Inactivated Cry-Expressing Bacteria for Oral Anthelmintic Delivery
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Solution Overview
Problem
Conventional chemotherapy for soil-transmitted helminth infections lacks full efficacy due to drug resistance, is costly, and poses challenges in delivery to the gastrointestinal tract, especially in resource-limited settings, where existing anthelmintics like benzimidazoles and nicotinic acetylcholine receptor agonists are ineffective against most human parasites.
Innovation Solution
Development of a non-sporulating bacterium, such as a sporulation-defective variant of Bacillus thuringiensis, that expresses a nematicidal protein like Cry5B in its cytosol, which is inactivated or killed to ensure safety and efficacy, allowing oral delivery without sporulation-related toxicity, and is encapsulated for stability and ease of administration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemotherapy drugs (benzimidazoles or nAChR agonists) are used to treat STH infections, then treatment can be administered, but efficacy is insufficient and drug resistance is increasing
Solution Approach 1:
The patent employs a non-sporulating bacterium as a disposable delivery vehicle that expresses nematicidal protein. The bacterium is inactivated after delivering its payload, ensuring safety while maintaining efficacy. This approach replaces conventional chemicals with a biological system that can be safely disposed of after single use, avoiding the development of resistance through selective pressure.
Solution Approach 2:
The patent modifies the bacterium by deleting the sporulation gene (spo0A), changing its life cycle parameters to prevent spore formation. This parameter change eliminates the harmful sporulation-related toxicity while preserving the ability to express and deliver nematicidal protein, thereby improving safety profile without sacrificing efficacy.
2Reliability
If Bacillus thuringiensis is used to express nematicidal protein, then high efficacy is achieved, but sporulation-related toxicity and safety concerns arise
Solution Approach 1:
The patent extracts the harmful sporulation capability from the Bacillus thuringiensis system by deleting the spo0A gene. This removes the source of toxicity while preserving the essential function of nematicidal protein expression and delivery, achieving a separation between beneficial and harmful properties.
Solution Approach 2:
The patent applies local quality modification by creating a strain-specific deletion (spo0A-) that affects only the sporulation pathway while leaving other essential functions (protein expression, cell membrane integrity, nematicidal activity) intact. This localized modification allows the bacterium to be safe for oral administration while maintaining therapeutic efficacy.
3Reliability
If purified nematicidal protein is used for treatment, then efficacy is maintained, but delivery to gastrointestinal tract and cost-effectiveness are compromised
Solution Approach 1:
The patent merges the nematicidal protein with a bacterial delivery system, creating a composite therapeutic agent. This combination allows the protein to be delivered orally in a stable, cost-effective manner, leveraging the bacterium's natural ability to express and secrete proteins while providing protection against degradation in the gastrointestinal tract.
Solution Approach 2:
The bacterium serves itself by expressing the nematicidal protein within its own cellular machinery, eliminating the need for external protein purification and formulation. This self-service approach simplifies production, reduces costs, and maintains protein activity without requiring complex purification processes.
4Productivity
If live Bacillus thuringiensis is administered, then nematicidal protein is expressed, but safety concerns due to potential pathogenicity arise
Solution Approach 1:
The patent applies preliminary inactivation of the bacterium through heat treatment or chemical agents before administration. This preliminary action ensures that the bacterium cannot replicate or cause infection while still allowing it to express and deliver the nematicidal protein, thereby eliminating pathogenicity risks before the therapeutic effect occurs.
Solution Approach 2:
The patent discards the live, potentially pathogenic bacterial cells after they have delivered their nematicidal protein payload. The bacteria are inactivated and discarded, while the functional nematicidal protein is recovered in its activity within the host's gastrointestinal tract to continue exerting its therapeutic effect. This separation eliminates ongoing pathogenicity risks while preserving therapeutic efficacy.
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
The inactivated bacterium effectively treats parasitic worm infections by maintaining anthelmintic activity while ensuring safety and cost-effectiveness, overcoming resistance issues and delivery barriers, with superior efficacy compared to purified proteins.
Implementation Method 1
Cry proteins are non-toxic to vertebrates and are EPA approved for expression in transgenic food... They are also effective against nematodes... Cry5B is effective against three intestinal nematodes
Implementation Method 2
a non-sporulating bacterium, such as a sporulation-defective variant of Bacillus thuringiensis, that expresses a nematicidal protein like Cry5B in its cytosol, which is inactivated or killed to ensure safety and efficacy
Implementation Method 3
sporulation-defective variant of Bacillus thuringiensis... non-sporulating bacterium... genetic mutation that results in a defect in sporulation such that the nematicidal protein is expressed and trapped in the cytosol of the bacterium
Data Source
AI summary
Compositions and methods for treating or reducing the severity or likelihood of occurrence of a parasitic worm or helminth infection in a subject are described. The methods include administering to the subject a therapeutically effective amount of a killed or inactivated recombinant bacterium expressing a crystal protein such as a Bacillus thuringiensis crystal protein (Cry) in the cytosol of the bacterium. The crystal proteins may be full length, truncated, variant, or sub-variant Cry proteins. Examples of crystal proteins include Cry5B, Cry21, Cry14A, Cry6A, and Cry13A. The recombinant bacteria may be treated with an anti-microbial agent before or during administration to a subject.