Estudio conformacional de péptidos modificados de las proteínas STARP, CelTOS, TRSP y SERA 5 de Plasmodium falciparum y su relación con una respuesta inmune en malaria

El desarrollo de una vacuna contra malaria es un área de exploración activa pero con enormes retos debido especialmente a la complejidad del ciclo del parásito. Así, es necesario bloquear las diferentes etapas de la invasión que tiene el Plasmodium falciparum y extraer de ellas la mayor información posible de la artillería que utiliza para su ataque. Para esto, péptidos de las proteínas STARP, CelTOS y TRSP (del esporozoito) y SERA 5 (del merozoito) que tienen alta afinidad de unión a células HepG2 y a glóbulos rojos respectivamente (conocidos como cHABPs), han sido modificados (conocidos como mHABPs), sintetizados y evaluados a nivel de respuesta inmune en monos Aotus así como estudiados en su conformación estructural por RMN de 1H. Los resultados muestran que los péptidos nativos no son inmunogénicos, pero pueden inducir altos títulos de anticuerpos cuando sus residuos críticos o sus vecinos son reemplazados por otro con un volumen y masa similar, pero diferente polaridad. El estudio conformacional pone de manifiesto que las estructuras de los péptidos nativos son diferentes de sus péptidos modificados ya sea que muestren regiones estructuradas más cortas o más largas o que no presenten ninguna, en comparación con sus análogos modificados altamente inmunogénicos. Las características estereoquímicas particulares en las cadenas laterales de algunos residuos de aminoácidos de estos péptidos modificados así como los rasgos fisicoquímicos parecen jugar un rol importante en la respuesta inmune apropiada cuando estos fueron inmunizados en grupos de monos Aotus confiriendo un avance al diseño de una vacuna contra malaria totalmente eficaz.

Identification of two Th1 cell epitopes on the Babesia bovis-encoded 77-kilodalton merozoite protein (Bb-1) by use of truncated recombinant fusion proteins

Previous studies have demonstrated the serologic and T-cell immunogenicity for cattle of a recombinant form of the apical complex-associated 77-kDa merozite protein of Babesia bovis, designated Bb-1. The present study characterizes the immunogenic epitopes of the Bb-1 protein. A series of recombinant truncated fusion proteins spanning the majority of the Bb-1 protein were expressed in Escherichia coli, and their reactivities with bovine peripheral blood mononuclear cells and T-cell clones derived from B. bovis-immune cattle and with rabbit antibodies were determined. Lymphocytes from two immune cattle were preferentially stimulated by the N-terminal half of the Bb-1 protein (amino acids 23 to 266, termed Bb-1A), localizing the T-cell epitopes to the Bb-1A portion of the molecule. CD4+ T-cell clones derived by stimulation with the intact Bb-1 fusion protein were used to identify two T-cell epitopes in the Bb-1A protein, consisting of amino acids SVVLLSAFSGN VWANEAEVSQVVK and FSDVDKTKSTEKT (residues 23 to 46 and 82 to 94). In contrast, rabbit antiserum raised against the intact fusion protein reacted only with the C-terminal half of the protein (amino acids 267 to 499, termed Bb-1B), which contained 28 tandem repeats of the tetrapeptide PAEK or PAET. Biological assays and Northern (RNA) blot analyses for cytokines revealed that following activation with concanavalin A, T-cell clones reactive against the two Bb-1A epitopes produced interleukin-2, gamma interferon, and tumor necrosis factors beta and alpha, but not interleukin-4, suggesting that the Bb-1 antigen preferentially stimulates the Th1 subset of CD4+ T cells in cattle. The studies described here report for the first time the characterization, by cytokine production, of the Th1 subset of bovine T cells and show that, as in mice, protozoal antigens can induce Th1 cells in ruminants. This first demonstration of B. bovis-encoded Th1 cell epitopes provides a rationale for incorporation of all or part of the Bb-1 protein into a recombinant vaccine.

Evaluation of an enzyme immunoassay for hepatitis C virus antibody detection using a recombinant protein derived from the core region of hepatitis C virus genome

This study was undertaken to evaluate an enzyme immunoassay (EIA) for hepatitis C virus antibody detection (anti-HCV), using just one antigen. Anti-HCV EIA was designed to detect anti-HCV IgG using on the solid-phase a recombinant C22 antigen localized at the N-terminal end of the core region of HCV genome, produced by BioMérieux. The serum samples diluted in phosphate buffer saline were added to wells coated with the C22, and incubated. After washings, the wells were loaded with conjugated anti-IgG, and read in a microtiter plate reader (492 nm). Serum samples of 145 patients were divided in two groups: a control group of 39 patients with non-C hepatitis (10 acute hepatitis A, 10 acute hepatitis B, 9 chronic hepatitis B, and 10 autoimmune hepatitis) and a study group consisting of 106 patients with chronic HCV hepatitis. In the study group all patients had anti-HCV detected by a commercially available EIA (Abbott®), specific for HCV structural and nonstructural polypeptides, alanine aminotransferase elevation or positive serum HCV-RNA detected by nested-PCR. They also had a liver biopsy compatible with chronic hepatitis. The test was positive in 101 of the 106 (95%) sera from patients in the study group and negative in 38 of the 39 (97%) sera from those in the control group, showing an accuracy of 96%. According to these results, our EIA could be used to detect anti-HCV in the serum of patients infected with hepatitis C virus.

Myocardial angiogenesis induction with bone protein derived growth factors (animal experiment).

Myocardial angiogenesis induction with vascular growth factors constitutes a potential strategy for patients whose coronary artery disease is refractory to conventional treatment. The importance of angiogenesis in bone formation has led to the development of growth factors derived from bovine bone protein. Twelve pigs (mean weight, 73 +/- 3 kg) were chosen for the study. In the first group (n = 6, growth factor group) five 100 micrograms boluses of growth factors derived from bovine bone protein, diluted in Povidone 5%, were injected in the lateral wall of the left ventricle. In the second group (n = 6, control group), the same operation was performed but only the diluting agent was injected. All the animals were sacrificed after 28 days and the vascular density of the left lateral wall (expressed as the number of vascular structures per mm2) as well as the area of blood vessel profiles per myocardial area analysed were determined histologically with a computerised system. The growth factor group had a capillary density which was significantly higher than that of the control group: 12.6 +/- 0.9/mm2 vs 4.8 +/- 0.5/mm2 (p < 0.01). The same holds true for the arteriolar density: 1 +/- 0.2/mm2 vs 0.3 +/- 0.1/mm2 (p < 0.01). The surface ratios of blood vessel profiles per myocardial area were 4900 +/- 800 micron 2/mm2 and 1550 +/- 400 micron 2/mm2 (p < 0.01) respectively. In this experimental model, bovine bone protein derived growth factors induce a significant neovascularisation in healthy myocardium, and appear therefore as promising candidates for therapeutic angiogenesis.

Preclinical vaccine study of Plasmodium vivax circumsporozoite protein derived-synthetic polypeptides formulated in montanide ISA 720 and montanide ISA 51 adjuvants.

Plasmodium vivax circumsporozoite (CS) protein is a leading malaria vaccine candidate previously assessed in animals and humans. Here, combinations of three synthetic polypeptides corresponding to amino (N), central repeat (R), and carboxyl (C) regions of the CS protein formulated in Montanide ISA 720 or Montanide ISA 51 adjuvants were assessed for immunogenicity in rodents and primates. BALB/c mice and Aotus monkeys were divided into test and control groups and were immunized three times with doses of 50 and 100 μg of vaccine or placebo. Antigen-specific antimalarial antibodies were determined by enzyme-linked immunosorbent assay, immunofluorescent antibody test, and IFN-γ responses by enzyme-linked immunosorbent spot (ELIspot). Both vaccine formulations were highly immunogenic in both species. Mice developed better antibody responses against C and R polypeptides, whereas the N polypeptide was more immunogenic in monkeys. Anti-peptide antibodies remained detectable for several months and recognized native proteins on sporozoites. Differences between Montanide ISA 720 and Montanide ISA 51 formulations were not significant.

Thermomechanical relaxation and different water states in cottonseed protein derived bioplastics

Thermomechanical relaxation events and different water states in cottonseed protein bioplastics are presented whilst investigating the effects of aldehyde cross-linking agents. Thermomechanical relaxation of cottonseed protein bioplastics associated with protein denaturation, moisture absorption and broad glass transitions (Tg) were observed from DSC and DMA measurements. It was shown that variation of the aldehyde influences the storage modulus at very low temperature (below Tg). From measurements of the water fusion point, enthalpy, vaporisation, and weight loss, three water states in the water-absorbed bioplastics are suggested; namely strongly-bound-to-polymer, weakly-bound-to-polymer and bulk-like water. The water content and unreacted cross-linking agents are influential factors in controlling formation of the different water states, whilst the selection of different aldehydes was found to be negligible. These results could be valuable for adjusting the thermomechanical relaxations of protein based bioplastics, and tailoring their properties in wet environments.

Production of the refolded oligopeptide-binding protein (OppA) encoded by the citrus pathogen Xanthomonas axonopodis pv. citri

The oligopeptide-binding protein, OppA, binds and ushers oligopeptide substrates to the membrane-associated oligopeptide permease (Opp), a multi-component ABC-type transporter involved in the uptake of oligopeptides expressed by several bacterial species. In the present study, we report the cloning, purification, refolding and conformational analysis of a recombinant OppA protein derived from Xanthomonas axonopodis pv. citri (X. citri), the etiological agent of citrus canker. The oppA gene was expressed in Escherichia coli BL21 (DE3) strain under optimized inducing conditions and the recombinant protein remained largely insoluble. Solubilization was achieved following refolding of the denatured protein. Circular dichroism analysis indicated that the recombinant OppA protein preserved conformational features of orthologs expressed by other bacterial species. The refolded recombinant OppA represents a useful tool for structural and functional analyses of the X. citri protein.

Plasmodium vivax recombinant vaccine candidate AMA-1 plays an important role in adaptive immune response eliciting differentiation of dendritic cells

The Apical Membrane Antigen-1 (AMA-1) is a well-characterized and functionally important merozoite protein and is currently considered a major candidate antigen for a malaria vaccine. Previously, we showed that AMA-1 has an influence on cellular immune responses of malaria-naive subjects, resulting in an alternative activation of monocyte-derived dendritic cells and induction of a pro-inflammatory response by stimulated PBMCs. Although there is evidence, from human and animal malaria model systems that cell-mediated immunity may contribute to both protection and pathogenesis, the knowledge on cellular immune responses in vivax malaria and the factors that may regulate this immunity are poorly understood. In the current work, we describe the maturation of monocyte-derived dendritic cells of P. vivax naturally infected individuals and the effect of P. vivax vaccine candidate Pv-AMA-1 on the immune responses of the same donors. We show that malaria-infected subjects present modulation of DC maturation, demonstrated by a significant decrease in expression of antigen-presenting molecules (CD1a, HLA-ABC and HLA-DR), accessory molecules (CD40, CD80 and CD86) and Fc gamma RI (CD64) receptor (P <= 0.05). Furthermore, Pv-AMA-1 elicits an upregulation of CD1a and HLA-DR molecules on the surface of monocyte-derived dendritic cells (P=0.0356 and P=0.0196, respectively), and it is presented by AMA-1-stimulated DCs. A significant pro-inflammatory response elicited by Pv-AMA-1-pulsed PBMCs is also demonstrated, as determined by significant production of TNF-alpha, IL-12p40 and IFN-gamma (P <= 0.05). Our results suggest that Pv-AMA-1 may partially revert DC down-modulation observed in infected subjects, and exert an important role in the initiation of pro-inflammatory immunity that might contribute substantially to protection. (c) 2009 Elsevier Ltd. All rights reserved.

The Mr 140,000 Intermediate Chain of Chlamydomonas Flagellar Inner Arm Dynein Is a WD-Repeat Protein Implicated in Dynein Arm Anchoring

Previous structural and biochemical studies have revealed that the inner arm dynein I1 is targeted and anchored to a unique site located proximal to the first radial spoke in each 96-nm axoneme repeat on flagellar doublet microtubules. To determine whether intermediate chains mediate the positioning and docking of dynein complexes, we cloned and characterized the 140-kDa intermediate chain (IC140) of the I1 complex. Sequence and secondary structural analysis, with particular emphasis on β-sheet organization, predicted that IC140 contains seven WD repeats. Reexamination of other members of the dynein intermediate chain family of WD proteins indicated that these polypeptides also bear seven WD/β-sheet repeats arranged in the same pattern along each intermediate chain protein. A polyclonal antibody was raised against a 53-kDa fusion protein derived from the C-terminal third of IC140. The antibody is highly specific for IC140 and does not bind to other dynein intermediate chains or proteins in Chlamydomonas flagella. Immunofluorescent microscopy of Chlamydomonas cells confirmed that IC140 is distributed along the length of both flagellar axonemes. In vitro reconstitution experiments demonstrated that the 53-kDa C-terminal fusion protein binds specifically to axonemes lacking the I1 complex. Chemical cross-linking indicated that IC140 is closely associated with a second intermediate chain in the I1 complex. These data suggest that IC140 contains domains responsible for the assembly and docking of the I1 complex to the doublet microtubule cargo.

Spontaneous human squamous cell carcinomas are killed by a human cytotoxic T lymphocyte clone recognizing a wild-type p53-derived peptide

A cytotoxic T lymphocyte (CTL) clone generated in vitro from the peripheral blood of a healthy HLA-A2-positive individual against a synthetic p53 protein-derived wild-type peptide (L9V) was shown to kill squamous carcinoma cell lines derived from two head and neck carcinomas, which expressed mutant p53 genes, in a L9V/HLA-A2 specific and restricted fashion. Thus, the normal tolerance against endogenously processed p53 protein-derived self-epitopes can be broken by peptide-specific in vitro priming. p53 protein-derived wild-type peptides might thus represent tumor associated target molecules for immunotherapeutical approaches.

Intermediate pyrolysis and product identification by TGA and Py-GC/MS of green microalgae and their extracted protein and lipid components

The thermo-chemical conversion of green microalgae Chlamydomonas reinhardtii wild type (CCAP 11/32C), its cell wall deficient mutant C. reinhardtii CW15 (CCAP 11/32CW15) and Chlorella vulgaris (CCAP 211/11B) as well as their proteins and lipids was studied under conditions of intermediate pyrolysis. The microalgae were characterised for ultimate and gross chemical composition, lipid composition and extracted products were analysed by Thermogravimetric analysis (TG/DTG) and Pyrolysis-gaschromatography/mass-spectrometry (Py-GC/MS). Proteins accounted for almost 50% and lipids 16-22 % of dry weight of cells with little difference in the lipid compositions between the C. reinhardtii wild type and the cell wall mutant. During TGA analysis, each biomass exhibited three stages of decomposition, namely dehydration, devolatilization and decomposition of carbonaceous solids. Py-GC/MS analysis revealed significant protein derived compounds from all algae including toluene, phenol, 4-methylphenol, 1H-indole, 1H-indole-3methyl. Lipid pyrolysis products derived from C. reinhardtii wild type and C. reinhardtii CW15 were almost identical and reflected the close similarity of the fatty acid profiles of both strains. Major products identified were phytol and phytol derivatives formed from the terpenoid chain of chlorophyll, benzoic acid alkyl ester derivative, benzenedicarboxylic acid alkyl ester derivative and squalene. In addition, octadecanoic acid octyl ester, hexadecanoic acid methyl ester and hydrocarbons including heptadecane, 1-nonadecene and heneicosane were detected from C. vulgaris pyrolysed lipids. These results contrast sharply with the types of pyrolytic products obtained from terrestrial lignocellulosic feedstocks and reveal that intermediate pyrolysis of algal biomass generates a range of useful products with wide ranging applications including bio fuels.

Vitellogenesis in Manduca sexta

Eggs of Manduca sexta contain four well-characterized protein derived from hemolymph: vitellogenin and lipophorin (very high density lipoproteins); microvitellogenin, a 26,000 dalton female-specific protein lacking lipid and carbohydrate, and insecticyanin, a blue biliprotein composed of four identical 22,000 dalton subunits. In addition, eggs contain a large store of triacyl glycerols. It has been shown that vitellogenin and lipophorin are actively taken up by follicles in vitro. The lipid components of these two proteins together account for only 10% of egg lipid. The follicle actively sequesters intact high density lipophorin, which, inside the oocyte, is stripped of much of its neutral lipid and two molecules of apolipophorin III. On the other hand, low density lipophorin donates diacylglycerol to the oocyte without its protein components being sequestered. Most of the egg lipid is transported from the fat body by a shuttle system involving low density lipophorin.

Substrate specificity of human kallikrein 2 (hK2) as determined by phage display technology.

Human glandular kallikrein 2 (hK2) is a trypsin-like serine protease expressed predominantly in the prostate epithelium. Recently, hK2 has proven to be a useful marker that can be used in combination with prostate specific antigen for screening and diagnosis of prostate cancer. The cleavage by hK2 of certain substrates in the proteolytic cascade suggest that the kallikrein may be involved in prostate cancer development; however, there has been very little other progress toward its biochemical characterization or elucidation of its true physiological role. In the present work, we adapt phage substrate technology to study the substrate specificity of hK2. A phage-displayed random pentapeptide library with exhaustive diversity was generated and then screened with purified hK2. Phages displaying peptides susceptible to hK2 cleavage were amplified in eight rounds of selection and genes encoding substrates were transferred from the phage to a fluorescent system using cyan fluorescent protein (derived from green fluorescent protein) that enables rapid determination of specificity constants. This study shows that hK2 has a strict preference for Arg in the P1 position, which is further enhanced by a Ser in P'1 position. The scissile bonds identified by phage display substrate selection correspond to those of the natural biological substrates of hK2, which include protein C inhibitor, semenogelins, and fibronectin. Moreover, three new putative hK2 protein substrates, shown elsewhere to be involved in the biology of the cancer, have been identified thus reinforcing the importance of hK2 in prostate cancer development.

Elicitation of specific cytotoxic T cells by immunization with malaria soluble synthetic polypeptides.

We have studied the immunogenicity of Plasmodium falciparum circumsporozoite (CS) protein-derived synthetic polypeptides in mice. These synthetic peptides correspond to the N- and the C-terminal domains 22-125 and 289-390, respectively of the P. falciparum 7G8 isolate CS protein expressed on the sporozoite surface. They comprise what is believed to be the mature protein, except for the central repetitive B cell domain. BALB/c (H-2d) mice were immunized s.c. with 50 micrograms soluble CS polypeptides emulsified in IFA. After a single immunization, CS-specific helper and cytotoxic T lymphocytes (CTLs) could be obtained. The resultant CTLs obtained by in vitro restimulation of primed lymph node (LN) cells recognized H-2Kd target cells in the presence of short synthetic peptides defined in the present study. These epitopes are contained within the N- and C-terminal regions of the CS protein, and correspond to sequences 39-47 and 333-342. In addition, these CTLs can specifically lyse H-2d target cells transfected with the CS gene. These results suggest that, by immunization of mice with large soluble CS synthetic polypeptides in IFA, it is possible to obtain MHC class I-restricted T cell responses specific for the CS protein. This approach might be advantageous in the formulation of efficient malaria subunit vaccines.

Revisión sistemática de la literatura para el manejo de dolor central en esclerosis múltiple

El dolor es un síntoma muy común en pacientes con Esclerosis Múltiple, pues del 42 al 65% de los enfermos lo presentan, y es calificado como el síntoma más severo entre el 8 y el 32%. Todos los síndromes dolorosos centrales se presentan por lesión o disfunción del sistema nervioso central, causando discapacidad severa y deterioro de la calidad de vida de los pacientes.