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F. with fully overlapped 15mers (1 residue shift). Screening of these slides with antibodies purified from infected patients and healthy donors shown both a high technical reproducibility as well as epitope mapping regularity when compared with earlier low-throughput systems. Using a traditional transmission threshold to classify positive (reactive) peptides we recognized 2,031 disease-specific peptides and 97 novel parasite antigens, efficiently doubling the number of known antigens and providing a 10-collapse increase in the number of good mapped antigenic determinants for this disease. Finally, further analysis of the chip data showed that optimizing the amount of sequence overlap of displayed peptides can increase the protein space covered in one chip by at least threefold without sacrificing sensitivity. In conclusion, we show the power of high-density peptide chips for the finding of pathogen-specific linear B-cell epitopes from medical samples, thus establishing the stage for high-throughput biomarker finding screenings and proteome-wide studies of immune reactions against pathogens. Detailed knowledge of antigens and epitopes identified in the context of naturally acquired human infections offers important implications for our understanding of immune system reactions against pathogens, and of the immunopathogenesis of infectious diseases. This knowledge 3,4-Dihydroxybenzaldehyde is also important for practical clinical applications such as the development of improved vaccines, treatment strategies, and diagnostics. In the last decades, significant progress has been made in the finding of antigens and epitopes thanks to a number of methodologies such as cDNA manifestation libraries (1), combinatorial peptide libraries (2), and peptide and protein microarrays (3, 4). However, current knowledge of the B-cell antigens and the epitope repertoire identified by the immune system in human infections is still scarce. Indeed, the Immune Epitope Database (5) currently consists of an average of only 10 antigens with mapped B-cell epitopes identified from naturally acquired human infections for bacterial or eukaryotic pathogens. The reasons for this are numerous, but can be mainly attributed to different limitations in the described testing systems. Heterologous MAPK3 manifestation of cDNA libraries has been used to guide antigen finding, but mapping of epitopes most often lags behind as it is definitely a much more expensive exercise. Similarly, combinatorial peptide libraries greatly facilitate the recognition of peptides that are specifically identified by antibodies, but these peptides have sequences that can greatly differ from those of the native epitopes (they may be mimotopes), therefore making it hard to identify the original 3,4-Dihydroxybenzaldehyde antigens. As a result, we currently have only limited detailed info within the good specificities of the antibody response against complex pathogens. The number of tools for studying immune reactions has recently expanded with the inclusion of peptide and protein microarrays, which have been used to identify pathogen-specific antigens and linear epitopes (6C13). Although whole-protein arrays can successfully determine antigens identified by antibodies, they present the typical difficulties associated with the production of recombinant proteins in heterologous or systems, do not provide information on the nature and precise location of the epitope(s) inside a protein, and are more likely to suffer from nonspecific antibody binding because of the exposure of a large number of potentially antigenic regions. In contrast, peptide arrays can provide exquisite fine detail of epitope localization, but until now experienced additional 3,4-Dihydroxybenzaldehyde limitations mostly associated with their reduced capacity, preventing the total scanning of large numbers of candidate proteins. Recent improvements in computerized photolithography and photochemistry have led to the development of a novel high-density peptide microarray technology, where individual peptides can be synthesized on a glass.