Mutated E. coli LT Subunit A for Reduced Toxicity Adjuvant
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Solution Overview
Problem
The high toxicity of wild-type heat-labile enterotoxin (LT) produced by Enterotoxigenic Escherichia coli limits its clinical use, despite its ability to function as a mucosal adjuvant and induce immune responses, necessitating the development of mutated forms with reduced toxicity while maintaining immunogenicity.
Innovation Solution
A mutated LTA with an amino acid substitution at position 61, such as D, E, H, I, K, L, N, P, Q, R, Y, or W, is used to create a detoxified LT with reduced toxicity, which is then used in vaccines either alone or combined with LT subunit B, and the corresponding nucleic acid sequences are encoded and expressed for production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type LT is used as a mucosal adjuvant to induce immune responses, then immunogenicity is improved, but toxicity increases
Solution Approach 1:
The patent applies parameter changes by substituting specific amino acid residues in the LTA subunit of LT (positions 61, 236, or 238) to alter the toxin's biological activity. These point mutations reduce the enzymatic activity of the A1 peptide while preserving its ability to bind NAD and interact with Gsα, thereby reducing toxicity while maintaining immunogenicity. The substituted residues (Asn, Gln, Lys, Arg, Thr, Ser, Ala, Val, Met, Ile, Leu, Phe, Tyr, Trp, His, Asp, or Glu) modify the structural conformation or catalytic efficiency of the toxin without completely abolishing its function.
2Object-affected harmful factors
If LT is detoxified through mutation to reduce toxicity, then safety is improved, but immunogenicity may be reduced
Solution Approach 1:
The patent applies local quality by making targeted point mutations at specific positions (61, 236, or 238) within the LTA subunit rather than globally altering the entire protein structure. These localized changes affect only the catalytic activity of the A1 peptide while leaving other regions of the toxin intact. The B subunit pentamer and other functional domains remain unchanged, preserving the toxin's ability to bind GM1 receptors, facilitate membrane insertion, and elicit immune responses.
Data Source
AI summary
This invention relates to a mutant E. coli heat-labile enterotoxin (LT) subunit A that can be used as an adjuvant. This subunit A mutant contains an amino acid substitution at a position corresponding to position 61 of a wild-type LT. An LT containing this mutated subunit A exhibits reduced toxicity compared to its wild type counterpart.