A Casadevall

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..Cell wall pigmentation in W. dermatitidis depends on the WdPKS1 gene, which encodes a polyketide synthase required for generating the key precursor for dihydroxynaphthalene melanin biosynthesis...

..anthracis but subsequent studies have questioned its relevance in pathogenesis. In this study, we examined the immunogenicity of recombinant anthrolysin O (rALO) in mice...

..In this study we extended studies of C. neoformans-macrophage cellular interaction/s to human peripheral blood monocytes...

..In this report we have used time-lapse imaging to determine if this occurs with Cn...

..Although often viewed as a specialized adaptation, the capacity for intracellular survival may be widespread among microbes, thus questioning whether the intracellular lifestyle warrants a category of special distinctiveness...

..This article proposes a biological defense initiative based on developing, producing, and stockpiling specific antibody reagents that can be used to protect the population against biological warfare threats...

..Observations with C. neoformans have stimulated a reappraisal of the role of humoral immunity for other pathogens and highlighted the limitations in current methods of assessing the role of Ab in host defense...

..Changes associated with cellular aging in chronic infections could contribute to the remarkable capacity of this fungus to persist in tissues by generating phenotypically and antigenically different capsules...

..Nevertheless, the advantages inherent in the therapeutic and prophylactic use of AMI provide a powerful rationale for continued development that will undoubtedly yield many new vaccines and therapeutic Abs...

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..The description of a vaccine that could protect against various fungal pathogens opens exciting new dimensions in the search for approaches to control fungal diseases...

..Hence, a vaccine against cryptococcosis in humans is probably feasible but there are significant obstacles to vaccine development that range from uncertainties about the pathogenesis of infection to economic considerations...

..Awareness of the weapon potential of human pathogenic fungi is an important consideration for greater preparedness against the threat posed by biowarfare and bioterrorism...

..The discovery of vesicular transport in fungi opens many new avenues for investigation in basic cell biology and pathogenesis...

..Protective monoclonal antibodies can be used to identify antigens that induce useful humoral responses...

..To address this impediment to studies of host-microorganism interactions, we propose a new theoretical approach to understanding microbial pathogenesis, known as the 'damage-response' framework...

..The potential of antibodies as antiinfective agents has not been fully tapped. Antibody-based therapies constitute a potentially useful option against newly emergent pathogens...

..This approach was recently shown to target and eliminate HIV-1-infected cells in vitro and in mouse models, and provides a new approach for eliminating virally infected cells...

..The challenge now is to identify antigens that elicit protective antibodies, use them in vaccine design and understand how humoral and cellular immune mechanisms cooperate...

..The findings with C. neoformans may provide a paradigm for understanding the origin and maintenance of virulence in other pathogenic environmental fungi...

..The results show that both the variable and constant regions of MAb 18B7 are biologically functional and support the use of this MAb in human therapeutic trials...

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..In fact, this concept appears to work best for certain types of bacterial pathogens, being less well suited for viruses and commensal organisms with pathogenic potential...

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..Furthermore, studies with monoclonal antibodies suggest various explanations for the inability of standard methods to demonstrate the potential efficacy of AMI for certain pathogens...

..Deforestation and proliferation of fungal spores at cretaceous-tertiary boundary suggests that fungal diseases could have contributed to the demise of dinosaurs and the flourishing of mammalian species...

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..Mast cells were observed to occasionally phagocytose C. neoformans in vitro in the presence of IgE MAb. Our observations suggest that eosinophils may be effector cells against C. neoformans...

..Our results provide additional evidence that antibody administration can produce quantitative and qualitative changes in the inflammatory response to a pathogen...

..The importance of this finding is underscored by the increased likelihood of phenotypic switching in chronic cryptococcosis; thus this mechanism may account for the inability to eradicate the organism in immunocompromised hosts...

..01). The treatment did not cause hematological toxicity, as demonstrated by platelet counts. This feasibility study establishes that RIT can be applied to the treatment of bacterial infections...

..neoformans requires both Th1- and Th2-associated cytokines and reveal the complexity of the mechanisms through which antibodies modulate infection with this organism...

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..The results indicate that serum clearance and organ deposition of LAM in mice are affected by the presence of LAM-binding antibody and suggest a mechanism by which antibody could modify the course of mycobacterial infection...

..Furthermore, our observations suggest that C. neoformans occupies a unique niche among the intracellular pathogens whereby survival in phagocytic cells is accompanied by intracellular polysaccharide production...

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..Sequence and Southern blot analysis indicate that the serotype-D CNPS-specific mAbs arose from only a few precursor B cells...

..neoformans; and (iv) reduced antibody responses to cryptococcal polysaccharide. The results show that maintenance of persistent infection is associated with downregulation of both cellular and humoral immune responses...

..Our results imply that there are protective and nonprotective cell-mediated immune responses and highlight the complexity of the immune response to C. neoformans antigens...

..Our observations may have important implications for the design of vaccines, for passive antibody strategies, and provide a previously unexplored system for studying secretory pathways in Gram-positive bacteria...

..Our results indicate that C. neoformans biofilms are susceptible to treatment with antibody-targeted alpha radiation, suggesting a novel option for the prevention or treatment of microbial biofilms on indwelling medical devices...

..Our results support the emerging concept that neutrophils play an important function in modulating the development of the immune response...

..Our findings have implications for the potential contribution of Ab responses to defense against microbial diseases because Ab-mediated immunity may be protective, nonprotective, or even deleterious to the host...

..The high activity of voriconazole against both melanized and nonmelanized cells results suggest that voriconazole may be a particularly valuable drug for cryptococcosis...

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..We conclude that RIT is more effective than amphotericin B against systemic infection with C. neoformans...

..The dependence of isotype efficacy on host genetics underscores a previously unsuspected complex relationship between the cellular and humoral arms of the adaptive immune response...

..Thus, systemic administration of a monoclonal antibody can modify the course of lethal intracerebral C. neoformans infection in mice by prolonging survival and decreasing fungal burden in brain tissues...

..Phenotypic switching may play a role in the ability of this fungus to escape host defenses and establish chronic infections...

..neoformans may result from reduced activity against C. neoformans glucan synthase or from yet undiscovered mechanisms of action operative in other fungal pathogens but not in C. neoformans...

..neoformans delayed melanization of yeast cells in vivo and prolonged average mouse survival. The results suggest that inhibition of melanization in vivo may facilitate control of C. neoformans infection...

..MAbs to melanin reduced the growth rate of in vitro-melanized C. neoformans cells, suggesting a new mechanism of antibody-mediated protection...

..neoformans biofilm formation involved capsular polysaccharide release and adherence. Our results suggest that biofilm formation may diminish the efficacies of some antifungal drugs during cryptococcal infection...

..Furthermore, isotype affected the polyreactivity of V region identical antibodies, implying a role for C region in determining self-reactivity...

..The results suggest that the variability observed in vaccination studies with PA-derived vaccines is a result of host heterogeneity and implies a need to develop other antigens as vaccine candidates...

..These results are consistent with the view that soil amoebae may contribute to the selection and maintenance of certain traits in pathogenic dimorphic fungi that confer on these microbes the capacity for virulence in mammals...

..The results indicate an important role for B cells in host defense against C. neoformans infection and demonstrate a surprising dependence of Ab-mediated protection on B cells in this system...

..Laccase was detected in the fungal cell cytoplasm, cell wall, and capsule in vivo. The amount of laccase found in different sites varied as a function of the time of infection...

..These results identify the first linear neutralizing epitopes of PA and show that peptides containing epitope sequences can elicit neutralizing antibody responses, a finding that could be exploited for vaccine design...

..Furthermore, the results illustrate the first molecular assignment of a C. neoformans polysaccharide epitope and suggest a general strategy for the identification of GXM epitopes...

..Hence, the function of GalXM appears to be more consistent with that of an exopolysaccharide than a structural component of the cryptococcal capsule...

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..Furthermore, the results indicate that fungal melanins protect C. neoformans and H. capsulatum from the activities of amphotericin B and caspofungin and that this protection is not demonstrable by standard broth macrodilution assays...

..neoformans strains being more susceptible, on average, to heat killing. The results suggest a consistent explanation for the geographic differences between serotype A and D strains and for the dermatotropism of serotype D strains...

..The crystals apparently formed because of the interaction of a host protein with the cryptococcal polysaccharide. Crystal formation likely contributes to pathogenesis by causing cellular damage...

..We also found that the plb1 strain exhibited a growth defect in a macrophage-like cell line. These data demonstrate that secretory phospholipase is a virulence factor for C. neoformans...

..Hence, phenotypic switching is an adaptive mechanism linked to virulence that can generate cell types with very different biological characteristics...

..neoformans. This has important implications for immunotherapy and vaccine design that are reinforced by the finding that GXM and peptide reactivities are determined by different amino acid residues...

..The results indicate that the population of C. neoformans cells in tissue is in a highly dynamic state, implying that the immune system must confront cells with varying characteristics during the course of infection...

..The results provide strong evidence that cryptococcal melanization can influence the immune response to infection and suggest that immunomodulation is an additional mechanism by which the pigment contributes to virulence...

..In summary, differences in AM function in rats and mice suggest an explanation for the species differences in susceptibility to C. neoformans based on the inherent efficacy of a central effector cell of the innate immune system...

..Hence, voriconazole affects melanization in C. neoformans by interacting directly with laccase, which may increase the efficacy of this potent antifungal against certain pigmented fungi...

..This observation suggests a potential mechanism for increasing the number of effector cells after microbial ingestion, but can also promote the spread of infection...

..In conclusion, RIT of metastatic melanoma can be effective over a wide range of tumor melanin concentrations. The results can be useful in the design of a clinical trial of melanin-targeting RIT in patients with metastatic melanoma...

..The results imply that the contribution of N-glycan structure to immunoglobulin function varies depending on the Ag-Ab system...

..However, MAb 7.5G slowed the proteolytic digestion of PA by furin in vitro, suggesting a potential mechanism for Ab-mediated protection. These observations indicate that some Abs to domain 1 can contribute to host protection...

..This finding suggests that antibody agglutination effects persist in the phagosome to entangle nascent daughter cells and this phenomenon may contribute to antibody-mediated protection...

..A mechanism for capsule growth is proposed based on the extracellular release and entanglement of GXM molecules...

..These findings highlight a new parameter for evaluating vaccine responses and the possibility of harnessing optimal FcγR interactions in the design of passive immunization strategies...

..Melanin, a high-molecular weight pigment that is ubiquitous in nature, protects melanized microorganisms against high doses of ionizing radiation. However, the physics of melanin interaction with ionizing radiation is unknown...

..anthracis Sterne spores. These results indicate that RIT with MAbs that target B. anthracis toxin components can be used to treat experimental anthrax infection and suggest that toxigenic bacteria may be targeted with radiolabeled MAbs...

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..One MAb and a subset of human antibodies bind AM specifically, suggesting that this polysaccharide is antigenically distinct and is expressed in human infection...

..Thus, these heptapeptides appear to have potentially significant advantages for targeted therapy of melanoma relative to existing melanin-binding peptides...

..Our results provide strong support for the existing classification of two serological types for strains assigned to variety neoformans and indicate qualitative and quantitative antigenic differences among serotype A and D strains...

..These data show that laccase is present as a tightly associated cell wall enzyme that is readily accessible for interactions with host immune cells...

..These findings suggest a mechanism by which C. neoformans infections fail to induce strong inflammatory responses in patients with cryptococcal meningoencephalitis and have important implications for antibody therapy...

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..On a practical level, Dr. Casadevall s laboratory hopes to use this information in design of therapeutic antibodies and vaccines against C. neoformans. ..

..Furthermore, these studies will provide information that could be used to design vaccines and new therapies based on immunological reagents such as antibodies. ..

..neoformans and also to other efforts to develop Ab therapy, vaccines and fundamental immunology. ..

..neoformans; 3) To determine how GalXM contributes to C. neoformans capsular structure organization and evaluate the efficacy of antibodies to this polysaccharide. ..

..It is anticipated that the work proposed here will provide important insights into the biology of melanin and in doing so highlight novel strategies for antimicrobial drug development. ..

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..These studies are expected to yield new insights on fundamental aspects of antibody function as well as practical information for the development of second generation antibody reagents for human therapy. ..

..discoideum system will lead to the identification of genetic pathways that are not immediately obvious from standard fungal-macrophage experiments. ..

..It is anticipated that the work proposed here will provide important insights into the biology of melanin and in doing so highlight novel strategies for antimicrobial drug development. ..

..In this regard, a monoclonal antibody to fungal melanin made as part of this research program is already in clinical evaluation for the therapy of melanoma. ..

..By comparing the immune response in Ab-permissive and Ab-non-permissive murine strains we will learn the conditions and mechanisms by which Ab-mediates protection against C. neoformans. ..

..To establish the most effective and least toxic human constant region against C. neoformans in mice; and Aim 3. To determine the consequences of antibody-mediated deposition of cryptococcal polysaccharide in reticuloendothelial cells. ..

..To determine the effect of polysaccharide-protein conjugate vaccination on pulmonary defenses against C. neoformans in the context of cytokine- and nitric oxide-related mechanisms. ..