Epitope Polypeptide Skin Test Reagent for Mycobacterial Differentiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current diagnostic tests for mycobacterial infections, such as those caused by Mycobacterium tuberculosis and M. bovis, face challenges in differentiating between infected and vaccinated animals, particularly due to cross-reactivity with the BCG vaccine strain, and existing skin tests require adjuvants that can lead to sensitization and reduced effectiveness over time.
Innovation Solution
A sterile injectable skin test reagent comprising specific epitope polypeptides like CFP-10, ESAT-6, and Rv3615c, without adjuvants, which elicit a positive response in infected animals while distinguishing between infected and vaccinated individuals, using a combination of amino acid sequences that provide accurate and sensitive results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PPD-based skin tests are used for detection of mycobacterial infections, then the test can detect infected animals, but the test cannot differentiate between vaccinated and infected animals due to cross-reactivity with BCG vaccine strain
Solution Approach 1:
The patent extracts specific epitope polypeptides (CFP-10, ESAT-6, Rv3615c) from the crude PPD mixture. These epitopes are derived from genomic regions (RD1) that are deleted in the BCG vaccine strain but present in virulent M. bovis. By using only these specific epitopes rather than the entire PPD mixture, the test achieves the ability to differentiate between vaccinated and infected animals while maintaining detection capability.
2Measurement precision
If adjuvants are added to skin test reagents to enhance immune response, then the test sensitivity is improved, but the reagent causes sensitization that reduces effectiveness over time
Solution Approach 1:
The patent employs a single-use, adjuvant-free formulation of epitope polypeptides. The reagent is designed to be administered once without requiring adjuvants, avoiding the sensitization problem that would reduce effectiveness upon repeated use. The epitopes themselves are sufficient to elicit a detectable immune response in infected animals without causing the harmful sensitization associated with adjuvants.
3Ease of manufacture
If crude PPD mixture is used as diagnostic antigen, then the test can be manufactured easily, but the test lacks specificity due to cross-reactive antigens shared by pathogenic and vaccine strains
Solution Approach 1:
The patent segments the crude PPD mixture into individual epitope polypeptides (CFP-10, ESAT-6, Rv3615c). Each epitope is a distinct molecular entity that can be separately produced and characterized. This segmentation allows for precise control over which antigens are present in the diagnostic reagent, eliminating cross-reactive antigens while maintaining the ability to detect infection through the presence of infection-specific epitopes.
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
There is provided a skin test diagnostic reagent comprising at least one CFP-10 epitope polypeptide, at least one ESAT-6 epitope polypeptide and at least one Rv3615cepitope polypeptide, the reagent eliciting a positive result when administered in a skin test to an animal infected with Mycobacterium bovis or Mycobacterium tuberculosis. The reagent is useful in that it can be used in a method to determine whether an animal is infected with Mycobacterium bovis or Mycobacterium tuberculosis.