Each symbol represents the sensitivity for each pool of 2 rabbits
Each symbol represents the sensitivity for each pool of 2 rabbits. ONO-AE3-208 Western blot). Antibodies raised against peptides worked predominantly in applications where the target ONO-AE3-208 protein was denatured (57% success in Western blot, 66% success in immunohistochemistry), although 37% of the antibodies thus generated did not work in any of these applications. In contrast, antibodies produced by DNA immunization performed well against both denatured and native targets with a high level of success: 93% success in Western blots, 100% success in immunohistochemistry, and 79% success in ELISA. Importantly, success in one assay method was not predictive of success in another. Immunization with full length protein consistently yielded the best results; however, this method is not typically available for new targets, due to the difficulty of generating full length protein. We conclude that DNA immunization strategies which are not encumbered by the limitations of efficacy (peptides) or requirements for full length proteins can be quite successful, particularly when multiple constructs for each protein are used. == Introduction == The post-genomic era has ignited a growing demand for the cost-effective generation of high quality, affinity-purified polyclonal reagents to support the routine detection and/or measurement of numerous protein biomarkers in basic and applied research, and as diagnostic tools. Antibody reagents support traditional immunodetection tools such as immunoblotting, immunohistochemical (IHC) analysis, immunoprecipitation, circulation cytometry, ELISA, as well as more advanced proteomic assay platforms such as planar or bead-based antibody multiplexing microarrays and antibody-oriented mass-spectrometry technologies[1][7]. In designing immunization strategies for these immunodetection methods, the epitope on the target protein that is recognized by the antibody can exist in multiple conformations, ranging from linear, as in a fully denatured protein, to conformationally complex epitopes that are more rigidly structured and often composed of several discontinuous regions, as displayed in folded proteins[8]. The generation NMA of antibody reagents to meet the demands of proteomic applications continues to be driven by standard protein immunization methods[9]. Classical protein immunization strategies most often rely on synthetic peptides[6],[7],[10],[11], large fragment or full-length recombinant proteins of bacterial[9],[12],[13]or mammalian cell origin[6], or purified native proteins[14]as sources of immunogens. By virtue of their low cost, simplicity of synthesis, and historical track-record for polyclonal and monoclonal antibody production the use of peptides as immunogens is usually common[6],[10],[11],[15],[16]. Antibodies raised against peptides represent the majority of antibodies available through antibody catalog vendors. Because very small peptides are poorly immunogenic[14]and large ones are challenging to synthesize, peptide fragments deployed as immunogens typically consist of 12 to 20 amino acid residues[6],[10],[11],[15]. A number of limitations are not usually appreciated constrain the power of peptide immunizations. Among them are difficulties in antigen design based on issues such as lack of effective algorithms for predicting surface regions in the absence of protein structure information or B cell epitopes and[17][19]. Moreover, the conventionally used size of 1220 residues rarely encompasses more than a single epitope and is likely to lack secondary and tertiary conformational structure[9],[10].Consequently, it is much less likely to generate antibodies capable of binding natively folded protein[8]in a sandwich ELISA, although they can work well in many applications against the protein in a denatured form and have widespread proteomic applications. Full length protein antigens address many of the limitations attributed to peptides. Inherently, they contain surface regions, multiple immunogenic epitopes, and are likely to fold to form (at least partially) ONO-AE3-208 native structures even if synthesized in prokaryotic systems[9]. However, recombinant synthesis and/or purification of full length protein antigens can be a daunting task, takes significant time and resources, and is encumbered by uncertainty regarding successful production[20]. More innovative methods such as DNA (or genetic) immunization have emerged as alternative and/or complementary tools to classical antibody generation strategies. DNA ONO-AE3-208 immunization employs an expression plasmid encoding the selected antigen to immunize animals. The transfected tissues of the immunized animal express the antigen which subsequently drives an antibody response[21][25]. DNA immunization with sequences coding polypeptide protein regions combines the advantages of both full length protein and peptide and immunization methods, providing immunogens that comprise relatively large regions of the target protein with the potential for multiple epitopes, faster turn-around, and greater accessibility than full-length protein..