Immunogenicity of Self-Associated Aggregates and Chemically Cross-Linked Conjugates of the 42 kDa Plasmodium falciparum Merozoite Surface Protein-1

Self-associated protein aggregates or cross-linked protein conjugates are, in general, more immunogenic than oligomeric or monomeric forms. In particular, the immunogenicity in mice of a recombinant malaria transmission blocking vaccine candidate, the ookinete specific Plasmodium falciparum 25 kDa protein (Pfs25), was increased more than 1000-fold when evaluated as a chemical cross-linked protein-protein conjugate as compared to a formulated monomer. Whether alternative approaches using protein complexes improve the immunogenicity of other recombinant malaria vaccine candidates is worth assessing. In this work, the immunogenicity of the recombinant 42 kDa processed form of the P. falciparum merozoite surface protein 1 (MSP142) was evaluated as a self-associated, non-covalent aggregate and as a chemical cross-linked protein-protein conjugate to ExoProtein A, which is a recombinant detoxified form of Pseudomonas aeruginosa exotoxin A. MSP142 conjugates were prepared and characterized biochemically and biophysically to determine their molar mass in solution and stoichiometry, when relevant. The immunogenicity of the MSP142 self-associated aggregates, cross-linked chemical conjugates and monomers were compared in BALB/c mice after adsorption to aluminum hydroxide adjuvant, and in one instance in association with the TLR9 agonist CPG7909 with an aluminum hydroxide formulation. Antibody titers were assessed by ELISA. Unlike observations made for Pfs25, no significant enhancement in MSP142 specific antibody titers was observed for any conjugate as compared to the formulated monomer or dimer, except for the addition of the TLR9 agonist CPG7909. Clearly, enhancing the immunogenicity of a recombinant protein vaccine candidate by the formation of protein complexes must be established on an empirical basis

Microstructured Surfaces Cause Severe but Non-Detrimental Deformation of the Cell Nucleus

Surface features on the length scale of organelles allow their manipulation. Here, we present observations of an unexpected deformation of nuclei within cells growing on surfaces with micrometer-sized pillars. Our results demonstrate that a microstructured surface can induce strong shape deformations in cells, without harmful consequences, and strongly suggest that these are limited to cancerous cells

Uninhibited chickens: ranging behaviour impacts motor self-regulation in free-range broiler chickens (Gallus gallus domesticus)

International audienceInhibiting impulsive, less flexible behaviours is of utmost importance for individual adaptation in an ever-changing environment. However, problem-solving tasks may be greatly impacted by individual differences in behaviour, since animals with distinct behavioural types perceive and interact with their environment differently, resulting in variable responses to the same stimuli. Here, we tested whether and how differences in ranging behaviour of free-range chickens affect motor self-regulation performance during a cylinder task. For this task, subjects must refrain from trying to reach a food reward through the walls of a transparent cylinder and detour to its open sides, as a sign of inhibition. Free-range chickens exhibited an overall low performance in the motor self-regulation task (31.33 +/- 13.55% of correct responses), however, high rangers showed significantly poorer performance than the low rangers (23.75 +/- 9.16% versus 40 +/- 12.90%, respectively). These results give further support to the impacts of individual behavioural differences on cognitive performances. This is the first demonstration to our knowledge of a relationship between exploratory tendencies and motor self-regulation for an avian species

Cognition in the barn: range use and its relation to cognitive performance in free-range broiler chickens (Gallus gallus domesticus)

International audienceFree-range chickens are not all the same. Within the same group, under the same conditions, some individuals explore the range more than others. In many animal species, including chickens, individuals differ in behavior and cognition, i.e., how they perceive, process, and memorize information from their environment. We aimed to further understand the relationship between range use, spatial and non-spatial memory, and inhibitory control in two groups of free-range broiler chickens: those who frequently explore the range (‘high rangers, HR’) and those who prefer to stay in or near the barn (‘low rangers, LR’). Experiments were conducted on two flocks of broiler chickens (n=200 per flock) reared in similar conditions. To test spatial and non-spatial memory, an arena with 8 cups was used. During the training phase, individuals (nLR = 20, nHR = 21) learned that only a white cup among seven black cups was baited. To find the target cup, individuals could rely either on their spatial memory (the position of the cup in relation to the cues on the arena’s walls), or rely on their non-spatial memory (the color of the cup). Two probe tests, on two different days, for spatial memory (all cups are black) and non-spatial memory (the white cup changed its previous position) revealed that LR were quicker to visit the target cup during the spatial memory compared to HR (LR: 60.47 ± 44.58 s, HR: 80.60 ± 47.15 s; ranging level: t = − 2.21, p = 0.03; observation day: t = 0.36, p = 0.71). No differences between groups were found for non-spatial memory (Day 1: U = 195, p = 0.70, Day 2: U = 199, p = 0.77). To test inhibitory control, individuals (nLR = 7, nHR = 8) learned to detour either side of an opaque cylinder to gain a food reward. In the test condition, chickens were presented with a transparent cylinder in ten trials. As a sign of inhibition, subjects needed to refrain from trying to reach the food reward through the walls of the cylinder and detour to its open sides. LR were significantly more successful than HR (LR: 40 ± 12.90%, HR: 23.75 ± 9.16%, p = 0.028). Overall, our results show that LR chickens perform better in cognitive tasks compared to HR chickens. These results contribute to the growing body of research into the behavior and cognition of free-range chickens. This knowledge is essential for, ultimately, applying husbandry procedures that increase range use for all animals

Oligonucleotide nanostructured surfaces : effect on escherichia coli curli expression

Oligonucleotide model surfaces allowing independent variation of topography and chemical composition were designed to study the adhesion and biofilm growth of E.coli. Surfaces were produced by covalent binding of oligonucleotides and immobilization of nucleotide-based vesicles. Their properties were confirmed through a combination of fluorescence microscopy, XPS, ellipsometry, AFM and wettability Studies at each step of the process. These sur-faces were then used to study the response of three different strains of E.coli quantified in a static biofilm growth mode. This study led to convincing evidence that oligonucleotide-modified surfaces, independent of the topographical feature used in this study, enhanced curli expression without an increase in the number of adherent bacteria

A Method for Producing Protein Nanoparticles with Applications in Vaccines.

A practical method is described for synthesizing conjugated protein nanoparticles using thioether (thiol-maleimide) cross-linking chemistry. This method fills the need for a reliable and reproducible synthesis of protein conjugate vaccines for preclinical studies, which can be adapted to produce comparable material for clinical studies. The described method appears to be generally applicable to the production of nanoparticles from a variety of soluble proteins having different structural features. Examples presented include single-component particles of the malarial antigens AMA1, CSP and Pfs25, and two component particles comprised of those antigens covalently cross-linked with the immunogenic carrier protein EPA (a detoxified form of exotoxin A from Pseudomonas aeruginosa). The average molar masses (Mw) of particles in the different preparations ranged from 487 kDa to 3,420 kDa, with hydrodynamic radii (Rh) ranging from 12.1 nm to 38.3 nm. The antigenic properties and secondary structures of the proteins within the particles appear to be largely intact, with no significant changes seen in their far UV circular dichroism spectra, or in their ability to bind conformation-dependent monoclonal antibodies. Mice vaccinated with mixed particles of Pfs25 or CSP and EPA generated significantly greater antigen-specific antibody levels compared with mice vaccinated with the respective unmodified monomeric antigens, validating the potential of antigen-EPA nanoparticles as vaccines