VHH Antibody Fusions for SARS-CoV-2 Neutralization
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Solution Overview
Problem
Current treatments for COVID-19, such as Remdesivir and passive immunization with polyclonal antibodies, have limitations including high costs, risk of antibody-dependent enhancement, and variability in monoclonal antibodies, while diagnostic methods face challenges in sensitivity and specificity for early infection detection.
Innovation Solution
Development of VHH antibodies that specifically target the SARS-CoV-2 spike protein, particularly the receptor-binding domain, with enhanced stability and the ability to neutralize the virus at low concentrations, including mutants, through the use of monovalent, heterodimeric, and homotrimeric forms, and their production in recombinant systems like Pichia yeast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyclonal antibodies are used for passive immunization, then neutralizing activity is achieved, but risk of antibody-dependent enhancement and batch-to-batch variability occurs
Solution Approach 1:
The patent extracts and utilizes only the antigen-binding variable domain (VHH) from the antibody molecule, discarding the Fc region that mediates harmful ADE effects. This is achieved by expressing VHH as a standalone protein or fusion protein without the constant regions that would otherwise bind Fc receptors.
Solution Approach 2:
The patent employs recombinant VHH proteins produced in bacterial or yeast expression systems as single-use, standardized therapeutic agents. These recombinant proteins replace expensive, variable polyclonal antibody preparations with standardized, scalable, and cost-effective monovalent or multimeric VHH constructs.
2Reliability
If monoclonal antibodies are used, then production reproducibility is improved, but cost and complexity of production increase
Solution Approach 1:
The patent segments the antibody into its functional variable domain (VHH) and non-functional constant regions. By expressing only the VHH portion in simple bacterial or yeast systems, the patent achieves monoclonal-like reproducibility without the complex mammalian cell culture infrastructure required for full IgG production.
Solution Approach 2:
The patent replaces the complex biochemical machinery of mammalian antibody production with simpler bacterial or yeast expression systems. This substitution maintains production reproducibility while dramatically reducing manufacturing complexity and cost.
3Reliability
If conventional antibodies are used, then virus neutralization is achieved, but stability and half-life may be insufficient
Solution Approach 1:
The patent merges the VHH antigen-binding domain with Fc regions of human IgG1 or IgG3 to create antibody fragments that retain long circulating half-life through FcRn-mediated recycling, while maintaining virus neutralization capability. This fusion combines the advantages of both VHH and conventional antibodies.
Solution Approach 2:
The patent creates composite antibody structures by fusing VHH domains with human IgG Fc regions, resulting in molecules that combine the stability and neutralization of VHH with the extended half-life and effector functions of conventional IgG.
4Adaptability or versatility
If Fc region is included in antibodies, then effector functions are provided, but risk of cytokine storm and complement activation increases
Solution Approach 1:
The patent extracts and utilizes only the antigen-binding variable domain (VHH) from the antibody molecule, discarding the Fc region that mediates harmful cytokine storm and complement activation. This is achieved by expressing VHH as a standalone protein or fusion protein without the constant regions that would otherwise bind Fc receptors.
Solution Approach 2:
The patent uses FcRn as an intermediary to extend the half-life of VHH proteins without requiring the inclusion of full Fc regions. The VHH-Fc fusion proteins interact with FcRn for recycling, providing extended circulation time while avoiding the harmful effector functions of complete Fc regions.
Data Source
AI summary
The present invention pertains in the fields of antibody technology, protein engineering, medicine, pharmacology, infection biology, virology, and medical diagnostics. More specifically, the present disclosure provides VHH antibodies that prevent cell entry of and infection by SARS-CoV-2, a strategy for an enhanced block of the homotrimeric viral spike proteins by symmetry-matching VHH-fusions, implementations of this strategy, as well as VHH antibodies for sensitive detection of SARS-CoV2-infections.