TRANSPORTER PLUS EFFICACEMENT UNE CARGAISON PEPTIDIQUE DANS DES CELLULES CHO. Afin de pouvoir accéder à des transporteurs de structure variée, la bis-ornithine, un nouvel acide aminé C , -disubstitué a été synthétisé. Ce composé est la pièce maîtresse d unités monomériques, dont l agencement modulable permet d accéder à des structures hétérofonctionnalisées : linéaires, branchées ou dendrimériques. Neuf nouveaux transporteurs ont ainsi été synthétisés sur support solide. Leur aptitude à transporter une espèce peptidique (le PKCi : inhibiteur des protéines kinases C) dans des cellules CHO a été évaluée, grâce à une nouvelle méthode de quantification, utilisant la spectrométrie de masse MALDI-TOF. Certains de ces composés sont jusqu'à 10 fois plus efficaces que les peptides vecteurs les plus utilisés. Une étude, par microscopie confocale, de la localisation intracellulaire de la cargaison, a permis de souligner une distribution, fonction de la nature du transporteur utilisé.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Répertoire des rituels et processionnaux imprimés conservés en France

, . Répertoire des rituels et processionnaux imprimés conservés en France. Aubervilliers : Institut de Recherche et d'Histoire des Textes (IRHT), 1984. 720 p. (Documents, études et répertoires de l'Institut de Recherche et d'Histoire des Textes, 32

Dosage et pistage de peptides Troyens dans les cellules

Les peptides Troyens ou vecteurs sont capables de passer les membranes biologiques et de véhiculer des principes actifs dans le cytoplasme ou le noyau des cellules dans lesquelles ils sont entrés. Les méthodes indirectes utilisées jusqu'à présent pour détecter ces peptides dans les cellules n'ont pas permis d'établir de manière univoque le(s) mécanisme(s) de leur internalisation. La méthode de quantification, basée sur la spectrométrie de masse MALDI-TOF, que nous avons mise au point pour quantifier ces peptides Troyens dans les cellules est développée dans cette revue

Cooperation between somatic mutation and germline-encoded residues enables antibody recognition of HIV-1 envelope glycans.

Viral glycoproteins are a primary target for host antibody responses. However, glycans on viral glycoproteins can hinder antibody recognition since they are self glycans derived from the host biosynthesis pathway. During natural HIV-1 infection, neutralizing antibodies are made against glycans on HIV-1 envelope glycoprotein (Env). However, such antibodies are rarely elicited with vaccination. Previously, the vaccine-induced, macaque antibody DH501 was isolated and shown to bind to high mannose glycans on HIV-1 Env. Understanding how DH501 underwent affinity maturation to recognize glycans could inform vaccine induction of HIV-1 glycan antibodies. Here, we show that DH501 Env glycan reactivity is mediated by both germline-encoded residues that contact glycans, and somatic mutations that increase antibody paratope flexibility. Only somatic mutations in the heavy chain were required for glycan reactivity. The paratope conformation was fragile as single mutations within the immunoglobulin fold or complementarity determining regions were sufficient for eliminating antibody function. Taken together, the initial germline VHDJH rearrangement generated contact residues capable of binding glycans, and somatic mutations were required to form a flexible paratope with a cavity conducive to HIV-1 envelope glycan binding. The requirement for the presence of most somatic mutations across the heavy chain variable region provides one explanation for the difficulty in inducing anti-Env glycan antibodies with HIV-1 Env vaccination

Star nanoparticles delivering HIV-1 peptide minimal immunogens elicit near-native envelope antibody responses in nonhuman primates.

Peptide immunogens provide an approach to focus antibody responses to specific neutralizing sites on the HIV envelope protein (Env) trimer or on other pathogens. However, the physical characteristics of peptide immunogens can limit their pharmacokinetic and immunological properties. Here, we have designed synthetic "star" nanoparticles based on biocompatible N-[(2-hydroxypropyl)methacrylamide] (HPMA)-based polymer arms extending from a poly(amidoamine) (PAMAM) dendrimer core. In mice, these star nanoparticles trafficked to lymph nodes (LNs) by 4 hours following vaccination, where they were taken up by subcapsular macrophages and then resident dendritic cells (DCs). Immunogenicity optimization studies revealed a correlation of immunogen density with antibody titers. Furthermore, the co-delivery of Env variable loop 3 (V3) and T-helper peptides induced titers that were 2 logs higher than if the peptides were given in separate nanoparticles. Finally, we performed a nonhuman primate (NHP) study using a V3 glycopeptide minimal immunogen that was structurally optimized to be recognized by Env V3/glycan broadly neutralizing antibodies (bnAbs). When administered with a potent Toll-like receptor (TLR) 7/8 agonist adjuvant, these nanoparticles elicited high antibody binding titers to the V3 site. Similar to human V3/glycan bnAbs, certain monoclonal antibodies (mAbs) elicited by this vaccine were glycan dependent or targeted the GDIR peptide motif. To improve affinity to native Env trimer affinity, nonhuman primates (NHPs) were boosted with various SOSIP Env proteins; however, significant neutralization was not observed. Taken together, this study provides a new vaccine platform for administration of glycopeptide immunogens for focusing immune responses to specific bnAb epitopes