The aims of this project were to investigate the effect of immune complexes on mononuclear phagocytes in the presence or absence of infection with the human immunodeficiency virus (HIV). Mono Mac 6 (MM6) cells and human monocyte-derived macrophages (MDM) were used to compare the effect of chemical stimulants, cytokines and immune complexes on surface antigen expression. The same experiments were performed using HIV-infected cells to determine the effect of HIV infection on these parameters. Some of the stimulants especially IL-6, IL-10, TNF-alpha and HIV increased CD80 expressions, the effect being greater in MDM than MM6 cells. This has implications for antigen presentation. Cytokines caused the differentiation of MM6 cells and significantly increased or decreased surface antigen expressions. The MM6 cells express surface antigens at lower levels then MDM this indicates that MM6 cells need to differentiate before expressing surface antigens. The high standard deviations obtained meant that no significant change in surface antigen expression was seen in all HIV non-infected and infected MDM incubated with various immune complexes and HIV-sera. Comparing whole blood incubated with KLH and rabbit anti-human IgG showed that both seemed to produce IL-10 and IL-6 early. Only rabbit complexes stimulated TNF-a release. MDM incubated with IL-6, IL-10, and TNF-alpha showed increased expression of CD16 and CD80 only at day 3. However, HIV proteins (CHO) incubated in whole blood caused a significantly release of IL-6 at 8 hours with no detection of IL-10 and TNF-alpha. MM6 infected with HIV-1 Ba-L for 5 days showed increased expression of CD16 and CD11c, but reduced expression of the other antigens examined. Significant levels of IL-10 were released at 8 and 12 hours with a slight increase in IL-6, and TNF-alpha. HIV protein-containing (CHO) immune complexes slightly increased IL-6 secretion at 8 hours at which point, IL-10 production was high. HIV- infected cells incubated with HlV-sera showed a lack of TNF-alpha release but IL-6 and IL-10 was detected at 12 and 8 hours respectively. The detection of high levels of IL-10 and the inhibition of TNF-alpha production may stimulate progression to full blown AIDS.

The area of self-esteem in people with learning disabilities has been largely neglected, and previous researchers have employed a variety of approaches. It is important to further our understanding in the context of providing appropriate clinical interventions and in monitoring the effect of social policy developments on the individuals at the receiving end of service provision. The study aimed to assess the reliability and validity of a set of measures devised specifically for use with learning disabled people, by Szivos-Bach (1993). The measures assess social comparisons, perception of stigma and aspirations and expectations. The study was carried out with 30 adults with mild and moderate learning disabilities between the ages of 18 and 65. The results provide initial support for the social comparisons test as a measure of self-esteem. Less evidence was found for the stigma questionnaire and the aspirations-expectations test. The results are discussed in the light of comparable research into self-esteem measures with non-learning disabled populations. Further research is required, and the most profitable way forward seems to be development of multi-dimensional measures of self-esteem.

The antibody response has evolved under constant pressure to recognize common pathogens and also remain adaptable to novel threats. Given the limited size of the germline antibody repertoire, adaptability requires that some antibodies must be polyspecific for multiple distinct antigens. Despite the profound importance of polyspecificity in the antibody response, the structural features that allow it are not well understood. Antibodies raised against glycoconjugates of Chlamydiaceae LPS oligosaccharides of the inner-core sugar Kdo (3-deoxy-d-manno-oct-2-ulosonic acid) have been shown to cross-react with several inner-core oligosaccharides through conserved recognition of single Kdo residues in a germline-encoded pocket, with additional sugars accommodated by flexible side-chains. Two of these antibodies, S25-2 and S25-39, were observed to bind several Kdo oligosaccharides with an identical binding site conformation, but adopted unique conformations of the heavy chain complementarity determining region loop 3 (CDR H3) in the absence of ligand. Conformational flexibility of germline antibodies is believed to facilitate polyspecificity by generating multiple unique binding sites in a single antibody. This thesis research further explores the conformational flexibility of the antibodies S25-2 and S25-39 to gain insight into mechanisms of antigen recognition and how this feature may allow polyspecificity. This was achieved first by solving structures of S25-39 from crystals grown in unique conditions to observe alternate CDR H3 conformations, and second by designing synthetic Kdo-based antigens so as both to inhibit interaction with the previously observed liganded conformation of S25-2 and S25-39 and to be accommodated by their observed unliganded conformations. These structures reveal an unprecedented level of structural diversity of CDR H3, notably including the exact ‘liganded’ conformation in the absence of ligand. This is the first direct structural evidence that CDR H3 can exist in a conformational equilibrium with antigen binding through a selection mechanism, as opposed to induced fit where antigen causes the observed conformational change. Definitive evidence for binding the synthetic antigens was not obtained, however the resulting structures revealed several additional unique conformations of CDR H3 suggesting that ligands can alter conformational equilibria during crystallization. A unique conformation was also observed with CDR H3 coordinating multiple iodide ions, revealing another potential source of polyspecificity with unique binding paratopes generated by ion coordination. Finally, the unparalleled level of conformational diversity observed for these antibodies highlights the challenges of antibody structure classification and prediction, and stresses the need for additional in-depth studies of conformational diversity and binding mechanisms to advance these fields for therapeutic application. This is the first targeted structural study of flexibility in antibodies and provides insight into their conformational dynamics and antigen-binding mechanisms. These are of fundamental importance in understanding antibody structure and function, a critical consideration in practical applications such as modelling and design of therapeutic or diagnostic antibodies. / Graduate / 2019-11-27

No description available.

abstract: Immunotherapy has been revitalized with the advent of immune checkpoint blockade treatments, and neo-antigens are the targets of immune system in cancer patients who respond to the treatments. The cancer vaccine field is focused on using neo-antigens from unique point mutations of genomic sequence in the cancer patient for making personalized cancer vaccines. However, we choose a different path to find frameshift neo-antigens at the mRNA level and develop broadly effective cancer vaccines based on frameshift antigens. In this dissertation, I have summarized and characterized all the potential frameshift antigens from microsatellite regions in human, dog and mouse. A list of frameshift antigens was validated by PCR in tumor samples and the mutation rate was calculated for one candidate – SEC62. I develop a method to screen the antibody response against frameshift antigens in human and dog cancer patients by using frameshift peptide arrays. Frameshift antigens selected by positive antibody response in cancer patients or by MHC predictions show protection in different mouse tumor models. A dog version of the cancer vaccine based on frameshift antigens was developed and tested in a small safety trial. The results demonstrate that the vaccine is safe and it can induce strong B and T cell immune responses. Further, I built the human exon junction frameshift database which includes all possible frameshift antigens from mis-splicing events in exon junctions, and I develop a method to find potential frameshift antigens from large cancer immunosignature dataset with these databases. In addition, I test the idea of ‘early cancer diagnosis, early treatment’ in a transgenic mouse cancer model. The results show that ii early treatment gives significantly better protection than late treatment and the correct time point for treatment is crucial to give the best clinical benefit. A model for early treatment is developed with these results. Frameshift neo-antigens from microsatellite regions and mis-splicing events are abundant at mRNA level and they are better antigens than neo-antigens from point mutations in the genomic sequences of cancer patients in terms of high immunogenicity, low probability to cause autoimmune diseases and low cost to develop a broadly effective vaccine. This dissertation demonstrates the feasibility of using frameshift antigens for cancer vaccine development. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2018

Made available in DSpace on 2014-06-11T19:22:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-02Bitstream added on 2014-06-13T19:08:38Z : No. of bitstreams: 1 giratto_dt_me_rcla.pdf: 1764427 bytes, checksum: 1b64e9443f58235f6ad350ec38383d9a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Polybia paulista ou popularmente “paulistinha” é uma vespa social da família Vespidae. Possui hábitos urbanos e grande ocorrência no Sudeste do Brasil, especialmente no Estado de São Paulo, onde tem causado muitos acidentes de importância médica. Na composição de seu veneno encontra-se um potente alérgeno, a proteína Antígeno 5 (Ag5) e embora sua função biológica ainda seja desconhecida, este alérgeno é responsável por importantes reações imunológicas cruzadas com o Ag5 do veneno de outros insetos sociais e com outras proteínas de eucariotos. A importância da reatividade cruzada em pacientes alérgicos ao veneno de vespas sociais é inquestionável, pois estas interações têm impacto direto sobre o diagnóstico e a seleção da melhor conduta terapêutica. Os diagnósticos de alergia são baseados na detecção de anticorpos do tipo IgE específico ao veneno por testes cutâneos ou de sangue. No entanto, respostas falso-positivas decorrentes da reatividade cruzada e respostas falso-negativas provenientes da baixa quantidade de IgE detectada, dificultam a interpretação dos resultados. A sequência completa de cDNA (621 pb) do alérgeno Ag5 do veneno da vespa P. paulista, foi clonada e a análise dos nucleotídeos revelou uma similaridade de 99% com a vespa Polybia scutellaris. Anticorpos policlonais foram produzidos contra a fração eletroforética protéica do Ag5 (25 kDA) de P. paulista e analisados imunologicamente por Western blotting. Os resultados demonstraram que os anticorpos reconheceram especificamente o alérgeno Ag5 no veneno bruto de P. paulista bem como, desenvolveram maior reação imunológica cruzada com os alérgenos Ag5 do veneno das vespas do gênero Polybia, embora não se descarte a possibilidade de ocorrência de reação cruzada com venenos de outros insetos sociais... / Polybia paulista, commonly known as paulistinha, is a social wasp of the family Vespidae. This species occurs in urban areas and is frequent in the Southeastern Brazil, especially in the State of São Paulo, where it has been responsible for many accidents of medical significance. A potent allergen, the protein antigen 5 (Ag5), is an important compound of the wasp venom. Although its biological function remains unknown, this component is responsible for substantial cross-immunological reactions with the Ag5 of venoms of other social insects and with eukaryotic proteins. The importance of cross-reactivity in allergic patients to the wasp venoms is unquestionable, because these interactions present a direct impact on the diagnosis and on the selection of the therapeutic treatment. Allergenic diagnoses are based on the detection of IgE specific to the venom via cutaneous or blood tests. However, sometimes they are hampered by false-positive responses as a result of cross-reactivity and false-negative responses that can occur due to the low amount of IgE detected as consequence of the low sensitivity of the test. The fulllength cDNA (621 bp) from the venom allergen Ag5 wasp P. paulista was cloned and nucleotide analysis revealed 99% of similarity with the wasp Polybia scutellaris. Polyclonal antibodies were produced against the electrophoretic protein fraction of Ag5 (25 kDa) of P. paulista and immunologically analyzed by Western blotting. The results showed that the antibodies strongly recognized the allergen Ag5 in the venom of P. paulista and developed higher cross-immune reaction with the same allergen in wasp venoms of the genus Polybia, although the possibility of cross reaction with other insect venoms not tested in this study cannot be excluded. The model carried out for the Ag5 P. paulista revealed the... (Complete abstract click electronic access below)

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Pesquisas cientÃficas buscando a utilizaÃÃo de antÃgenos de Coccidioides posadasii sÃo comuns na literatura especializada, uma vez que, sÃo instrumentos relevantes para diagnÃstico e possÃvel efeito imunoprotetor em humanos. Diante do exposto, foi realizada caracterizaÃÃo bioquÃmica de antÃgeno protÃico oriundo de C. posadasii. busca ativa de casos humanos de coccidioidomicose no Estado do CearÃ, bem como, avaliaÃÃo da resposta imunolÃgica in vivo. Para concretizar tais objetivos, a caracterizaÃÃo bioquÃmica do antÃgeno foi realizada por meio de eletroforese (SDS-PAGE e 2D-PAGE), detecÃÃo de proteases, glicoproteÃnas e sequenciamento N-terminal e foram buscados, ativamente, quadros de coccidiodiomicose em trÃs caÃadores de tatu com a respectiva descriÃÃo clÃnica e avaliaÃÃo laboratorial. Ademais, foi descrito modelo murino de coccidioidomicose com testagem de possÃvel efeito imunoprotetor do antÃgeno in-house. Quanto a anÃlise bioquÃmica, observou-se delimitaÃÃo de bandas nas faixas de 45-67 kDa e 67-97 kDa (SDS-PAGE), detecÃÃo de glicoproteÃnas, proteases e sequenciamento N-terminal demonstrando serem as bandas uma β-glucosidase e uma glutamina sintetase. Nos casos clÃnicos, foram encontrados queixas pneumÃnicas, exame micolÃgico direto, cultivo de escarro, imunodifusÃo radial dupla (com antÃgeno in-house) e PCR positivos para C. posadasii. No modelo murino, o grupo infectado, na presenÃa de antÃgeno e adjuvante, apresentou, na anÃlise histopatolÃgica, menores alteraÃÃes pulmonares que os demais grupos, alÃm de maior estÃmulo linfÃide esplÃnico. No que concerne a dosagem de citocinas (IL-6, IL-12 e TNFα), nÃo se observou diferenÃa significativa entre os grupos, mas uma tendÃncia à resposta imunoprotetora. O grupo infectado, sem imunoproteÃÃo, apresentou maior perda ponderal. Na anÃlise macroscÃpica, o mÃximo comprometimento foi a presenÃa de 2 granulomas, neste Ãltimo grupo. Na anÃlise dos hemogramas, a sÃrie branca demonstrou maiores diferenÃas entre os grupos. Em conclusÃo, o antÃgeno in-house se mostrou tratar-se de uma β-glicosidase e uma glutamina sintetase que tenderam a estimular a imunidade celular em modelo murino. AlÃm disso, a descriÃÃo de casos humanos contribui para a difusÃo do diagnÃstico precoce da coccidioidomicose e requer investigaÃÃes laboratoriais complementares. / Scientific researches seeking to use Coccidioides posadasii antigens are common in the literature, as relevant instruments to diagnosis and possible immunoprotector effect in humans. Thus, we performed biochemical characterization of protein antigen derived from C. posadasii, an active search for human cases of coccidioidomycosis in CearÃ, as well as evaluation of immune response in vivo. To achieve these goals, the biochemical characterization of the antigen was performed by electrophoresis (SDS-PAGE and 2D-PAGE), detection of proteases, glycoproteins and N-terminal sequencing and we reported three human cases of coccidiodiomycosis in armadillo hunters with its clinical description and laboratory evaluation. Further, a murine model was described testing a possible imunoprotector effect with an in-house antigen. For biochemical analysis, it was observed delimitation bands in ranges 45-67 kDa and 67-97 kDa (SDS-PAGE), detection of glycoproteins, proteases and N-terminal sequencing demonstrating the bands being a β-glucosidase and a glutamine synthetase. In clinical cases, it was found pneumonic disease, direct mycological examination, sputum culture, double radial immunodiffusion (antigen in-house) and PCR positive for C. posadasii. In the murine model, the infected group, in the presence of antigen and adjuvant, showed, histologically, lung disorders smaller than the other groups, and increased splenic lymphoid stimulus. Regarding the cytokines (IL-6, IL-12 and TNF), there was no significant difference between groups, but a trend toward immunoprotective response. The infected group, without immunoprotection, showed greater weight loss. In the macroscopic analysis, the maximum commitment was the presence of 2 granulomas in the latter group. In the analysis of blood counts, the white run showed major differences between groups. In conclusion, the in-house antigen showed that it was a β-glucosidase and a glutamine synthetase which tended to stimulate cellular immunity in a murine model. Moreover, the description of human cases contributes to the spread of early diagnosis of coccidioidomycosis and requires additional laboratory investigations.

In order to further elucidate the interaction between CD23 and β2 integrins (CD11b/CD18) the following objectives were established: Expression and purification of CD11b I-domain as a GST-fusion protein using Escherichia coli; Cloning, synthesis and expression of CD18 I-Like domain.CD11b I-domain has previously been expressed as a GST-fusion protein (Daniels, 2010) and consequently led to comparable expression of CD18 I-like domain as a GST-fusion protein; Preparation of two site-directed mutants of CD18 I-Like domain in order to study the function of the serine residue involved in the S116P mutation. The serine was mutated to proline, as in LAD patients, as well as alanine, a non-polar alternative, in order to contrast and compare binding characteristics.  Expression, refolding and purification of sCD23, and a double mutatedsCD23 (RKΔAA) from E. coli; This was performed according to the method described by Daniels et al. (2005); Investigation of the CD23-CD11b I-like domain interaction through surface plasmon resonance spectroscopy.

Dendritic cells (DCs) are specialized members of the innate immune system that are responsible for the initiation of primary adaptive immune responses whose purpose is to resolve infection and inflammation. During most viral infections, mature dendritic cells present critical viral antigens to naïve T-cells within secondary lymphoid organs, resulting in the generation of an antigen-specific adaptive immune response and clearance of the virus. During infection with HIV-1 however, the virus is not cleared and a chronic systemic infection develops characterized by immune dysfunction, CD4+ T-cell depletion, systemic inflammation, and opportunistic infections. A growing body of evidence indicates that HIV-1 subversion of DCs contributes to both HIV-1 pathologies and viral dissemination. A number of similar effects by accessory HIV-1 peptides on DC physiology have also been reported. In vitro studies demonstrate that HIV-1 inhibits DC maturation and function. Ex vivo studies on the other hand describe partially mature, dysfunctional DCs collecting in secondary lymphoid organs. In vitro studies examining the effects of HIV-1-Tat and HIV-1-Vpr have described opposing effects on DC maturation. Therefore we undertook experiments to comprehensively describe the effects of HIV-1 and the Tat and Vpr accessory peptides on DC maturation and function. To understand the contributions of individual viral proteins to DC dysfunction we infected DCs with a dual tropic HIV-1 and examined phenotypic and functional changes after maturation with inflammatory cytokines. Following this we examined the influence of exogenous and endogenous HIV-1-Tat and HIV-1-Vpr on MDDC maturation and function using recombinant proteins and deletion mutant lab adapted HIV-1 strains. Live dual tropic HIV-1 was found to selectively inhibit aspects of phenotypic maturation as well as antigen capture and presentation functions. MDDC MAPK responsiveness to bacterial LPS remained intact however. Exogenous accessory HIV-1 Tat and Vpr did not affect MDDC phenotype but inhibited dextran endocytosis and viral peptide presentation. HIV-1-gp120 increased iMDDC maturation while blunting cytokine induced decreases in MDDC antigen capture abilities. The deletion of HIV-1-Tat did not affect MDDC phenotype, but was found to affect antigen capture decreases by R5 tropic HIV-1BaL. Deletion of HIV-1-Vpr likewise did not affect MDDC phenotype, however it was found to be influential in HIV-1 induced decreases in MDDC antigen presentation to autologous T-cells. These accumulated results indicate that HIV-1 subverts DC maturation and function through whole virus effects and individual accessory peptide influences. Understanding the mechanisms of DC dysfunction in HIV infection may provide some insight into infection prevention strategies and therapies leading to adaptive immune system activation and viral clearance.

Several cellular and subcellular fractions were prepared from Pseudomonas aeruginosa strain PA-7. Those found to be immunogenic in rabbits included a heat-stable lipopolysaccharide, a protein-lipopolysaccharide complex, a cell wall preparation arid a formalin-killed whole cell vaccine. However, a lipopolysaccharide preparation extracted with phenol and water was found to be a poor immunogen in rabbits. The cell wall fraction proved to be the most effective immunogen in terms of the amount of antibody evoked, and of the duration of the serum antibody response. Hyperimmune sera produced against all four antigens were found to contain a mixed population of 2-mercaptoethanol sensitive and 2-mercaptdethanol resistant antibodies. Gel filtration and ion exchange chromatography studies established the presence of both IgM and IgG immunoglobulins in all four types of hyperimmune serum. Whole immune serum, as well as the IgM and IgG serum fractions, afforded passive protection to mice challenged with twenty or more LD₅₀ of viable organisms. There was an indication that the IgG fraction of two of the four serum types provided better protection than did the IgM fraction, but precipitation studies indicated that this may have been due to greater numbers of IgG immunoglobulins. In addition serum containing a high proportion of 2-mercaptoethanol resistant antibody-was found to promote faster clearance of injected bacteria than did serum taken earlier in the response. Immunodiffusion studies indicated that all four antigenic preparations contained at least one common immunogen; moreover, all serum types were able to react with sheep red blood cells coated with the heat-stable lipopolysaccharide preparation in passive hemagglutination and hemolysin tests. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate