Submitted to: ASM Biodefense Research Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/8/2005
Publication Date: 3/20/2005
Citation: Sundaram, A., Hang, J., Shelton, D.R., Karns, J.S., Zhu, P., Li, S., Amstutz, P., Bull, R., Tang, C. 2005. Sensitive and Rapid Biosensor and Assays for Detection of Bacillus Anthracis Spores. ASM Biodefense Research Meeting, March 20-23, 2005, Baltimore, MD. p.60. Interpretive Summary:
Technical Abstract: Creatv MicroTech is developing a multi-step biosensor for the detection of Bacillus anthracis spores combining immunoassay, culture and real-time PCR. The immunoassay results are reported here. This research covers three areas: antibody evaluation, assay development and instrument development. Antibody affinity and specificity were evaluated using magnetic beads and plating. The instrument technology is based on the Integrating Waveguide Biosensor developed by the Naval Research Laboratory. This biosensor provides a lower limit of detection by reducing background noise, thus improving the signal-to-noise ratio. The instrument was constructed for the use of capillary tubes as the waveguide. Sandwich immunoassays were performed on the inner surface of the capillary tubes using Cy-5 fluorescent dyes. Two immunoassay methods were developed and evaluated. The polyclonal antibody from Naval Medical Research Center (NMRC) had the highest affinity among the antibodies evaluated, but cross-reacted with other Bacillus species. The assay was able to detect <2000 spores. The high affinity of the NMRC antibody was critical for achieving high sensitivity in the multi-step biosensor. A subsequent real-time PCR step will be used to provide specificity, as described in a separate poster entitled 'A Biosensor Platform for Genetic Identification and Quantitation of Bacillus anthracis.' We expect to further increase detection sensitivity by optimizing the assay and using quantum dot fluorescent dyes.