Binder-based assays are employed throughout the life sciences. Powerful signal amplification techniques have enabled detection of very rare molecule species diluted in simple buffers. Unspecific binding of primary binders leads to increased background in more complex samples. By requiring two recognition events, ligation-based molecular analyses provide highly specific detection of biomolecules in complex samples. We developed a highly multiplexed padlock-ligation assay targeting signature sequences in the hemagglutinin and neuraminidase genes. From a panel of 77 avian influenza isolates of all major serotypes, 97% were genotyped correctly in accordance with previous classifications by classical diagnostic methods (Paper I). Alternative splicing is an important mechanism expanding the proteome. Current analysis techniques fail to provide sequences of complete transcripts beyond the read length of sequencing instruments. We devised and implemented a strategy to compress the sequence information contained in the splicing pattern of a transcript into the presence or absence of sequence-blocks. We demonstrate that this assay yields information about the splicing patterns in thousands of transcripts from cellular cDNA (Paper II). Expression changes of mucin proteins and glycosylation structures are frequently observed from the early stages of cancer development. Expression of mucin 2 and sialyl-Tn are common features of intestinal metaplasia and gastric cancer, and are known to co-locate. Here we have developed an in situ proximity ligation assay (PLA) directed against mucin 2 and sialyl-Tn. Our study on intestinal metaplasia and gastric cancer tissue sections identified mucin 2 as a major carrier of sialyl-Tn in these conditions, and demonstrated how conveniently glycosylation of proteins can be studied by in situ PLA (Paper III). This thesis shows how the dual recognition requirement of ligation-based assays can be employed to detect target molecules with high specificity, to analyze several sequence features of nucleic acids or to study the proximity of two antigens in situ.

Non invasive in vivo imaging will lead to better understanding of Angiotensin II Type 1 Receptor’s (AT1R) role in disease progression and may guide therapy in cardiovascular patients. Two models were used in this project: 5/6 nephrectomy and transient left anterior descending (LAD) ligation. Rats were scanned with [13N]ammonia and [11C]methyl-candesartan, both of which are Positron Emission Tomography (PET) tracers, at 8 weeks (nephrectomy) and 2 weeks (LAD ligation) after surgery. Western blot analysis was used to corroborate PET data. Nephrectomy: Renal AT1R image analysis displayed a 40% decrease in kidney AT1R in nephrectomized animals compared to sham (p<0.05) which was confirmed with Western blot and biodistribution. LAD ligation: Left Ventricle AT1R Western blot analysis exhibited a 60% increase in 20min ligation (p<0.05) with maintained myocardial blood flow. In conclusion, changes in renal AT1R were successfully imaged using [11C]methyl-candesartan in nephrectomized animals, and 20min LAD ligation/reperfusion is an appropriate model to image an increase in cardiac AT1R following ischemic injury.

Non invasive in vivo imaging will lead to better understanding of Angiotensin II Type 1 Receptor’s (AT1R) role in disease progression and may guide therapy in cardiovascular patients. Two models were used in this project: 5/6 nephrectomy and transient left anterior descending (LAD) ligation. Rats were scanned with [13N]ammonia and [11C]methyl-candesartan, both of which are Positron Emission Tomography (PET) tracers, at 8 weeks (nephrectomy) and 2 weeks (LAD ligation) after surgery. Western blot analysis was used to corroborate PET data. Nephrectomy: Renal AT1R image analysis displayed a 40% decrease in kidney AT1R in nephrectomized animals compared to sham (p<0.05) which was confirmed with Western blot and biodistribution. LAD ligation: Left Ventricle AT1R Western blot analysis exhibited a 60% increase in 20min ligation (p<0.05) with maintained myocardial blood flow. In conclusion, changes in renal AT1R were successfully imaged using [11C]methyl-candesartan in nephrectomized animals, and 20min LAD ligation/reperfusion is an appropriate model to image an increase in cardiac AT1R following ischemic injury.

The extent of devastation caused by a biological warfare attack is highly correlated to the time from release to detection. As a step towards lowering the detection time the international project TWOBIAS was launched. Here, the main goal is to develop an automated, specific and sensitive combined detection and identification instrument capable of identifying a biological threat within an hour. The identification unit is comprised of a sample preparation module, an amplification module and a detection module and utilizes a proximity ligation assay in combination with circle-to-circle amplification in order to detect a biological threat. This thesis describes the automation of the sample preparation steps of the assay and the integration with the downstream units. The functionality of the sample preparation module was verified by subjecting it to biological samples in a laboratory and at a real-life location. The results showed that the sample preparation module was capable of preparing a sample collected in a complex environment with the same results as a sample prepared in a laboratory.

Les interactions multivalentes sucre/protéine sont impliquées dans de nombreux processus biologiques tels que l'adhésion hôte-pathogène, la communication cellulaire ou les réponses immunitaires. La conception de glycoconjugués capables de présenter des motifs osidiques en cluster est essentielle, non seulement pour étudier ces phénomènes de reconnaissance complexes mais aussi pour développer des agents biologiquement actifs. Dans ce contexte, l'objectif de ma thèse a été de synthétiser de nouveaux glycoclusters et d'évaluer leurs propriétés biologiques. Ces glycoclusters ont été obtenus en conjuguant des sucres sur des cyclopeptides par des méthodes chimiosélectives (cycloaddition de Huisgen et ligation oxime). Des composés tetravalents, hexavalents et hexadécavalents d'architectures et de compositions variables ont été synthétisés, entièrement caractérisés puis évalués au laboratoire ou dans le cadre de collaborations avec différentes cibles. Un glycocluster hexadécavalent fucosylé a ainsi pu être identifié comme puissant inhibiteur de l'interaction de la lectine PA-IIL de la bactérie Pseudomonas aeruginosa à une concentration subnanomolaire. Une autre famille de composés associant des sucres et des peptides a montré des propriétés immunologiques uniques, notamment pour activer les cellules NK contre des cellules cancéreuses sans déclencher de phénomène d'autoapoptose. Mots clés : chimie des sucres, chimie des peptides, glycoclusters, ligations chimiosélectives, interactions sucre-protéine, lectine, cellule NK.

Non invasive in vivo imaging will lead to better understanding of Angiotensin II Type 1 Receptor’s (AT1R) role in disease progression and may guide therapy in cardiovascular patients. Two models were used in this project: 5/6 nephrectomy and transient left anterior descending (LAD) ligation. Rats were scanned with [13N]ammonia and [11C]methyl-candesartan, both of which are Positron Emission Tomography (PET) tracers, at 8 weeks (nephrectomy) and 2 weeks (LAD ligation) after surgery. Western blot analysis was used to corroborate PET data. Nephrectomy: Renal AT1R image analysis displayed a 40% decrease in kidney AT1R in nephrectomized animals compared to sham (p<0.05) which was confirmed with Western blot and biodistribution. LAD ligation: Left Ventricle AT1R Western blot analysis exhibited a 60% increase in 20min ligation (p<0.05) with maintained myocardial blood flow. In conclusion, changes in renal AT1R were successfully imaged using [11C]methyl-candesartan in nephrectomized animals, and 20min LAD ligation/reperfusion is an appropriate model to image an increase in cardiac AT1R following ischemic injury.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Sepsis is recognized as a systemic inflammatory response (SIRS) to infection with the presence of progressive tissue damage, where multiple organ failure is the most severe expression. The purinergic signaling plays an important role in inflammatory response modulation as well as in immune responses through its extracellular biomolecules, such as adenine nucleotides and its derivative nucleoside adenosine. These signalling molecules are released by cells in response to damage or cellular stimuli induced by pathogens. Adenine nucleotides and adenosine effects are promoted by activation of specific purinergic receptors controlled by an enzymatic cascade on cell surface. In addition to immunologic changes, oxidative stress has an important part in sepsis pathophysiology, contributing to its deleterious systemic effects such as tissue hypoxia and organ failure. This study aims to evaluate the activity of the E-NTPDase, which degrade adenine nucleotides in lymphocytes, as well as analyse the oxidative profile in brain, heart, liver and kidney in rats submitted to experimental sepsis. The sepsis was induced by cecal ligation and puncture (CLP). The evaluation of the effects of sepsis on E-NTPDase activity in lymphocytes, as well as on the oxidative stress parameters in different tissues, was divided into two stages. On the first stage, the animals were split into two groups: (1) negative controls and (2) septic, which evaluated the activity of the E-NTPDase and histological analysis of the kidneys, liver and lung. On the second stage, the animals were divided into three groups: (1) negative controls, (2) sham e (3) septic. An increase in ATP hydrolysis was observed in sepsis-induced rats when compared to the control group. Nevertheless, the E-NTPDase activity remained unchanged when ADP was applied as substrate. Histological analyses of kidneys, liver and lung have shown vascular congestion, necrosis and inflammatory mononuclear cell infiltration when compared to control group. Regarding the antioxidant activity, no difference was observed in the NPSH content and SOD activity in the organs analysed. Concerning the oxidative stress parameters, the carbonyl protein content showed no significant difference in brain and liver, whilst in heart and kidney a decrease was observed in the septic group. No significant difference in TBARS levels was observed in brain, however an increase was observed in kidney while a decrease was observed in heart and liver. E. coli was identified as the etiological agent. On the septic group, significant hematological changes such as leucocytosis and thrombocytopenia were observed. This reduction in TBARS levels in heart and liver does not agree with data on the literature; this may be due to the employment of different induction techniques among studies, added to altered neutrophil function and and also the characteristics inherent to the pathogenic microorganism. Our findings suggest that the increase in ATP hydrolysis in induced sepsis may be a dynamic response in order to eliminate the increased ATP levels resulting from cell death. Regarding the oxidative stress parameters, the reduction in heart and liver may be due differences in the sepsis induction of CLP model by between different research groups added to altered neutrophil function and and also the characteristics inherent to the pathogenic microorganism. / A sepse pode ser definida como síndrome da resposta inflamatória sistêmica (SIRS) decorrente da reação do sistema imunológico à infecção, denotando um processo progressivo de dano tecidual, onde a disfunção múltipla dos órgãos é a expressão mais grave. O sistema de sinalização purinérgica desempenha um papel importante na modulação das respostas inflamatórias e imunes através de biomoléculas extracelulares, como os nucleotídeos de adenina e seu derivado nucleosídeo adenosina. Essas moléculas sinalizadoras são liberadas do meio intracelular em resposta ao dano ou ao estímulo celular por ação de patógenos. Os efeitos dos nucleotídeos de adenina e da adenosina são promovidos através da ativação de receptores purinérgicos específicos e controlados por uma cascata enzimática localizada na superfície das células. Além das alterações imunes, o estresse oxidativo desempenha um importante papel na patofisiologia desta doença, contribuindo para os principais efeitos sistêmicos deletérios da sepse como a hipóxia tecidual e a falência de órgãos. Sendo assim, visando à melhor compreensão desta patologia, este trabalho teve por objetivo avaliar a atividade da enzima E-NTPDase em linfócitos bem como analisar o perfil oxidativo em cérebro, coração, fígado e rins em ratos submetidos à sepse experimental utilizando a técnica de ligação e perfuração do ceco (CLP). Os procedimentos para avaliação dos efeitos da sepse sob a atividade das enzimas ENTPDase em linfócitos e sob os parâmetros de estresse oxidativo nos tecidos foram divididos em duas etapas. Na primeira etapa, os animais foram divididos em dois grupos: (1) controle negativo e (2) séptico, onde se avaliou a atividade da E-NTPDase e a análise histológica dos rins, fígado e pulmão. Para a segunda etapa, os animais foram divididos em 3 grupos: (1) controle negativo, (2) Sham e (3) séptico, na qual se determinou os parâmetros de estresse oxidativo, bem como o perfil bacteriano e hematológico. Observou-se um aumento na hidrólise de ATP em ratos com sepse induzida quando comparado ao grupo controle. Contudo, a atividade da E-NTPDase não foi alterada, quando utilizado ADP como substrato. Pelas análises histológicas de rins, fígado e pulmão verificou-se no grupo séptico a presença de congestão vascular, necrose e infiltrado inflamatório mononuclear quando comparados com o grupo controle. Em relação à atividade antioxidante não se observou diferença significativa no conteúdo de NPSH e na atividade da SOD em nenhum órgão analisado. Quanto aos parâmetros do estresse oxidativo, o teor de proteína carbonil não apresentou diferença significativa no cérebro e no fígado enquanto nos tecidos cardíaco e renal observou-se um decréscimo no grupo séptico em relação aos demais grupos. Não foi observada nenhuma diferença significativa nos níveis de TBARS no cérebro, no entanto, estes níveis estavam reduzidos no coração e no fígado e aumentados no tecido renal. Foi identificado como agente etiológico da sepse E. coli. Observou-se significativas alterações hematológicas no grupo séptico como: leucocitose e trombocitopenia. Com o presente trabalho conclui-se que, na sepse induzida, o aumento da hidrólise do ATP seja provavelmente consequência de uma resposta dinâmica para reduzir os níveis elevados de ATP resultantes da morte celular. Já a redução nos parâmetros de estresse oxidativo no coração e no fígado pode ter ocorrido devido a diferenças na indução da sepse pelo modelo CLP entre os diferentes grupos de pesquisa, adicionado à função dos neutrófilos alterados e também às características inerentes do tipo de micro-organismo patogênico.

Embora esteja comprovada a superioridade da ligadura elástica sobre a esclerose endoscópica na profilaxia secundária da hemorragia varicosa, ainda há discussão se esta vantagem também é observada no tratamento da fase aguda do sangramento. O presente estudo tem como objetivo comparar os resultados da ligadura elástica com a esclerose endoscópica em pacientes admitidos no Pronto-Socorro (PS) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCFMUSP) por hemorragia digestiva alta provocada por rotura de varizes de esôfago. Tratase de estudo unicêntrico, prospectivo, com alocação aleatória dos pacientes sem crossover. A fim de se detectar diferença de 20% entre a capacidade de hemostasia de cada um dos métodos, cada grupo deveria ser constituído por 260 pacientes, considerando poder estatístico de 80% e nível de significância inferior a 5%. Após diagnóstico endoscópico de rotura de varizes de esôfago, foi realizado sorteio para inclusão dos pacientes em dois grupos: esclerose endoscópica (EE) x ligadura elástica (LE). A esclerose foi realizada através da injeção intravasal de oleato de etanolamina a 3%, em alíquotas de 5ml, acima e abaixo do ponto de ruptura, respeitando o valor máximo por sessão de 20ml. No grupo LE, procurou-se ligar a variz sobre o ponto de ruptura. Se isto não foi possível, procurou-se ligar todo o tecido varicoso dos 3cm finais do esôfago. Foi utilizado o kit de ligadura MBL-6 e cateter VINF 23 (Cook, E. Tamusssino). As variáveis estudadas foram: a taxa de hemostasia inicial (até 5 dias), recidiva hemorrágica precoce (5 dias a 6 semanas), complicações e mortalidade. De maio de 2005 a maio de 2007, foram admitidos, no PS do HCFMUSP, 480 pacientes com hemorragia digestiva alta (HDA) provocada por hemorragia varicosa esofágica. Destes, 380 foram excluídos pelos seguintes motivos: mais de um tratamento prévio com ligadura ou esclerose (n=180), não randomização (n=85), uso de outra técnica hemostática como adesivo tissular de cianoacrilato (n=62) ou tratamento clínico incompleto no momento do exame endoscópico (n=53). Cem pacientes, 50 no grupo EE e 50 no LE foram incluídos no estudo. Destes, 72 eram homens e 28 mulheres, média de idade 52 anos. Os grupos se mostraram homogêneos quanto ao sexo, idade, Child-Pugh, hemoglobinemia à admissão, presença de choque hipovolêmico e calibre das varizes. Não foram encontradas diferenças estatisticamente significantes entre os grupos com relação ao controle inicial do sangramento (5 dias), ressangramento precoce (5 dias a 6 semanas), complicações e mortalidade (9 no grupo EE e 10 no grupo LE). Ao final de 6 semanas, 36 (80%) pacientes no grupo esclerose e 33 (77%) no grupo ligadura elástica estavam vivos e sem sinais de sangramento. Foi encontrada associação estatisticamente significante entre a classificação de Child-Pugh e mortalidade (p<0,001), que foi de 16% nos graus A ou B e 84% nos pacientes Child-Pugh C. Os resultados obtidos com esta casuística limitada sugerem que EE e a LE são igualmente eficazes no controle da hemorragia varicosa aguda. / Despite the superiority of banding over endoscopic sclerosis for secondary prophylaxis of variceal bleeding, there is still debate if this advantage is also observed for the acute bleeding setting. The study aims to compare band ligation (BL) with endoscopic sclerosis (SCL) in patients admitted to the emergency unit for rupture of esophageal varices. Prospective study carried out in a single center, with random allocation of the patients without crossover. In order to detect a 20% difference between the results of each method, each group should consist of 260 patients, considering an 80% statistical power and level of significance less than 5%. After an endoscopic diagnosis of rupture of esophageal varices, the patients were randomly allocated in two groups: SCL and BL. Sclerosis was performed by ethanolamine oleate intravascular injection, above and below the rupture point (maximum volume of 20 ml). In the BL group, banding was attempted at the point of rupture followed by ligation of the whole variceal tissue of the distal esophagus. Six-shooter® and VINF23® catheter (Cook, W. Salem, USA) were employed. Studied variables were initial failure in control bleeding (5 days), early rebleeding rates (5 days to 6 weeks), complications and mortality. From May 2005 to May 2007, 480 patients with an episode of variceal bleeding were admitted to the emergency room. From them, 380 were excluded because more than one previous treatment with SCL or BL (n=180), non-randomization (n=85), the use of another hemostatic technique such as cyanoacrylate tissular adhesive (n=62) and incomplete clinical treatment (n=53).One hundred patients, 50 in the SCL and 50 in the BL group were included in the study (72 male, 28 female, mean age 52 years). No differences between the groups were detected regarding gender, age, Child-Pugh status, the presence of shock at admission, mean hemoglobin levels and varices size. No statistically significant differences were found between the groups regarding control bleeding (5 days) and early rebleeding rates (5 days to 6 weeks), complications and mortality (9 in the SCL vs. 10 in the BL group). By the end of 6 weeks 36 (80%) patients in the SCL group and 33 (77%) in the EBL group were alive and free of bleeding. A statistically significant association was found between Child-Pugh status and mortality (p<0,001), which was 16% for A and B grades and 84% for grade C patients. The results obtained with this limited number of patients suggest that SCL and BL are equally efficient in the control of acute variceal bleeding.

INTRODUÇÃO: Estudos recentes têm demonstrado que ocorre geração normal de trombina na cirrose hepática mesmo nos pacientes com diminuição da atividade de protrombina e plaquetopenia, de forma que a utilidade dos testes convencionais de coagulação em predizer o risco de sangramento associado a procedimentos seria questionável. OBJETIVO: O objetivo principal deste estudo foi avaliar se as alterações dos parâmetros de coagulação influenciam a frequência e gravidade do sangramento por úlcera após ligadura elástica de varizes de esôfago. CASUÍSTICA E MÉTODOS: Neste estudo prospectivo de coorte realizado no período de dois anos, no Hospital das Clínicas da Faculdade de Medicina da USP, foram incluídos 150 pacientes com o diagnóstico de cirrose hepática, encaminhados para realização de ligadura elástica como profilaxia primária (n=45) e secundária (n=105) de sangramento por varizes de esôfago. Os critérios de inclusão foram: a) presença de varizes de esôfago de médio ou grosso calibre; b) idade superior a 18 anos; c) concordância em participar do estudo. Os critérios de exclusão foram: a) doenças pulmonares e cardíacas graves ou síndrome hepatorrenal associada; b) carcinoma hepatocelular avançado; c) insuficiência renal com uremia; d) doenças ou uso de drogas que alteram a coagulação sanguínea. Foram analisados em todos os pacientes: International Normalized Ratio (INR), tempo de tromboplastina parcial ativada e contagem de plaquetas. Em 92 pacientes foram avaliados: atividade do fator V, fator de von Willebrand, fibrinogênio, proteínas C e S, dímero-D e tromboelastografia. Os pacientes foram estratificados de acordo com: a) grau de disfunção hepática, avaliado pela classificação de Child-Pugh [Child A, n=74 (49%); Child B, n=42 (28%); Child C, n=34 (23%)]; b) valores de corte de INR [>1,5 (n=28); 1,5 (n=122)]; e plaquetas [<50x103/mm3(n=18); 50x103/mm3 (n=132)]; c) padrões da tromboelastografia; d) valores e/ou atividade dos fatores pró-coagulantes e anticoagulantes naturais. As sessões de ligadura foram realizadas a cada 2 semanas. Os dados de cada paciente foram registrados até dois meses após erradicação das varizes. RESULTADOS: Onze pacientes apresentaram sangramento por úlcera após LE. Sangramento ocorreu em cinco pacientes com Child A/B (4,3%) e em 6 pacientes com Child C (17%) (p=0,0174 para Child A/B versus Child C). Oito pacientes (7,3%) apresentaram sangramento entre os 110 pacientes com valores de corte tradicionalmente considerados seguros para INR e plaquetas e apenas três (7,5%) entre os 40 pacientes com valores de risco (p=1,0). Dentre os 92 pacientes com testes expandidos de coagulação, o sangramento ocorreu em cinco. Não houve diferença em nenhum dos parâmetros de coagulação incluindo os padrões da tromboelastografia entre os pacientes com e sem sangramento. CONCLUSÕES: O sangramento por úlcera após ligadura elástica de varizes de esôfago foi associado com o grau de disfunção hepática (Child C), mas não com os fatores convencionais ou expandidos da coagulação em pacientes cirróticos sem insuficiência renal ou infecção submetidos à ligadura elástica eletiva. Estes resultados tornam discutível a necessidade de administração profilática de agentes pró-coagulantes previamente a procedimentos invasivos eletivos / BACKGROUND & AIMS. There is controversy over whether coagulation status predicts bleeding caused by ulceration after esophageal varices band ligation (EVL). METHODS: EVL was performed for primary (n=45) or secondary (n=105) prophylaxis in 150 patients with cirrhosis (Child A, n=74 [49%]; Child B, n=42 [28%]; Child C, n=34 [23%]). International Normalized Ratio (INR) and platelet counts (PC) were assessed in all. In 92 patients, levels of factor V, fibrinogen, D-dimer, protein C and protein S, von Willebrand factor and thromboelastography (TEG) were assessed. PC <50x103/mm3 and INR >1.5 were considered high-risk cutoffs for bleeding. Conversely, PC 50x103/mm3 with INR 1.5 were safe cutoffs. RESULTS: Overall, 11 patients (7.3%) had post-EVL ulcer bleeding. Bleeding occurred in 5 patients with Child A/B (4.3%) and 6 patients with Child C (17%) (p=0.0174 for Child A/B versus Child C). Eight patients with bleeding were among the 110 below the cutoff for INR and PC, whereas only 3 of the patients with bleeding were among the 40 patients with purported high-risk values (p=1.0). Among the 92 patients with expanded coagulation tests, bleeding occurred in 5. There was no difference in any of the coagulation parameters, including overall TEG patterns, between patients who did and did not bleed. CONCLUSION: Post-EVL ulcer bleeding was associated with Child C status but not with conventional or expanded coagulation indices in cirrhotic patients without renal failure or infection undergoing elective EVL. These results call into question the common use of prophylactic procoagulants in the elective setting. common use of prophylactic procoagulants in the elective setting

Une des principales limites de la chimiothérapie du cancer est le manque de sélectivité des agents cytotoxiques vis-à-vis des cellules tumorales, entrainant de nombreux effets secondaires. L’intérêt de la vectorisation est d’administrer l’agent cytotoxique sélectivement aux cellules cancéreuses et ainsi d’éviter de faire subir l’action du médicament aux cellules saines. Cette thèse a pour but de synthétiser des prodrogues multivalentes qui utilisent la sous unité B de la toxine de Shiga (STxB) comme agent de vectorisation, ciblant préférentiellement les cellules cancéreuses Gb3-positives. Les deux agents cytotoxiques choisis, un dérivé de la camptothécine et de l’auristatine, ont été liés de façon covalente auvecteur via un espaceur bifonctionnel clivable par le glutathion. L’espaceur a également été remplacé par un répartiteur multivalent susceptible de délivrer une quantité plus importante d’agent cytotoxique à l’intérieur des cellules tumorales.Parallèlement à ce projet de vectorisation d’un agent thérapeutique, des sondes IRM capables de marquer in vivo les tumeurs possédant à leur surface le récepteur Gb3 ont été synthétisées. L’IRM a une très bonne définition spatiale, mais souffre d’un manque de sensibilité. Pour augmenter le contraste, nous avons utilisé une stratégie reposant sur lamultivalence des espaceurs liés à des molécules de DOTA-Gd, un agent de contraste classiquement utilisé en IRM. Ces dernières ont été fixées à STxB via un répartiteur multivalent (des nano-bâtonnets d’or). Le signal IRM est plus intense et donc plus facile à détecter. Enfin, nous avons développé une nouvelle méthode chimique basée sur la ligationoxime pour optimiser la création de conjugués entre STxB et des antigènes comme outils de vaccination. Le conjugué STxB-ovalbumine a permis une meilleure présentation de l’antigène par les cellules dendritiques, conduisant chez la souris à une induction efficace de lymphocytes T. / Pas de résumé en anglais