Tuberculosis Diagnostic Reagents Using Specific Polypeptides
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Solution Overview
Problem
Current diagnostic tests for tuberculosis in mammals, particularly those using purified protein derivative (PPD) tuberculin, face challenges in differentiating between infected animals and those vaccinated against tuberculosis, leading to compromised specificity and the need for DIVA (Differentiation of Infected and Vaccinated Animals) tests.
Innovation Solution
Development of diagnostic reagents comprising specific polypeptides, such as those with amino acid sequences SEQ ID NO:7 or 8, which elicit a positive response in assays for tuberculosis infection while producing a negative result in vaccinated animals, allowing for differentiation between infected and vaccinated statuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PPD tuberculin is used as diagnostic antigen, then the test can detect tuberculosis infection, but it cannot differentiate between infected and vaccinated animals
Solution Approach 1:
The patent segments the diagnostic approach by using multiple specific antigens (ESAT-6, CFP-10, Rv3615c) instead of a single crude PPD mixture. Each antigen is evaluated independently to determine its ability to differentiate infected from vaccinated animals, allowing selection of the most specific markers for diagnosis.
Solution Approach 2:
The patent extracts specific immunogenic peptides (ESAT-6, CFP-10, Rv3615c) from the crude PPD mixture to create a refined diagnostic reagent. This extraction process removes cross-reactive components that cause false positives in vaccinated animals while retaining the specific antigens that detect true infections.
2Adaptability or versatility
If crude PPD mixture is used, then the test covers broad antigenic coverage, but cross-reactivity with BCG vaccine reduces diagnostic specificity
Solution Approach 1:
The patent extracts specific immunogenic peptides (ESAT-6, CFP-10, Rv3615c) from the crude PPD mixture to create a refined diagnostic reagent. This extraction process removes cross-reactive components that cause false positives in vaccinated animals while retaining the specific antigens that detect true infections.
Solution Approach 2:
The patent applies local quality by focusing on specific regions of the mycobacterial proteome (RD1 deletion region) that possess unique immunogenic properties. Instead of using the entire crude extract, the patent identifies and utilizes only the locally optimal antigenic regions that provide differentiation capability.
Data Source
AI summary
There is provided a diagnostic reagent useful to determine whether an animal has a tuberculosis infection or has been exposed to a tuberculosis agent, for example a Mycobacterium. The reagent is useful to distinguish between such an animal and an animal which has been vaccinated against a tuberculosis infection.