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United States Department of Agriculture

Agricultural Research Service


item Tang, Cha-mei
item Shelton, Daniel
item Zhu, Peixuan
item Hang, Jun
item Li, Shuhong
item Karns, Jeffrey
item Amstutz, Platte

Submitted to: ASM Biodefense Research Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/6/2006
Publication Date: 2/16/2006
Citation: Tang, C., Shelton, D.R., Zhu, P., Hang, J., Li, S., Karns, J.S., Amstutz, P. 2006. Detection of pathogenic agents using the Integrating Waveguide Biosensor. ASM Biodefense Research Meeting, February 15-18, 2006, Baltimore, MD. p.39.

Interpretive Summary:

Technical Abstract: The integrating waveguide biosensor utilizes a sandwich immunoassay for the initial detection of presumptive pathogenic agents. Agents are captured on the inner surface of glass capillary tubes and subsequently detected utilizing a secondary fluor-labeled antibody, with the capillary tubes serving as waveguides for the emitted fluorescence. To date, methods have been developed for the detection of Escherichia coli O157, Salmonella enterica var.Typhimurium and Bacillus anthracis. The sensitivity of the biosensor is approximately 10 cells of E. coli O157 using a Cy5 fluor (or 1 cell using quantum dots) and approximately 100 cells for Salmonella. Utilizing a novel immunoassay technique in which B. anthracis spores are incubated with antibodies prior to capture in capillary tubes, the sensitivity of the biosensor is 2000 spores. Since there is a linear relationship between cell number and fluorescence signal, results are quantitative. The absolute sensitivity of the biosensor is dependent on the volume of sample circulated through the capillary tubes. Research is in progress to optimize the efficiency of cell capture from a flowing sample stream. The biosensor is readily compatible with PCR assays. Since antibodies may lack adequate specificity, the use of PCR for confirmation of presumptive pathogenic agents can be critical. Lysis of captured E. coli O157 cells in capillary tubes, followed by PCR confirmation, has been demonstrated. Capillary tubes can also serve as incubation vessels for the germination/growth of bacterial agents to establish viability, or prior to PCR confirmation. For example, antibodies used for capture of B. anthracis spores also cross-react with many other Bacillus strains. An incubation assay was developed which allows for germination of captured B. anthracis spores within 10 min, followed by PCR confirmation. In conclusion, the biosensor is a versatile platform suitable for detection of a wide variety of food-borne, water-borne, and air-borne pathogenic agents.

Last Modified: 06/25/2017
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