Validation of the human antibody fragment library – scFv – using the phage display technique against targets of diverse nature

Introduction:The development of therapeutic antibodies is of utmost importance for oncological, infectious, and immune checkpoint treatments.Antibodies can be predominantly developed through hybridoma technology followed by humanization or via phage display.The phage display technology, which is based on the use of filamentous bacteriophages that incorporate exogenous genes with diversity to form a library, presents an excellent alternative for the development of fully human antibodies.The main advantages of this platform include the generation of a repertoire of non-natural human antibodies, independent of in vivo immune responses, and it can be applied to obtain monoclonal antibodies (mAbs) against any type of antigen, such as autoantigens, toxic antigens, unstable and non-immunogenic antigens.Objectives: To compare the human antibody fragment library -scFv -against a human target and a fungal target.Methodology: Use of a human scFv library for bioslection of scFv against human and fungal protein targets.The same molar concentration (50, 25, and 10 nM) and selection methodology (selection time, culture, and expression of scFv) were applied.After selection, the fragments were evaluated for specificity through immunoenzymatic assays.Results: The selection cycles followed the same pattern, but it was not possible to go beyond Cycle 3 for the human target and Cycle 2 for the fungal target.Against the human target, a 22-fold enrichment and selection of scFv were achieved compared to the negative control, with no difference in the second cycle.For the fungal target, a 14-fold enrichment was obtained in the first cycle, and no enrichment was observed in the second cycle.It is worth noting that the clones selected for scFv expression against the selected targets showed positive immunoenzymatic results, demonstrating that regardless of the target, the library is effective, and its methodology is valid. Conclusion:The use of the human antibody fragment library for scFv selection through the phage display technique was effective in identifying different targets of diverse nature, demonstrating that regardless of the target, the human library is suitable for selection.