scFv Antibody Library Design for Reducing Conditions

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current methods for producing recombinant single-chain antibodies, specifically scFvs, face challenges in folding and stability under reducing conditions within cells, limiting their use as intrabodies due to low expression and activity, requiring extensive screening and isolation of clones.

Innovation Solution

Development of a library enriched with scFv clones that can express and bind specifically to target antigens under reducing conditions, utilizing a single optimized framework and introducing diversity in CDR3 loops to enhance stability and expression, allowing for high-level production and purification of functional intrabodies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If scFv is expressed within a cell under reducing conditions, then the scFv can function as an intrabody, but the scFv cannot properly fold and loses binding activity

Engineering Contradiction:

Improvebinding activityVSAvoidfolding stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent modifies the disulfide bridge parameters by replacing cysteine residues with serine or alanine mutations at specific positions (e.g., positions 22 and 92 in the heavy chain variable region, or positions 22 and 88 in the light chain variable region). This parameter change allows the scFv to maintain stability under reducing conditions while preserving binding activity, directly resolving the contradiction between folding stability and binding activity.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a large number of scFv clones are screened to find stable intrabodies, then functional intrabodies can be identified, but the screening process becomes time-consuming and resource-intensive

Engineering Contradiction:

Improveintrabody functionalityVSAvoidscreening time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary engineering of the scFv structure by introducing disulfide bridge-stabilizing mutations during the design phase, before screening. This preliminary action ensures that the scFv clones are pre-optimized for stability under reducing conditions, so that when screening is performed, a much higher proportion of clones are functional, dramatically reducing the time and resources needed to identify usable intrabodies.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If scFv is designed with conserved disulfide bridges for structural stability, then the scFv structure is maintained, but the scFv becomes unstable under reducing cellular conditions

Engineering Contradiction:

Improvestructural stabilityVSAvoidexpression activity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the disulfide bridges by substituting cysteine residues with serine or alanine at critical positions (such as positions 22 and 92 in VH or positions 22 and 88 in VL). This parameter change eliminates the reduction vulnerability while maintaining structural stability through alternative bonding patterns, resolving the contradiction between structural stability and expression activity under reducing conditions.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8841238B2Methods for producing active scFv antibodies and libraries therefor

Publication Date: 2014.09.23 CENT NAT DE LA RECH SCI (C N R S)

AI summary

The present disclosure describes scFv antibody libraries, antibodies isolated from the libraries, and methods of producing and using the same.