Flow cytometric immunoassay using E. coli with autodisplayed Z-domains

Area of Science:

• Biotechnology
• Immunology
• Analytical Chemistry

Background:

• Autodisplayed Z-domains on Escherichia coli (E. coli) offer a platform for sensitive immunoassays.
• Flow cytometry provides high-throughput analysis capabilities for biological samples.

Purpose of the Study:

• To develop and validate a flow cytometry-based immunoassay for simultaneous detection of multiple analytes using E. coli with autodisplayed Z-domains.
• To demonstrate the utility of this method for quantifying clinically relevant biomarkers.

Main Methods:

• Engineered E. coli cells were doubly transfected to express a fluorescent protein (tdTomato) and autodisplayed Z-domains on the outer membrane.
• Simultaneous immunoassay of multiple analytes was performed on the same sample using the engineered E. coli.
• Flow cytometry was employed to detect fluorescence signals from tdTomato and fluorescently labeled antibodies for analyte quantification.

Main Results:

• The engineered E. coli system successfully enabled simultaneous immunoassay of multiple analytes.
• Human hepatitis B virus surface antigen (HBsAg) and C-reactive protein (CRP) were accurately quantified as model analytes.
• The flow cytometry approach allowed for distinct identification and quantification of bound analytes.

Conclusions:

• E. coli cells with autodisplayed Z-domains are effective for flow cytometry-based simultaneous multi-analyte immunoassays.
• This method offers a sensitive and versatile platform for biomarker detection and diagnostics.
• The developed immunoassay demonstrates potential for clinical applications requiring multiplexed biomarker analysis.