Cell-Surface Antigen Screening via DNA Display Libraries
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Solution Overview
Problem
Traditional methods for screening binding polypeptides, such as antibodies, fail to identify those that can recognize cell-surface antigens in their native conformation due to conformational changes when antigens are solubilized from the plasma membrane.
Innovation Solution
The method involves contacting a variegated nucleic acid-display library of binding polypeptides with cell-surface antigens displayed on cells and isolating library members that specifically bind to the antigens, using techniques like DNA display libraries and deep sequencing to identify polypeptides with novel epitope specificity and functional properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If soluble antigens are used for screening, then the screening process is simple and efficient, but the conformational epitopes are altered resulting in failure to generate binding polypeptides that recognize native antigens
Solution Approach 1:
The patent creates a copy of the native cell surface antigen by displaying it on the exterior surface of a cell, maintaining its native conformational structure. This cellular copy allows binding polypeptides to be screened against the authentic three-dimensional epitopes present on the actual target antigen, resolving the contradiction between screening simplicity and binding specificity.
2Ease of manufacture
If cell surface antigens are solubilized from plasma membrane, then the antigen can be easily handled and screened, but the conformational epitopes are altered
Solution Approach 1:
The cell membrane acts as an intermediary that displays the antigen in its native conformation without requiring solubilization. The cell surface serves as a natural platform that maintains the three-dimensional structure of conformational epitopes while still allowing access for binding polypeptide screening, thus preserving antigen shape while enabling practical handling.
3Device complexity
If traditional soluble antigen screening is used, then the process is straightforward, but binding polypeptides with novel epitope specificity and functional properties cannot be identified
Solution Approach 1:
The patent transitions from two-dimensional soluble antigen screening to three-dimensional cell surface display, adding the spatial dimension of native membrane embedding. This dimensional change preserves the complex conformational epitopes that only exist in the context of the membrane environment, enabling identification of binding polypeptides with novel epitope specificity and functional properties.
Data Source
AI summary
Provided are methods and compositions for identifying binding polypeptides (e.g., antibodies or antigen binding fragments thereof) that specifically binds to a cell-surface antigen. The methods of the invention generally comprise contacting a variegated nucleic acid-display library of binding polypeptides with a cell-surface antigen displayed on the exterior surface of a cell; and isolating from the library at least one library member that specifically binds to the cell-surface antigen on the exterior surface of the cell. Also provided are novel nucleic acid display libraries (e.g., DNA display libraries) useful in the methods of the invention.