Alpha-v-containing integrins are host receptors for the Plasmodium falciparum sporozoite surface protein, TRAP.

Malaria-causing Plasmodium sporozoites are deposited in the dermis by the bite of an infected mosquito and move by gliding motility to the liver where they invade and develop within host hepatocytes. Although extracellular interactions between Plasmodium sporozoite ligands and host receptors provide important guidance cues for productive infection and are good vaccine targets, these interactions remain largely uncharacterized. Thrombospondin-related anonymous protein (TRAP) is a parasite cell surface ligand that is essential for both gliding motility and invasion because it couples the extracellular binding of host receptors to the parasite cytoplasmic actinomyosin motor; however, the molecular nature of the host TRAP receptors is poorly defined. Here, we use a systematic extracellular protein interaction screening approach to identify the integrin αvβ3 as a directly interacting host receptor for Plasmodium falciparum TRAP. Biochemical characterization of the interaction suggests a two-site binding model, requiring contributions from both the von Willebrand factor A domain and the RGD motif of TRAP for integrin binding. We show that TRAP binding to cells is promoted in the presence of integrin-activating proadhesive Mn2+ ions, and that cells genetically targeted so that they lack cell surface expression of the integrin αv-subunit are no longer able to bind TRAP. P. falciparum sporozoites moved with greater speed in the dermis of Itgb3-deficient mice, suggesting that the interaction has a role in sporozoite migration. The identification of the integrin αvβ3 as the host receptor for TRAP provides an important demonstration of a sporozoite surface ligand that directly interacts with host receptors. Copyright © 2018 the Author(s). Published by PNAS

Synergistic malaria vaccine combinations identified by systematic antigen screening.

A highly effective vaccine would be a valuable weapon in the drive toward malaria elimination. No such vaccine currently exists, and only a handful of the hundreds of potential candidates in the parasite genome have been evaluated. In this study, we systematically evaluated 29 antigens likely to be involved in erythrocyte invasion, an essential developmental stage during which the malaria parasite is vulnerable to antibody-mediated inhibition. Testing antigens alone and in combination identified several strain-transcending targets that had synergistic combinatorial effects in vitro, while studies in an endemic population revealed that combinations of the same antigens were associated with protection from febrile malaria. Video microscopy established that the most effective combinations targeted multiple discrete stages of invasion, suggesting a mechanistic explanation for synergy. Overall, this study both identifies specific antigen combinations for high-priority clinical testing and establishes a generalizable approach that is more likely to produce effective vaccines

RECHERCHE DE MUTATIONS DANS LE GENE JAGGED1, RESPONSABLE DU SYNDROME D'ALAGILLE ET ETUDE DE SON PROFIL D'EXPRESSION AU COURS DE L'EMBRYOGENESE HUMAINE NORMALE

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Performance evaluation of Hyperledger Fabric-enabled framework for pervasive peer-to-peer energy trading in smart Cyber–Physical Systems

The in-depth collaboration of Cyber–Physical Systems (CPSs) and smart grids constitute the novel paradigm of distributed energy trading, in which computation and process control are managed in an adaptive Peer-to-Peer (P2P) manner. To further strengthen this collaboration, Hyperledger Fabric (HF) can be prominently considered as a mean to implement next-generation secure and intelligent communication. However, implementing real-world applications on this platform may concern performance issues. For the constructive exploration of these issues, initially, we design a novel P2P energy trading framework for improving resource utilization and consequently addressing the impending electricity crisis challenge. Thenceforward, we evaluate the results based on the different system operational parameters for establishing a proof-of-concept. For determining performance bottlenecks and best-configuration, these results are investigated independently by using the Nectar Research Cloud, thereby sustaining scalability. The proposed evaluation approach will largely contribute to determining the system operational-level parameters of enterprise applications that will utilize the HF platform as their communication tool-support. In addition, a benchmark is presented based on the Hyperledger Caliper tool to facilitate application designers and developers in the form of selecting an appropriate implementation model across the two latest stable HF model versions. The illustrative CPS-enabled energy trading scenario corroborates the feasibility of the proposed framework to foster the development of HF-assisted smart P2P energy trading mechanisms

MTRAP and Semaphorin-7A interact via their TSR and Sema domains.

<p>(<b>A</b>) Expression of individual domains of MTRAP and Semaphorin-7A. Schematics of the MTRAP ligand and Semaphorin-7A receptor as they would appear in the membrane are shown on the left with individual domains labelled plus a signal peptide (black box). The entire ectodomain and subfragments containing the individual domains of MTRAP (left blot) and Semaphorin-7A (right blot) were resolved by SDS-PAGE under reducing conditions and detected by Western blot using Streptavidin-HRP. Predicted molecular weights (kDa) are indicated in brackets; MTRAP has an additional processed band at around 30 kDa corresponding to the size of the Cd4d3+4-tag (TAG = Cd4d3+4-Biotin). (<b>B</b>) The two MTRAP TSR domains presented in tandem but not individually, bind Semaphorin-7A using the AVEXIS assay. Biotinylated entire ectodomains and individual domains of MTRAP (left graph) and Semaphorin-7A (right graph) were used as baits in the AVEXIS assay against Semaphorin-7A and MTRAP preys, respectively. The different Semaphorin-7A domains show no binding using this technique. Bar graphs represent mean ± SEM, n = 3. (<b>C</b>) MTRAP TSR 1+2 bind Semaphorin-7A with similar kinetics as the entire ectodomain of MTRAP. Serial dilutions of purified Semaphorin-7A were injected over biotinylated TSR1+2 immobilised on a streptavidin-coated sensor chip until equilibrium was reached (upper inset). Reference-subtracted binding data were plotted as a binding curve and an equilibrium dissociation constant calculated as before. A <i>K</i>_D of 1.96±0.03 µM (mean ± SEM) was calculated from three independent experiments (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003031#ppat.1003031.s004" target="_blank">Table S1</a>). A representative experiment is shown. No binding was observed with TSR1 or TSR2 individually (lower inset). (<b>D</b>) The Sema domain binds MTRAP with similar kinetics as the entire ectodomain of Semaphorin-7a. Serial dilutions of purified MTRAP were injected over the biotinylated Semaphorin-7A ectodomain or each individual domains (Sema, PSI and Ig-like) immobilised on a streptavidin-coated sensor chip. Binding was observed with the Sema domain (top graph) with a <i>K</i>_D of 0.83±0.43 (mean ± SEM), calculated from two independent experiments. No binding was observed with the PSI or Ig domains individually (bottom graph).</p

Semaphorin-7A is an erythrocyte receptor for MTRAP.

<p>(<b>A</b>) Schematic diagram showing how TRAP-like ligands are thought to play a key bridging role between the parasite and the target cell that is to be invaded. In this case, the cytoplasmic region of MTRAP interacts with the parasite actin-myosin motor that provides the power necessary for invasion. The extracellular region of MTRAP interacts with an erythrocyte receptor thereby providing the necessary traction for forwards movement of the parasite, driving host cell invasion. (<b>B</b>) Purified monomeric and pentameric MTRAP bound human erythrocytes relative to a negative control (pentameric Cd200). Unbound, wash and eluted material was resolved under reducing conditions by SDS-PAGE and detected by Western blotting using an anti-His antibody. Predicted monomer molecular weights are indicated in brackets. The pentamers are expected to split into the constituent monomers upon reduction. (<b>C</b>) Systematic screening identifies Semaphorin-7A as an MTRAP receptor. MTRAP was screened against an erythrocyte receptor protein library using the AVEXIS assay, either as a prey against 40 erythrocyte baits (top panel) or as a bait against 36 erythrocyte preys (bottom panel). A single interaction with Semaphorin-7A (protein number 23) was identified in both bait–prey orientations. Bar graphs represent means ± SD, n = 3. (<b>D</b>) MTRAP and Semaphorin-7A directly interact. Serial dilutions of purified monomeric Semaphorin-7A were injected over MTRAP immobilised on a streptavidin-coated sensor chip until equilibrium had been achieved (inset). Reference-subtracted binding data were plotted as a binding curve and the equilibrium dissociation constant was calculated using non-linear regression fitting of a simple Langmuir binding isotherm to the data. A <i>K</i>_D of 1.18±0.40 µM (mean ± SEM) was calculated from three independent experiments (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003031#ppat.1003031.s004" target="_blank">Table S1</a>). A representative experiment is shown.</p