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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Genetic and serologic characterization of a Swedish human hantavirus isolate

Lindkvist, Marie January 2008 (has links)
Hantaviruses are found practically all over the world and cause hemorrhagic fevers in man. Each year about 150,000 people are hospitalized in these zoonotic infections which can be of two types: hemorrhagic fever with renal syndrome (HFRS) or hantavirus cardiopulmonary syndrome (HCPS), depending on the infecting virus. Hantavirus infections are emerging infectious diseases. That is, the number of reported cases of hantaviral disease is increasing, new hantaviruses are discovered continually, and already known hantaviruses are expected to spread to new areas. Therefore, knowledge and monitoring of these viruses are imperative from a public health perspective. In this thesis, the characterization of a local human Puumala (PUUV) virus isolate is described. Genetic and serological relationships to other hantaviruses are investigated and the viral protein interactions, critical for genome packaging and assembly, are studied. We found that the nucleotide and amino acid sequences of the local PUUV strains are significantly different from the PUUV prototype strain Sotkamo, a difference that indicates that there might be a risk of misdiagnosing PUUV infected patients when using reagents derived from the prototype strain. These data contributed to the introduction of locally derived diagnostic tools to the Laboratory of Clinical Virology at the Umeå University hospital, which is the reference centre for hantaviral diseases in Sweden. Furthermore, when studying the underlying mechanisms of genome packaging, we identified several regions and amino acids absolutely required for nucleocapsid protein interactions. Also, a region that appeared to regulate this interaction was discovered. Finally, the serological immune responses in DNA-vaccinated mice and PUUV infected patients were investigated. We found that the cross-reactive antibody response in vaccinated mice and in infected individuals was unique and independent of homologous titres. Furthermore, four immunodominant epitopes with specific cross-reactive characteristics were identified. Our findings have highlighted the complexity of the serological immune responses to hantavirus infections, and they emphasize the importance of customizing the diagnostic tools and performing clinical analyses on locally derived strains. In conclusion, we believe that these results are valuable in the development of new serological, genetic, and epidemiological tools.
12

Novel Bioinformatics Applications for Protein Allergology, Genome-Wide Association and Retrovirology Studies

Martínez Barrio, Álvaro January 2010 (has links)
Recently, the pace of growth in the amount of data sources within Life Sciences has increased exponentially until pose a difficult problem to efficiently manage their integration. The data avalanche we are experiencing may be significant for a turning point in science, with a change of orientation from proprietary to publicly available data and a concomitant acceptance of studies based on the latter. To investigate these issues, a Network of Excellence (EMBRACE) was launched with the aim to integrate the major databases and the most popular bioinformatics software tools. The focus of this thesis is therefore to approach the problem of seamlessly integrating varied data sources and/or distributed research tools. In paper I, we have developed a web service to facilitate allergenicity risk assessment, based on allergen descriptors, in order to characterize proteins with the potential for sensitization and cross-reactivity. In paper II, a web service was developed which uses a lightweight protocol to integrate human endogenous retrovirus (ERV) data within a public genome browser. This new data catalogue and many other publicly available sources were integrated and tested in a bioinformatics-rich client application. In paper III, GeneFinder, a distributed tool for genome-wide association studies, was developed and tested. Useful information based on a particular genomic region can be easily retrieved and assessed. Finally, in paper IV, we developed a prototype pipeline to mine the dog genome for endogenous retroviruses and displaying the transcriptional landscape of these retroviral integrations. Moreover, we further characterized a group that until this point was believed to be primate-specific. Our results also revealed that the dog has been very effective in protecting itself from such integrations. This work integrates different applications in the fields of protein allergology, biotechnology, genome association studies and endogenous retroviruses. / EMBRACE NoE EU FP6
13

Produção de fragmentos de anticorpos monoclonais (scFv) contra isolados de campo do vírus da bronquite infecciosa das galinhas utilizando phage display

Fernandes, Camila Cesário [UNESP] 22 December 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-22Bitstream added on 2014-06-13T18:56:05Z : No. of bitstreams: 1 fernandes_cc_me_jabo.pdf: 1349174 bytes, checksum: b0d752648346a29041d0fbd5f330fbf6 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Anticorpos monoclonais se constituem na base de vários testes usados na detecção e na identificação de antígenos. Nesse contexto, tais imuno-reagentes têm sido extensivamente empregados na identificação de estirpes virais envolvidas na etiologia de surtos de bronquite infecciosa a campo, permitindo o aperfeiçoamento das técnicas de detecção e caracterização antigênica do vírus da bronquite infecciosa das galinhas (VBI). No presente estudo, uma biblioteca de fragmentos de anticorpos de galinha originalmente preparada por “phage display” contra a estirpe vacinal (H120) do VBI, foi usada para a seleção de fragmentos de anticorpos recombinantes com reatividade cruzada para as estirpes heterólogas IBVPR01, IBVPR05, isoladas de surtos a campo no Brasil e SE-17, isolada nos Estados Unidos. Após três ciclos de “panning”, foi identificado pelo ELISA um conjunto de 15 anticorpos scFv expressos em fagos e com reatividade cruzada para essas mesmas estirpes do VBI. A análise por Western-blotting revelou que três desses clones apresentavam fagos expressando fragmentos de anticorpos monoclonais com reatividade cruzada para a nucleoproteína N das três estirpes do VBI e também para a forma recombinante dessa nucleoproteína derivada da estirpe M41. Concluindo, os fragmentos de anticorpos monoclonais recombinantes scFv-N produzido em fagos interagem com um epítopo mais conservado da proteína N do VBI e apresentam um grande potencial para utilização na detecção e no diagnóstico direto desse vírus e no estudo de evolução de variantes desse vírus. / Monoclonal antibodies are the basis of various techniques used for antigen detection or characterization, and their use is specially recommended for the identification of viral strains involved in the etiology of outbreaks of infectious bronchitis, because these antibodies are homogeneous, highly specific and fully characterized, allowing the improvement of detection of immunological techniques and antigenic characterization of avian infectious bronchitis virus strains (IBV). We used a phage display library prepared previously against the IBV vaccine strain (H120) for the selection of new scFv antibody fragments reacting with heterologous IBV strains isolated from outbreaks in Brazil (IBVPR01, IBVPR05) and USA (SE-17). After three cycles of panning a set of 15 scFv antibodies was expressed in phages and exhibited crossreaction in ELISA with these three viral strains. Western-blotting analysis showed that three of this clone set were expressing scFv specific for the nucleoprotein of these IBV strains, as well as to the recombinant form of this protein derived from M41 strain of IBV. In conclusion, the recombinant fragments of monoclonal antibodies expressed by phage-display technique have a great potential for future use in immunodiagnostic techniques and study the evolution of variant strains of this virus.
14

Anticorpos anti-trypanosoma cruzi como preditivos de infec??o por leishmania infantum

Oliveira Filho, Jethe Nunes de 01 February 2013 (has links)
Made available in DSpace on 2014-12-17T14:03:40Z (GMT). No. of bitstreams: 1 JetheNOF_DISSERT.pdf: 2279868 bytes, checksum: 4d99a8a04626302078cb68e1b2a75887 (MD5) Previous issue date: 2013-02-01 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Leishmania infantum and Trypanosoma cruzi are trypanosomatids of medical importance and are, respectively, the etiologic agents of visceral leishmaniasis (VL) and Chagas disease (CD) in Brazil. People infected with L. infantum or T. cruzi may develop asymptomatically, enabling the transmission of pathogens through blood transfusion and / or organs. The assessment of the infection by T. cruzi is included among the tests performed for screening blood donors in Brazil, however, there is no availability of tests for Leishmania. Serological tests for T. cruzi are very sensitive, but not specific, and may have cross-reactions with other microorganisms. Thus, the aim of this study was to determine the prevalence of Leishmania infection in blood donors and assess whether the serological test for T. cruzi detect L. infantum. Among the 300 blood samples from donors, discarded in 2011, 61 were T. cruzi positive, 203 were from donors with other infections and 36 were from handbags with low blood volume, but without infection. We also assessed 144 samples from donors without infections and able to donate blood, totaling 444 subjects. DNA was extracted from blood samples of all to perform quantitative PCR (qPCR) to detect Leishmania DNA. The buffy coat obtained from all samples was grown in Schneider medium supplemented and NNN. All samples were evaluated for the presence of anti-Leishmania antibody. The serological results indicate a percentage of 22% of Leishmania infection in blood samples obtained from discarded bags. A total of 60% of samples positive in ELISA for T. cruzi were negative by IFI, used as confirmatory test, ie 60% false positive for Chagas. Among these samples false positive for Chagas, 72% were positive by ELISA for Leishmania characterizing the occurrence of cross reaction between serologic assays. Of the 300 cultures performed, 18 grew parasites that were typed by qPCR and specific isoenzymes, found the species Leishmania infantum crops. Among the 18 cultures, 4 were purged from scholarships for low volume and all negative serology blood bank, thus demonstrating that there is a real risk of Leishmania transmission via transfusion. It is concluded that in an area endemic for leishmaniasis in Brazil, serological diagnosis performed to detect infection by T. cruzi among blood donors can identify infection by L. infantum and although cause false positive for Chagas, this cross-reactivity reduces the risk of Leishmania infection via blood transfusion, since tests are not applied specific detection of the parasite. In this way, there remains the need to discuss the implementation of a specific serological screening test for Leishmania in endemic countries such as Brazil / Leishmania infantum e Trypanosoma cruzi s?o tripanossomat?deos de import?ncia m?dica e s?o, respectivamente, os agentes etiol?gicos da leishmaniose visceral (LV) e da doen?a de Chagas (DC) no Brasil. Pessoas infectadas por L. infantum ou por T. cruzi podem evoluir de forma assintom?tica, possibilitando a transmiss?o destes pat?genos atrav?s de transfus?o sangu?nea e/ou ?rg?os. A avalia??o da infec??o por T. cruzi est? contemplada entre os exames realizados para triagem de doadores no Brasil, no entanto, n?o h? disponibilidade de exames para Leishmania. Os testes sorol?gicos para T. cruzi s?o muito sens?veis, mas n?o espec?ficos, podendo apresentar rea??es cruzadas com outros microorganismos. Desta forma, o objetivo desse estudo foi determinar a preval?ncia da infec??o por Leishmania em doadores de sangue e avaliar se os teste sorol?gicos para T. cruzi detectam L. infantum. Dentre as 300 amostras de sangue de doadores, descartadas em 2011, 61 eram T. cruzi positivas, 203 eram de doadores com outras infec??es e 36 eram oriundas de bolsas com baixo volume de sangue, mas sem infec??o. Foram tamb?m avaliadas 144 amostras de doadores sem infec??es e aptos a doarem sangue, totalizando 444 volunt?rios. DNA foi extra?do do sangue de todas as amostras para realizar PCR quantitativa (qPCR) a fim de detectar DNA de Leishmania. O creme leucocit?rio obtido de todas as amostras foi cultivado em meio Schneider e NNN suplementado. Todas as amostras foram avaliadas quanto a presen?a de anticorpo anti-Leishmania. Os resultados sorol?gicos apontam um percentual de 22% de infec??o por Leishmania nas amostras de sangue obtidas das bolsas descartadas. Um total de 60% das amostras positivas no ELISA para T. cruzi foram negativas na RIFI, teste usado como confirmat?rio, ou seja, 60% falso positivos para Chagas. Dentre essas amostras falso positivas para Chagas, 72% foram positivas no ELISA para Leishmania caracterizando a ocorr?ncia de rea??o cruzada entre os ensaios sorol?gicos. Do total de 300 culturas realizadas, 18 cresceram parasitas que foram tipados por isoenzimas e qPCR espec?fica, sendo encontrada a esp?cie Leishmania infantum nas culturas. Dentre as 18 culturas, 4 foram provenientes de bolsas expurgadas por baixo volume e negativas em todas as sorologias do banco de sangue, demonstrando assim que h? um risco real de transmiss?o de Leishmania por via transfusional. Conclui-se que em ?rea end?mica para leishmanioses no Brasil, diagn?sticos sorol?gicos realizados para detectar infec??o por T. cruzi em doadores de sangue podem identificar a infec??o por L. infantum e, apesar de ocasionar resultados falso positivos para Chagas, essa reatividade cruzada reduz o risco de infec??o por Leishmania via transfus?o sangu?nea, visto que n?o s?o aplicados testes espec?ficos detec??o desse parasita. Desde modo, persiste a necessidade de se discutir a implementa??o de um teste de triagem sorol?gica espec?fico para Leishmania em pa?ses end?micos como o Brasil
15

Comprehensive Forensic Toxicological Analysis of Designer Drugs

Swortwood, Madeleine Jean 21 October 2013 (has links)
New designer drugs are constantly emerging onto the illicit drug market and it is often difficult to validate and maintain comprehensive analytical methods for accurate detection of these compounds. Generally, toxicology laboratories utilize a screening method, such as immunoassay, for the presumptive identification of drugs of abuse. When a positive result occurs, confirmatory methods, such as gas chromatography (GC) or liquid chromatography (LC) coupled with mass spectrometry (MS), are required for more sensitive and specific analyses. In recent years, the need to study the activities of these compounds in screening assays as well as to develop confirmatory techniques to detect them in biological specimens has been recognized. Severe intoxications and fatalities have been encountered with emerging designer drugs, presenting analytical challenges for detection and identification of such novel compounds. The first major task of this research was to evaluate the performance of commercially available immunoassays to determine if designer drugs were cross-reactive. The second major task was to develop and validate a confirmatory method, using LC-MS, to identify and quantify these designer drugs in biological specimens. Cross-reactivity towards the cathinone derivatives was found to be minimal. Several other phenethylamines demonstrated cross-reactivity at low concentrations, but results were consistent with those published by the assay manufacturer or as reported in the literature. Current immunoassay-based screening methods may not be ideal for presumptively identifying most designer drugs, including the “bath salts.” For this reason, an LC-MS based confirmatory method was developed for 32 compounds, including eight cathinone derivatives, with limits of quantification in the range of 1-10 ng/mL. The method was fully validated for selectivity, matrix effects, stability, recovery, precision, and accuracy. In order to compare the screening and confirmatory techniques, several human specimens were analyzed to demonstrate the importance of using a specific analytical method, such as LC-MS, to detect designer drugs in serum as immunoassays lack cross-reactivity with the novel compounds. Overall, minimal cross-reactivity was observed, highlighting the conclusion that these presumptive screens cannot detect many of the designer drugs and that a confirmatory technique, such as the LC-MS, is required for the comprehensive forensic toxicological analysis of designer drugs.
16

Comparação entre Neisseria meningitidis e Neisseria lactamica: cinética do cultivo e potencial antigênico de OMV e frações. / Comparison between Neisseria meningitidis and Neisseria lactamica: kinetics of bacterial growth and analysis of the antigenic potential of OMV and fractions.

Giovanna Ferreira Costa Leão Salustiano 24 April 2015 (has links)
Neste trabalho foi avaliado o potencial antigênico das vesículas de membrana externa, OMV, de N. meningitidis, das OMV e componetes protéicos selecionados de N. lactamica. Para tal foram realizados cultivos de ambas as espécies em biorreatores, ensaios de imunização em camundongos, análises de espectrometria de massas, e análises de tamanho das partículas, polidispersabilidade e potencial zeta. As análises da cinética de cultivos levaram a dados inéditos possibilitando uma nova discussão sobre o metabolismo e sobre a produtividade de OMV destas bactérias. N. lactamica obteve valores 5 vezes maiores de concentração máxima de OMV de 152 mg/L e 2,5 vezes maiores de produtividade de OMV de 0,32 g/L.h comparado aos obtidos para N. meningitidis nas mesmas condições de cultivo. OMV obtidas nos cultivos de ambas e componentes proteicos de N. lactamica foram utilizadas para imunizar camundongos com 3 doses subcutâneas. Ensaios de imunoblote e ELISA demonstraram que soros gerados contra as proteínas isoladas de N. lactamica foram reativos com proteínas de N. meningitidis, assim como o soro anti-OMV de N. lactamica que reagiu com 6 proteínas de N. meningitidis, as proteínas de membrana App, Omp85, PilQ, PorA, PorB, e ComL ou Opa/Opc. Análises de espectrometria de massas identificaram 229 proteínas na OMV de N. lactamica, sendo 77 proteínas de membrana e 243 proteínas de N. meningitidis, sendo 54 proteínas de membrana. Os resultados obtidos neste trabalho sugerem a possibilidade do uso das OMV de Neisseria lactamica como abordagem alternativa para o desenvolvimento de vacinas contra a doença meningocócica. / In these studies we evaluated the antigenic potential of outer membrane vesicles (OMV) from N. meningitidis, OMV from N. lactamica and proteic components from N. lactamica. Outer membrane vesicles were obtained from cultures of both species in bioreactors. Immunization tests were conducted in mice. Western-blotting and ELISA techniques were used to evaluate the cross-reactivity of murine sera against outer-membrane proteins from Neisseria meningitidis and Neisseria lactamica. Analysis of mass spectrometry and determination of particle size, polydispersity and zeta potential were also performed. Analysis of bacterial growth kinetics led to new data enabling a discussion about metabolism and OMV productivity. When both species were cultured in the same medium OMV concentration of N. lactamica (152 mg/L) is 5 times higher than that in N. meningitidis and OMV productivity of N. lactamica (0.32 g/L.h) is 2.5 times higher. Mice were vaccinated subcutaneously with 3 doses of OMV from both species and proteins from N. lactamica. These vaccines induced antibodies against N. meningitidis proteins. By mass spectrometry it was possible to identify these membrane proteins as App, Omp85, PilQ, PorA, PorB, and ComL or Opa/Opc. Mass spectrometry analyses also identified 229 proteins in N. lactamica OMV, with 77 predicted as membrane proteins and 243 in N. meningitidis OMV with 54 predicted as membrane proteins. Ours results suggested that OMV from Neisseria lactamica provides protection against N. meningitidis and could be used as an alternative approach for the development of a vaccine against meningococcal disease.
17

Validation and optimization of multiplexInSitu PLA for signalling pathway analysis

Sinha, Tanay Kumar January 2021 (has links)
With the advent of Tyrosine kinase inhibitors (TKI) as a therapy for Chronic myeloid Leukemia (CML), the patients now enjoy a life expectancy close to that of the general population. But some patients do get unresponsive to the TKI treatment over time due to several mutations in the kinase domain of the BCR-ABL fusion protein, which further leads to activation of multiple signaling cascades within the leukemic cell, helping it survive and proliferate. This project validates and optimizes a new method of In situ PLA that incorporates the usage of different padlocks and template oligos. Multiple cross-reactivity tests and interaction assays in multiple cancer cell lines will further optimize this system as a robust multiplex protein-protein interaction detection tool. Proteins associated with the MAP-K, PI3-K, and Jak-STAT signaling pathways were the main detection targets.
18

Immunological Cross-Reactivity : Construction of a Workflow That Enables Cross-Reactivity Predictions

Blomlöf, Alexander, Unge, Alvin, Byström, Petter, Lindberg, Erika, Fries, Torbjörn January 2022 (has links)
Cross-reactivity occurs when an antibody binds to the epitope of a protein that is not the targeted antigen. This is problematic in the analysis of immunoassay diagnostics. Detecting a protein incorrectly might cause issues such as incorrect mapping of metabolic conditions for research or diagnosis. In this study, articles have been collected within two main fields. The first of which is focused on bioinformatic tools to predict cross-reactivity risk and the second field investigates how single substitutions affect the antibody-antigen binding. The results from the collected articles were analyzed with the aim of providing as much information surrounding the topic as possible, to gain a further understanding of how protein similarities impact cross-reactivity. FASTA alignments proved to be efficient in classifying cross-reactive proteins based on sequence similarity. Moreover, epitope analysis, using PD tool or Cross-React, can provide an even more precise subset of proteins with risk of causing cross-reactivity. Individual residues of the epitopes of the subset can then be analyzed. Specific residue’s physicochemical properties such as hydrophobicity, polarity, size and charge have proven to be relevant for the binding affinity, with charge having the largest impact. The position of an amino acid has also shown great importance. More centrally located amino acids within the epitope contribute more to paratope affinity than those on the outer positions. However, a conclusive classifier based on specific residues within epitopes is difficult to implement in cross-reactivity analysis. A workflow of the different prediction steps has been constructed into a workflow that may be implemented as an automated pipeline in the future.
19

Cross-reactivity among alphaviruses provides insight into viral emergence and novel defense strategies

Webb, Emily Morgan 13 April 2022 (has links)
Alphaviruses are a group of medically relevant arthropod-borne viruses (arboviruses) belonging to the Togaviridae family that are maintained by mosquito vectors. These zoonotic viruses are clustered into two groups: New World and Old World, depending on their geographical origin/distribution and clinical manifestations. Both of these groups cause disease symptoms of an acute febrile illness; however, each group has a distinct, hallmark disease symptom; New World alphaviruses, such as Eastern, Western, and Venezuelan equine encephalitis viruses (EEEV, WEEV, and VEEV, respectively), present with severe encephalitis while Old World alphaviruses, such as Sindbis, chikungunya, and Mayaro viruses (SINV, CHIKV, and MAYV, respectively) present with an incapacitating polyarthralgia that can persist for years following initial infection. To date, the most effective means of controlling these arboviral infections is through mosquito control programs. However, these programs have crucial limitations in their effectiveness; therefore, novel approaches are necessary to control the spread of these crippling pathogens and lessen their disease burden. Given the close phylogenetic and antigenic relationship between MAYV and CHIKV, we hypothesized that prior CHIKV immunity may affect the outcome of MAYV disease and/or limit its emergence in humans. Our work has shown that anti-CHIKV neutralizing antibodies can provide cross-protective immunity against MAYV disease. Alongside these studies, we have characterized the potency of a camelid-derived single-domain antibody (sdAb) that neutralizes a breadth of alphaviruses, including CHIKV and MAYV. With these data, we have designed and generated transgenic Aedes aegypti mosquitoes that express two anti-CHIKV sdAbs to target infection, dissemination, and transmission of MAYV and CHIKV within this deadly vector. These findings are particularly significant because they highlight the ability to co-target two emerging alphaviruses that are crippling public health and obliterating quality of life around the globe within a single defense strategy. / Doctor of Philosophy / Alphaviruses are arthropod-borne viruses (arboviruses) belonging to the Togaviridae family that infect millions of people annually via the bite of female mosquitoes. These viruses are major public health threats due to their ability to infect humans and animals and infections resulting in a range of debilitating diseases. Viruses within this genus are clustered into two groups: Old World and New World, based on geographical origin and distribution. While New World alphaviruses are known for inducing severe encephalitis (i.e., swelling in the brain), a hallmark symptom of the Old World alphaviruses is the development of incapacitating polyarthralgia (i.e., widespread joint pain) that can persist for years following initial infection. To date, the most effective means of combatting these viruses is through mosquito control programs. However, these programs have crucial limitations in their effectiveness; therefore, novel approaches are necessary to control the spread of these crippling pathogens. Given the close genetic relationship between chikungunya virus (CHIKV) and Mayaro virus (MAYV), our research has focused on harnessing cross-reactive immunity between these emerging alphaviruses. We discovered this cross-reactivity provides protective immunity to both viruses (i.e., CHIKV and MAYV) after exposure to only one (i.e., CHIKV) of the viruses. Next, we characterized the potency of a small, single-domain antibody (sdAb) to neutralize a breadth of alphaviruses, including CHIKV and MAYV. With these data, we have designed and generated transgenic Aedes aegypti mosquitoes that express this sdAb to target both CHIKV and MAYV within this deadly mosquito vector. These findings are particularly significant because they provide the foundation for a novel approach to controlling and preventing outbreaks of these emerging alphavirus pathogens that obliterate quality of life in public health settings around the globe.
20

Développement et applications d’un outil bio-informatique pour la détection de similarités de champs d’interaction moléculaire / Development and applications of a bioinformatic tool to detect molecular interaction field similarities

Chartier, Matthieu January 2016 (has links)
Résumé : Les méthodes de détection de similarités de sites de liaison servent entre autres à la prédiction de fonction et à la prédiction de cibles croisées. Ces méthodes peuvent aider à prévenir les effets secondaires, suggérer le repositionnement de médicament existants, identifier des cibles polypharmacologiques et des remplacements bio-isostériques. La plupart des méthodes utilisent des représentations basées sur les atomes, même si les champs d’interaction moléculaire (MIFs) représentent plus directement ce qui cherche à être identifié. Nous avons développé une méthode bio-informatique, IsoMif, qui détecte les similarités de MIF entre différents sites de liaisons et qui ne nécessite aucun alignement de séquence ou de structure. Sa performance a été comparée à d’autres méthodes avec des bancs d’essais, ce qui n’a jamais été fait pour une méthode basée sur les MIFs. IsoMif performe mieux en moyenne et est plus robuste. Nous avons noté des limites intrinsèques à la méthodologie et d’autres qui proviennent de la nature. L’impact de choix de conception sur la performance est discuté. Nous avons développé une interface en ligne qui permet la détection de similarités entre une protéine et différents ensembles de MIFs précalculés ou à des MIFs choisis par l’utilisateur. Des sessions PyMOL peuvent être téléchargées afin de visualiser les similarités identifiées pour différentes interactions intermoléculaires. Nous avons appliqué IsoMif pour identifier des cibles croisées potentielles de drogues lors d’une analyse à large échelle (5,6 millions de comparaisons). Des simulations d’arrimage moléculaire ont également été effectuées pour les prédictions significatives. L’objectif est de générer des hypothèses de repositionnement et de mécanismes d’effets secondaires observés. Plusieurs exemples sont présentés à cet égard. / Abstract : Methods that detect binding site similarities between proteins serve for the prediction of function and the identification of potential off-targets. These methods can help prevent side-effects, suggest drug repurposing and polypharmacological strategies and suggest bioisosteric replacements. Most methods use atom-based representations despite the fact that molecular interaction fields (MIFs) represents more closely the nature of what is meant to be identified. We developped a computational algorithm, IsoMif, that detects MIF similarities between binding sites. We benchmark IsoMif to other methods which has not been previously done for a MIF-based method. IsoMif performed best in average and more consistently accross datasets. We highlight limitations intrinsic to the methodology or to nature. The impact of design choices on performance is discussed. We built a freely available web interface that allows the detection of similarities between a protein and pre-calculated MIFs or user defined MIFs. PyMOL sessions can be downloaded to visualize similarities for the different intermolecular interactions. IsoMif was applied for a large-scale analysis (5,6 millions of comparisons) to predict offtargets of drugs. Docking simulations of the drugs in the binding site of their top hits were performed. The primary objective is to generate hypotheses that can be further investigated and validated regarding drug repurposing opportunities and side-effect mechanisms.

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