Glycoconjugate Based Diagnostics for Bacterial Toxins

The Biothreat toxins include the most lethal agents ever described. Nanogram amounts of aerosolized or injected toxins cause death. To prevent loss of life, detection of biothreat toxin must be made rapidly, accurately and with exquisite sensitivity. In addition, an ideal diagnostic should be stable and simple enough for individuals with limited medical training, such as first responders (police and fire-fighters) to use on site. Current 'gold standard' detection assays are time consuming and sample dependent, and fall far short of the ideal. <P>Our preliminary studies have shown that glycoconjugate ligands mimicking the natural toxin receptor can be used for rapid and precise detection of closely related toxins. As proof of principle, we have developed tailored carbohydrates that can discriminate between the two antigenic forms of Shiga toxin, Stx1 and Stx2. We propose to extend these studies to develop diagnostic and therapeutic products.<P> In Aim 1, we will develop 2nd and 3rd generation toxin ligands specific for Shiga, Ricin, Botulinum, Clostridium perfingens epsilon toxins and Staphylococcus enterotoxin B (SEB). These ligands will maximize cooperative binding and optimize differentiation between variants in each toxin class. <P>In Aim 2 we will develop and evaluate different diagnostic platforms. Biotin will be covalently linked to the ligands. Conjugation to prefabricated streptavidin coated microtiter plates yields a glycoconjugate microarray cartridge, ideal for rapid testing of toxins in a point-of-care setting. <P>In Aim 3, we will validate and perform pre-clinical evaluation of lead compounds from Aim 1. We will quantify the effectiveness of the microarray diagnostics and their potential as therapeutics in tissue culture, in mouse models, and in human specimens ex vivo. Sensitivity, specificity, rapidity, ruggedness, ease-of-use and cost-effectiveness will be evaluated to establish proof of principle.