Mutant Streptolysin O Proteins for Vaccine Safety
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Solution Overview
Problem
Streptolysin O (SLO) proteins, crucial for vaccine development against Streptococcus pyogenes, pose significant toxic side effects due to their hemolytic activity, hindering their use as effective vaccine candidates.
Innovation Solution
Development of mutant SLO proteins with reduced hemolytic activity, specifically at positions P427 and W535, which maintain immunogenicity and confer protection against S. pyogenes while minimizing toxicity, incorporated into vaccine compositions and nucleic acid molecules for recombinant production and purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type SLO proteins are used as vaccine candidates, then strong immune response is induced, but toxic side effects occur due to hemolytic activity
Solution Approach 1:
The patent applies parameter changes by modifying specific amino acid residues in the SLO protein sequence (e.g., substitutions at positions 427, 530, 535, 482) to alter the protein's hemolytic properties while preserving its immunogenicity. This direct modification of molecular parameters resolves the contradiction by creating variants with reduced toxicity that maintain vaccine effectiveness.
Solution Approach 2:
The patent applies local quality by making targeted modifications at specific locations (amino acid positions) within the SLO protein structure rather than altering the entire molecule. This allows the vaccine to maintain strong immune response properties in most regions while having reduced hemolytic activity at specific critical sites, thus resolving the contradiction between immunogenicity and toxicity.
2Object-affected harmful factors
If mutant SLO proteins with reduced hemolytic activity are developed, then safety is improved, but immunogenicity may be compromised
Solution Approach 1:
The patent systematically tests multiple parameter variations (different amino acid substitutions at various positions) to identify combinations that reduce hemolytic activity below 50% of wild-type while maintaining sufficient immunogenicity. This approach resolves the contradiction by finding optimal parameter settings that balance safety and efficacy.
Solution Approach 2:
The patent reduces hemolytic activity to a partial level (retaining some activity below 50% of wild-type) rather than completely eliminating it, which appears to be sufficient for safety while preserving the protein's ability to induce protective immune responses. This partial reduction resolves the contradiction without completely sacrificing immunogenicity.
3Object-affected harmful factors
If multiple amino acid substitutions are introduced to reduce toxicity, then hemolytic activity decreases, but protein complexity increases
Solution Approach 1:
The patent focuses modifications on specific local regions (key amino acid positions such as 427, 482, 530, 535) rather than distributing changes throughout the entire protein structure. This localized approach reduces hemolytic activity through targeted substitutions while minimizing overall protein complexity and maintaining structural integrity for immunogenicity.
Solution Approach 2:
The patent evaluates multiple parameter combinations (different amino acid substitutions at specific positions) to identify the most effective yet simplest variants. By systematically testing and selecting optimal parameter sets, the patent resolves the contradiction by finding substitutions that achieve sufficient toxicity reduction with minimal complexity increase.
Data Source
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AI summary
Forms of GAS25 (streptolysin O) which are not toxic but which still maintain the ability to induce protection against S. pyogenes are useful in vaccine compositions to induce protection against S. pyogenes.