Dual Fluorescent Antibody Assay for Bacillus anthracis Detection
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Solution Overview
Problem
Current methods for detecting Bacillus anthracis require separate culture conditions and vials for each antigen, increasing time and cost, and are prone to misinterpretation due to the inhibition of anti-Gal-NAG-PS monoclonal antibodies by the capsule, making it difficult to simultaneously detect cell wall and capsule antigens.
Innovation Solution
The use of detectably labeled antibody Fab fragments specific for the cell wall antigen in tandem with differentially labeled anti-capsule antibodies allows for simultaneous detection of both antigens in a single sample, eliminating the need for multiple culture conditions and reducing misinterpretation by using contrasting fluorophores to visualize the presence of both antigens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate culture conditions and vials are used for each antigen, then each antigen can be detected accurately, but the time and cost to complete the assay increases
Solution Approach 1:
The patent combines detection of two separate antigens (cell wall Gal-NAG-PS and capsule poly-D-glutamic acid) into a single vial and single incubation procedure. The Fab fragment antibody for cell wall antigen and intact IgM antibody for capsule antigen are mixed together and applied to the same bacterial sample simultaneously, eliminating the need for separate culture conditions and multiple vials while maintaining detection accuracy for both antigens.
Solution Approach 2:
The patent segments the antibody into Fab fragments for the cell wall antigen detection, which are smaller in size and can penetrate the capsule structure. This segmentation allows the Fab fragments to access the cell wall antigen even when the capsule is present, enabling simultaneous detection of both antigens in the same sample without requiring separate culture conditions.
2Measurement precision
If intact IgM antibodies are used for cell wall detection, then the antibody binds to the antigen, but the capsule prevents penetration and detection
Solution Approach 1:
The patent segments the intact IgM antibody into Fab fragments, which are smaller in molecular size and can penetrate through the capsule structure. The Fab fragments retain the antigen-binding capability while their reduced size allows them to access the cell wall antigen even when the capsule is present, overcoming the penetration barrier that prevents intact antibodies from binding.
Solution Approach 2:
The patent changes the size parameter of the antibody molecule by using Fab fragments instead of intact IgM. This parameter change (reducing molecular size) allows the antibody to penetrate the capsule structure and reach the cell wall antigen, transforming the harmful effect of capsule inhibition into a successful detection outcome.
3Measurement precision
If multiple culture conditions are used, then both antigens can be detected, but the complexity and cost of the assay increases
Solution Approach 1:
The patent merges the detection of both antigens into a single culture condition and single vial. By using Fab fragments that can penetrate the capsule, the assay no longer requires separate culture conditions for capsule formation and cell wall exposure. Both antigens can be detected simultaneously in the same incubation, eliminating the complexity of managing multiple culture conditions.
4Measurement precision
If separate vials are used for each antigen, then detection accuracy is maintained, but misinterpretation of results occurs
Solution Approach 1:
The patent combines both antigen detections in the same vial and same incubation, allowing direct visual comparison of both fluorescent signals. The Fab fragment antibody for cell wall antigen and intact IgM for capsule antigen are applied simultaneously, and their fluorescent signals can be observed together under the microscope, eliminating ambiguity and misinterpretation that occurs when separate vials are used.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables rapid and accurate identification of Bacillus anthracis in a single incubation, improving the speed and accuracy of detection and allowing for the identification of atypical isolates and aberrant Bacillus species, while minimizing the need for further culturing and reducing the risk of misinterpretation.
Implementation Method 1
the addition of detectably labeled antibody Fab fragment specific for a cell wall antigen in tandem with differentially detectably labeled anti-capsule antibody
Implementation Method 2
differentially detectably labeled anti-capsule antibody
Implementation Method 3
Recognized antigens are visible when examined microscopically using a light source which causes the antibody-bound fluorophore to emit a specific wavelength
Data Source
AI summary
In this application is described a method for rapidly and accurately identifying B. anthracis in a sample by simultaneously detecting the presence of cell wall antigen and capsule antigen in the same sample culture grown under capsule inducing conditions. Other uses and advantages of the method of the invention are described herein.