Codon-optimized Bacillus anthracis protective antigen for vaccine
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Solution Overview
Problem
Current anthrax vaccines, particularly the licensed human vaccine BioThrax, face challenges with batch-to-batch variability and inconsistency in efficacy due to their nature as filtered extracts from Bacillus anthracis, and DNA vaccines often fail to elicit robust humoral responses in humans, which are critical for surviving anthrax infection.
Innovation Solution
A codon-optimized DNA construct of the Bacillus anthracis protective antigen (PA) is developed, utilizing rare host codons to ensure efficient translation and correct folding of the protein in mammalian cells, thereby enhancing immunogenicity and mimicking the native PA protein structure, which is incorporated into DNA expression systems for improved vaccine efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If all bacterial codons are replaced with the most highly used codons in the mammalian host cell, then translation efficiency is improved, but correct protein folding is compromised
Solution Approach 1:
The patent applies local quality by differentiating codon optimization strategies across different regions of the gene. Highly utilized mammalian codons are used in regions requiring efficient translation, while rare codons are strategically retained in specific regions to induce ribosomal stalling that facilitates correct protein folding. This localized approach allows simultaneous optimization of both translation efficiency and folding accuracy in different gene segments.
Solution Approach 2:
The patent implements partial codon optimization rather than complete optimization throughout the entire gene sequence. By selectively optimizing only certain regions while leaving others with rare codons, the invention achieves sufficient translation efficiency without completely eliminating the ribosomal stalling events necessary for proper protein folding. This partial action resolves the contradiction between full optimization and folding accuracy.
2Manufacturing precision
If rare codons are used in the DNA construct, then correct protein folding is maintained, but translation efficiency decreases
Solution Approach 1:
The patent strategically distributes rare codons only in specific regions where ribosomal stalling is beneficial for protein folding, rather than uniformly throughout the sequence. This localized use of rare codons minimizes their negative impact on overall translation efficiency while preserving their positive effect on folding accuracy in critical regions.
Solution Approach 2:
The patent modifies codon usage parameters selectively across different gene regions. By changing codon frequency parameters locally rather than globally, the invention maintains translation efficiency at acceptable levels while introducing rare codons only where needed to induce folding-appropriate ribosomal pausing events.
3Ease of manufacture
If the vaccine is made as a filtered extract from B. anthracis, then production is simplified, but batch-to-batch variability and inconsistency in efficacy occur
Solution Approach 1:
The patent creates a synthetic copy of the protective antigen gene with optimized codon usage for mammalian expression systems. This synthetic gene copy is inserted into DNA expression vectors that can be propagated in bacterial hosts, producing a consistent, defined product. This copying approach replaces the variable filtered extract with a reproducible genetic construct, eliminating batch-to-batch variability while maintaining production feasibility.
Solution Approach 2:
The patent performs preliminary codon optimization of the protective antigen gene sequence before expression in mammalian systems. By pre-modifying the gene sequence to match mammalian codon usage patterns in critical regions, the invention ensures consistent and efficient expression of the antigen, thereby producing reliable vaccine batches with consistent efficacy without requiring complex purification processes.
Data Source
AI summary
The invention relates to a humanized nucleic acid construct from Bacillus anthracis protective antigen (PA) gene and method of modifying the gene. The humanized gene, and method of producing it, improves the structural fidelity of expressed protein product, when produced in mammalian host cells, to native, bacterially produced protein. The construct is useful in nucleic acid based vaccine formulations against B. anthracis.