By-passing immunization: building high affinity human antibodies by chain shuffling

Area of Science:

• Immunology
• Molecular Biology
• Biotechnology

Background:

• Phage display technology enables in vitro generation of human antibodies, mimicking natural immune responses without prior immunization.
• Antibody affinity maturation is crucial for developing effective therapeutics and research tools.
• Existing methods for affinity improvement often rely on random mutagenesis.

Purpose of the Study:

• To improve the affinity of a human phage antibody against the hapten 2-phenyloxazol-5-one (phOx).
• To evaluate the efficacy of chain shuffling for antibody affinity maturation.
• To compare the reshuffling approach with random point mutation for enhancing antibody binding.

Main Methods:

• Utilized phage display to select human antibodies from diverse libraries.
• Employed chain shuffling by sequentially replacing heavy and light chain variable (V) region genes with repertoires from unimmunized donors.
• Focused on reshuffling hypervariable loops of the antibody's V-regions.

Main Results:

• Achieved a 20-fold affinity improvement by shuffling light chains.
• Obtained a further 15-fold affinity increase by shuffling the first two heavy chain hypervariable loops.
• Developed a reshuffled antibody with a final dissociation constant (Kd) of 1.1 x 10(-9) M, comparable to antibodies from tertiary immune responses.

Conclusions:

• Chain shuffling is an effective strategy for in vitro antibody affinity maturation.
• This method allows for significant enhancement of human antibody affinity without prior immunization.
• Reshuffling offers a viable alternative to random point mutation for optimizing antibody binding properties.