Single-Chain Antibody Fragments for SARS-CoV-2 Nucleocapsid Detection
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Solution Overview
Problem
Existing SARS-CoV-2 detection methods, particularly those using monoclonal antibodies, are cumbersome, costly, and lack stability, limiting their efficiency and applicability in rapid and sensitive detection.
Innovation Solution
Development of a single-chain antibody fragment (scFv) targeting the SARS-CoV-2 nucleocapsid protein, comprising a heavy chain variable region, linker peptide, and light chain variable region, with a specific amino acid sequence, and a preparation method involving expression, immunization, and phage display to enhance specificity and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If monoclonal antibodies are used for SARS-CoV-2 detection, then detection sensitivity is improved, but preparation cycle is extended and cost increases
Solution Approach 1:
The patent extracts only the essential variable regions (VH and VL) from complete monoclonal antibodies to create single-chain antibody fragments (scFv). This extraction maintains the core antigen-binding function while eliminating the time-consuming hybridoma production process, achieving rapid preparation within days rather than weeks or months while preserving detection sensitivity
Solution Approach 2:
The patent employs scFv fragments that can be produced recombinantly in E. coli, replacing expensive and time-intensive monoclonal antibody production. The scFv fragments are cost-effective, easily modifiable, and can be rapidly produced through bacterial expression systems, significantly reducing both preparation time and cost while maintaining functional efficacy
2Measurement precision
If monoclonal antibodies are used for SARS-CoV-2 detection, then detection specificity is improved, but batch stability deteriorates
Solution Approach 1:
The patent changes the production parameter from hybridoma cell culture to recombinant bacterial expression. By cloning the VH and VL gene sequences into E. coli expression vectors and inducing protein production, the system achieves identical antigen-binding specificity while eliminating batch-to-batch variability associated with biological antibody production, thereby improving batch stability
3Measurement precision
If traditional detection methods are used, then detection accuracy is improved, but operational complexity increases
Solution Approach 1:
The patent introduces scFv fragments as intermediary detection elements that can be integrated into various assay formats (ELISA, immunochromatography, immunosensors). These scFv-based detection systems maintain the accuracy of traditional methods while simplifying operations through standardized protocols and reduced sample preparation requirements, making them accessible to non-specialist operators
Data Source
AI summary
Disclosed are a preparation method and application of a single-chain antibody fragment targeting SARS-CoV-2 nucleocapsid protein, aiming to provide a single-chain antibody fragment with high affinity and strong specificity. The present disclosure obtains three single-chain antibody fragments targeting SARS-CoV-2 nucleocapsid protein through construction of a nanobody phage library and phage screening technology. The single-chain antibody fragment consists of a heavy chain variable region, a 15aa connecting peptide, and a light chain variable region connected in sequence, and has an amino acid sequence shown in SEQ ID NO: 1-SEQ ID NO: 3. The single-chain antibody fragment in the present disclosure has excellent binding performance and specificity with the SARS-CoV-2 nucleocapsid protein, can be applied to a variety of immunoassay platforms of the SARS-CoV-2, and has broad application prospects in the field of SARS-CoV-2 detection.