Problems of creating antibody phage libraries and their solutions.

Phage display has become an efficient, reliable and popular molecular technique for generating libraries encompassing millions or even billions of clones of divergent peptides or proteins. The method is based on the correspondence between phage genotype and phenotype, which ensures the presentation of recombinant proteins of known amino acid composition on the surface of phage particles. The use of affinity selection allows one to choose variants with affinity for different targets from phage libraries. The implementation of the antibody phage display technique has revolutionized the field of clinical immunology, both for developing tools to diagnose infectious diseases and for producing therapeutic agents. It has also become the basis for efficient and relatively inexpensive methods for studying protein-protein interactions, receptor binding sites, as well as epitope and mimotope identification. The antibody phage display technique involves a number of steps, and the final result depends on their successful implementation. The diversity, whether natural or obtained by combinatorial chemistry, is the basis of any library. The choice of molecular techniques is critical to ensure that this diversity is maintained during the phage library preparation step and during the transformation of E. coli cells. After a helper phage is added to the suspension of transformed E. coli cells, a bacteriophage library is formed, which is a working tool for performing the affinity selection procedure and searching for individual molecules. Despite the apparent simplicity of generating phage antibody libraries, a number of subtleties need to be taken into account. First, there are the features of phage vector preparation. Currently, a large number of phagemid vectors have been developed, and their selection is also of great importance. The key step is preparing competent E. coli cells and the technology of their transformation. The choice of a helper phage and the method used to generate it is also important. This article discusses the key challenges faced by researchers in constructing phage antibody libraries.

The Search for Single-Domain Antibodies Interacting with the Receptor-Binding Domain of SARS-CoV-2 Surface Protein.

We performed a search for nanoantibodies that specifically interact with the receptor-binding domain (RBD) of the SARS-CoV-2 surface protein. The specificity of single-domain antibodies from the blood sera of a llama immunized with RBD of SARS-CoV-2 surface protein S (variant B.1.1.7 (Alpha)) was analyzed by ELISA. Recombinant trimers of the SARS-CoV-2 spike protein were used as antigens. In this work, a set of single-domain antibodies was obtained that specifically bind to the RBD of the SARS-CoV-2 virus.