AcfD Protein Fragments for E. coli Vaccine Solubility
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Solution Overview
Problem
Current vaccines against extraintestinal pathogenic Escherichia coli (ExPEC) strains and intestinal pathotypes like EAEC, EIEC, EPEC, and ETEC are limited in their antigenic coverage and immunogenic efficacy, particularly in providing broad protection against these pathogens.
Innovation Solution
Development of variants of the accessory colonization factor D (AcfD) precursor protein, including fragments with increased solubility and conservative amino acid substitutions, which induce a substantially similar immune response as the full-length protein, for use in immunization against pathogenic E. coli strains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If full-length AcfD protein is used as vaccine antigen, then broad antigenic coverage is achieved, but solubility and immunogenic efficacy are limited
Solution Approach 1:
The full-length AcfD protein is divided into multiple fragments (e.g., N-terminal fragment, C-terminal fragment, internal fragments) that can be used individually or in combination. These fragments retain immunogenicity while improving solubility and reducing aggregation, thereby resolving the contradiction between broad coverage and effective immunogenicity.
Solution Approach 2:
Specific regions of the AcfD protein are identified and optimized for enhanced solubility and immunogenicity. Mutations are introduced at specific locations (e.g., adding solubility-enhancing tags, modifying hydrophobic regions) to improve local properties without compromising overall antigenic coverage.
2Adaptability or versatility
If full-length AcfD protein is used, then complete antigenic structure is presented, but solubility is reduced leading to poor vaccine performance
Solution Approach 1:
The amino acid sequence of AcfD is modified through various parameters including adding solubility-enhancing tags (e.g., His-tag, GST-tag), introducing point mutations to reduce aggregation-prone regions, and optimizing expression conditions. These parameter changes improve solubility while maintaining antigenic integrity.
Solution Approach 2:
Solubility-enhancing tags and fusion proteins are used as intermediaries to improve the solubility of AcfD during production. These intermediaries facilitate proper folding and solubility without compromising the immunogenic epitopes, and can be removed or retained depending on the vaccine formulation.
Data Source
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AI summary
Variants of the pathogenic E. coli 'AcfD precursor' have been identified with increased solubility as compared to the native AcfD protein that raise a substantially similar immune response in a subject as the native AcfD protein.