Generation of bivalent aptamers with high affinity and selectivity for detection of viruses and bacteria from environmental samples

Better methodologies for the rapid detection of pathogenic bacteria and viruses are needed. A problem with current antibody-based assays is cross-reactivity with similar, but harmless, species. RMD, Inc., proposes developing nucleic acid-based affinity reagents (aptamers) against the spore coat of the model organism Bacillus thuringiensis. Aptamers displaying fast binding rates (kon) will be selected in order to increase the speed of the assay. A novel approach using bivalent, bispecific aptamers will be utilized to increase the binding affinities to at least equal that of typical antibodies. The selectivity of the aptamers will be enhanced by employing counterselection procedures whereby aptamers binding related species are deselected. Finally, the aptamers will be applied to an ELISA-like protocol and their performance directly compared to antibodies. Commercial Applications: A more rapid, sensitive, and selective assay for the detection of bacteria and viruses will have widespread applications in homeland security, the military, healthcare, and food safety. The assay could be used to screen ports of entry, public places of interest, military sites and battlefields for evidence of biological threat agents. Likewise, the assay could be used in a clinical setting, in a laboratory or at the point-of-care, to rapidly diagnose infectious diseases.