Detoxified E. coli AcfD Immunogens for Vaccine Safety
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Solution Overview
Problem
Current vaccines against extraintestinal pathogenic Escherichia coli (ExPEC) strains, particularly intestinal pathotypes like EAEC, EIEC, EPEC, and ETEC, face challenges in terms of toxicity, solubility, and immune response efficacy, limiting their effectiveness in immunization.
Innovation Solution
Development of detoxified and solubilized variants of the AcfD (orf3526) protein, including mutations and deletions that reduce toxicity and enhance solubility while maintaining a similar immune response to the full-length protein, for use in immunization against E. coli infections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-length AcfD protein is used as immunogen, then immune response is elicited, but toxicity increases and solubility decreases
Solution Approach 1:
The full-length AcfD protein is divided into smaller fragments (e.g., amino acids 1-200, 201-400, 401-600, 601-800, 801-1000) that retain immunogenicity while eliminating toxic regions. This segmentation allows the vaccine to stimulate immune response without the harmful effects of the complete toxin structure.
Solution Approach 2:
Toxic domains are extracted and removed from the AcfD protein sequence, retaining only the immunogenic epitopes. This extraction process creates a detoxified version that preserves protective immunity while removing pathogenic properties.
2Reliability
If full-length AcfD protein is used as immunogen, then immune response is elicited, but expression and purification difficulty increases
Solution Approach 1:
Dividing the full-length protein into smaller fragments improves expression yields and simplifies purification processes. The smaller size reduces aggregation and inclusion body formation, making recombinant production more efficient and cost-effective.
3Object-affected harmful factors
If detoxified variants are used, then toxicity is reduced, but immune response may be weakened
Solution Approach 1:
Specific regions of the AcfD protein are modified to remove toxicity while preserving local immunogenic epitopes. The detoxified variants maintain critical antigenic determinants in key locations, ensuring immune recognition and protective response are preserved.
Solution Approach 2:
Amino acid substitutions and deletions are strategically introduced to alter protein properties, reducing toxicity while maintaining or enhancing immunogenicity. These parameter changes create variants with improved safety profiles and comparable or superior immune responses.
Data Source
AI summary
Detoxified variants of the pathogenic E. coli ‘AcfD precursor’ (orf3526) have been identified that raise a substantially similar immune response in a subject as the native AcfD (orB526) protein. The detoxified variants may be further modified to have increased solubility as compared to the native AcfD (orf3526) protein.