Desarrollo de vacunas para la enfermedad de Chagas (CRUZIVAX): preferencias de las partes interesadas y posibles impactos en la asistencia sanitaria

A vaccine for Chagas disease does not currently exist. This study aims to inform the development of two vaccines for the prevention and treatment of Trypanosoma cruzi infection, and guide their pre-clinical phase up to clinical phase I. The three main objectives are: 1) to explore patients’ and policy makers’ preferences on the candidate vaccines in Argentina and Spain; 2) to investigate health-related quality of life of patients affected by Chagas disease; and 3) to assess the potential health provider savings associated with the vaccines, in terms of resource use and health care costs. Discrete choice experiments will be employed to estimate and characterize the theoretical demand for the vaccines and investigate patients’ and policy makers’ preferences. Health-related quality of life will be assessed using the EQ-5D-3L questionnaire. Resources use and costs associated with Chagas disease will be investigated using information from the databases of the Hospital Clínic of Barcelona

rs1004819 Is the Main Disease-Associated IL23R Variant in German Crohn's Disease Patients: Combined Analysis of IL23R, CARD15, and OCTN1/2 Variants

The IL23R gene has been identified as a susceptibility gene for inflammatory bowel disease (IBD) in the North American population. The aim of our study was to test this association in a large German IBD cohort and to elucidate potential interactions with other IBD genes as well as phenotypic consequences of IL23R variants. Genomic DNA from 2670 Caucasian individuals including 833 patients with Crohn's disease (CD), 456 patients with ulcerative colitis (UC), and 1381 healthy unrelated controls was analyzed for 10 IL23R SNPs. Genotyping included the NOD2 variants p.Arg702Trp, p.Gly908Arg, and p.Leu1007fsX1008 and polymorphisms in SLC22A4/OCTN1 (1672 C-->T) and SLC22A5/OCTN2 (-207 G-->C). All IL23R gene variants analyzed displayed highly significant associations with CD. The strongest association was found for the SNP rs1004819 [P = 1.92x10(-11); OR 1.56; 95 % CI (1.37-1.78)]. 93.2% of the rs1004819 TT homozygous carriers as compared to 78% of CC wildtype carriers had ileal involvement [P = 0.004; OR 4.24; CI (1.46-12.34)]. The coding SNP rs11209026 (p.Arg381Gln) was protective for CD [P = 8.04x10(-8); OR 0.43; CI (0.31-0.59)]. Similar, but weaker associations were found in UC. There was no evidence for epistasis between the IL23R gene and the CD susceptibility genes CARD15 and SLC22A4/5. IL23R is an IBD susceptibility gene, but has no epistatic interaction with CARD15 and SLC22A4/5. rs1004819 is the major IL23R variant associated with CD in the German population, while the p.Arg381Gln IL23R variant is a protective marker for CD and UC

Trans-Sialidase Inhibition Assay Detects Trypanosoma cruzi Infection in Different Wild Mammal Species

The detection of Trypanosoma cruzi infection in mammals is crucial for understanding the eco-epidemiological role of the different species involved in parasite transmission cycles. Xenodiagnosis (XD) and hemoculture (HC) are routinely used to detect T. cruzi in wild mammals. Serological methods are much more limited because they require the use of specific antibodies to immunoglobulins of each mammalian species susceptible to T. cruzi. In this study we detected T. cruzi infection by trans-sialidase (TS) inhibition assay (TIA). TIA is based on the antibody neutralization of a recombinant TS that avoids the use of anti-immunoglobulins. TS activity is not detected in the co-endemic protozoan parasites Leishmania spp and T. rangeli. In the current study, serum samples from 158 individuals of nine wild mammalian species, previously tested by XD, were evaluated by TIA. They were collected from two endemic areas in northern Argentina. The overall TIA versus XD co-reactivity was 98.7% (156/158). All 18 samples from XD-positive mammals were TIA-positive (co-positivity, 100%) and conegativity was 98.5% (138/140). Two XD-negative samples from a marsupial (Didelphis albiventris) and an edentate (Dasypus novemcinctus) were detected by TIA. TIA could be used as a novel tool for serological detection of Trypanosoma cruzi in a wide variety of sylvatic reservoir hosts.Fil: Sartor, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Ceballos, Leonardo A.. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Ecologia, Genetica y Evolucion. Laboratorio de Eco - Epidemiología; ArgentinaFil: Orozco, Maria Marcela. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Ecologia, Genetica y Evolucion. Laboratorio de Eco - Epidemiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cardinal, Marta Victoria. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Ecologia, Genetica y Evolucion. Laboratorio de Eco - Epidemiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gurtler, Ricardo Esteban. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Ecologia, Genetica y Evolucion. Laboratorio de Eco - Epidemiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Leguizamón, S. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; Argentin

Diagnostic Peptide Discovery: Prioritization of Pathogen Diagnostic Markers Using Multiple Features

<div><p>The availability of complete pathogen genomes has renewed interest in the development of diagnostics for infectious diseases. Synthetic peptide microarrays provide a rapid, high-throughput platform for immunological testing of potential B-cell epitopes. However, their current capacity prevent the experimental screening of complete “peptidomes”. Therefore, computational approaches for prediction and/or prioritization of diagnostically relevant peptides are required. In this work we describe a computational method to assess a defined set of molecular properties for each potential diagnostic target in a reference genome. Properties such as sub-cellular localization or expression level were evaluated for the whole protein. At a higher resolution (short peptides), we assessed a set of local properties, such as repetitive motifs, disorder (structured vs natively unstructured regions), trans-membrane spans, genetic polymorphisms (conserved vs. divergent regions), predicted B-cell epitopes, and sequence similarity against human proteins and other potential cross-reacting species (e.g. other pathogens endemic in overlapping geographical locations). A scoring function based on these different features was developed, and used to rank all peptides from a large eukaryotic pathogen proteome. We applied this method to the identification of candidate diagnostic peptides in the protozoan <em>Trypanosoma cruzi</em>, the causative agent of Chagas disease. We measured the performance of the method by analyzing the enrichment of validated antigens in the high-scoring top of the ranking. Based on this measure, our integrative method outperformed alternative prioritizations based on individual properties (such as B-cell epitope predictors alone). Using this method we ranked 10 million 12-mer overlapping peptides derived from the complete <em>T. cruzi</em> proteome. Experimental screening of 190 high-scoring peptides allowed the identification of 37 novel epitopes with diagnostic potential, while none of the low scoring peptides showed significant reactivity. Many of the metrics employed are dependent on standard bioinformatic tools and data, so the method can be easily extended to other pathogen genomes.</p> </div

Visualization of peptide-score profiles generated by the method.

<p>A) the 60S ribosomal protein L19 (locus identifier TcCLB.509149.40), and B) a putative lectin (locus TcCLB.506239.30). These plots display peptide scores and features along protein sequences. Mapped features in these examples are those listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050748#pone-0050748-t001" target="_blank">Table 1:</a> antigenicity (Bepipred), protein disorder, internal repeats, signal peptide, signal peptide cleavage site, non-synonymous polymorphisms, high conservation vs human, high conservation vs <i>Leishmania spp</i>, low sequence complexity, glycosylated threonines, cysteines, and presence of domain absent in orthologous proteins (NC DOMAIN). Vertical boxes represent overlapped 12-residue peptides, and their height and level of green are proportional to the peptide score. They vary around their base protein scores (i.e. 4.7 and 5.5), which accounts for subcellular localization and expression.</p

Assessing enrichment of known antigens.

<p>The figure shows a number of enrichment plots obtained under different prioritization scenarios. In all plots: the x axis contains the prioritized proteome (top ranking proteins at the origin); the y axis displays the fraction of known validated antigens recovered in the top x proteins; the blue dashed line displays an hypothetical enrichment plot with an AUC = 0.5 (expected by chance), while the black solid line represents the actual enrichment obtained in each prioritization. From the top-left: comparison of different prioritization strategies (ordered by decreasing AUC values): 1) our composite method, 2–9) a number of prioritizations using a single criteria in each case: 2) Codon Usage bias (CAI), 3) Internal repeats, 4) Proteomic evidence of expression, 5) natively unstructured regions, 6) antigenicity (Bepipred), 7) surface localization (GPI), 8) O-Glycosylation, 9) antigenicity (EMBOSS antigenic). p-value, p-value (p-values based on a random permutation test, n = 10,000).</p

Summary of peptide reactivities.

<p>The table summarizes the results from the screening of pools of positive (Chagas), negative (healthy donors) and related (Leishmaniasis) sera. From left to right the columns show the results of cumulative additional criteria (boolean AND): 1) Assayed, 2) Assayed AND Positive for Chagas Disease sera, etc.</p>§<p>derived from 85 distinct proteins.</p>†<p>derived from 27 distinct proteins.</p>*<p>derived from 23 distinct proteins.</p

Estimation of sensitivity and specificity of several Trypanosoma cruzi antibody assays in blood donors in Argentina.

BackgroundThe absence of a gold standard test for Trypanosoma cruzi antibodies represents a problem not only for the evaluation of screening tests, but also for appropriate blood donor counseling. The aim of this study was to estimate the sensitivity and specificity of multiple blood donor screening tests for T. cruzi antibodies in Argentina.Study design and methodsFrom June 2006 to March 2007 a sample of 1455 blood donors was recruited from two blood banks in Chaco province, an area of Argentina with highly endemic T. cruzi infection. Samples were tested by three epimastigote lysate enzyme immunoassays (EIAs), one recombinant antigen EIA, two indirect hemagglutination assay (IHA) tests, a particle agglutination assay (PA), and a research trans-sialidase inhibition assay (TIA). Sensitivity and specificity were estimated using latent class analysis (LCA).ResultsLCA estimated the consensus prevalence of T. cruzi infection at 24.5%. Interassay correlation was higher among the four EIA tests and TIA compared to IHA tests. Assay sensitivities varied from 96 to 99.7 for different EIAs, 91% for TIA, 84% for PA, and 66 to 74% for IHA tests. Relative to the LCA, assay specificities were from 96% to almost 100%.ConclusionBased on the comparison of several tests in a large population from an endemic area for T. cruzi infection, our data showed an adequate sensitivity for EIA tests in contrast to PA and IHA assays. The latter tests should no longer be used for blood donor screening

Estimation of sensitivity and specificity of several Trypanosoma cruzi antibody assays in blood donors in Argentina.

BackgroundThe absence of a gold standard test for Trypanosoma cruzi antibodies represents a problem not only for the evaluation of screening tests, but also for appropriate blood donor counseling. The aim of this study was to estimate the sensitivity and specificity of multiple blood donor screening tests for T. cruzi antibodies in Argentina.Study design and methodsFrom June 2006 to March 2007 a sample of 1455 blood donors was recruited from two blood banks in Chaco province, an area of Argentina with highly endemic T. cruzi infection. Samples were tested by three epimastigote lysate enzyme immunoassays (EIAs), one recombinant antigen EIA, two indirect hemagglutination assay (IHA) tests, a particle agglutination assay (PA), and a research trans-sialidase inhibition assay (TIA). Sensitivity and specificity were estimated using latent class analysis (LCA).ResultsLCA estimated the consensus prevalence of T. cruzi infection at 24.5%. Interassay correlation was higher among the four EIA tests and TIA compared to IHA tests. Assay sensitivities varied from 96 to 99.7 for different EIAs, 91% for TIA, 84% for PA, and 66 to 74% for IHA tests. Relative to the LCA, assay specificities were from 96% to almost 100%.ConclusionBased on the comparison of several tests in a large population from an endemic area for T. cruzi infection, our data showed an adequate sensitivity for EIA tests in contrast to PA and IHA assays. The latter tests should no longer be used for blood donor screening