Construction of Synthetic Antibody Libraries

Central Nervous System Delivery of Antibodies and Their Single-Domain Antibodies and Variable Fragment Derivatives with Focus on Intranasal Nose to Brain Administration

IgG antibodies are some of the most important biopharmaceutical molecules with a high market volume. In spite of the fact that clinical therapies with antibodies are broadly utilized in oncology, immunology and hematology, their delivery strategies and biodistribution need improvement, their limitations being due to their size and poor ability to penetrate into tissues. In view of their small size, there is a rising interest in derivatives, such as single-domain antibodies and single-chain variable fragments, for clinical diagnostic but also therapeutic applications. Smaller antibody formats combine several benefits for clinical applications and can be manufactured at reduced production costs compared with full-length IgGs. Moreover, such formats have a relevant potential for targeted drug delivery that directs drug cargo to a specific tissue or across the blood–brain barrier. In this review, we give an overview of the challenges for antibody drug delivery in general and focus on intranasal delivery to the central nervous system with antibody formats of different sizes.

Synthesis of libraries and multi-site mutagenesis using a PCR-derived, dU-containing template

Directed DNA libraries are useful because they focus genetic diversity in the most important regions within a sequence. Ideally, all sequences in such libraries should appear with the same frequency and there should be no significant background from the starting sequence. These properties maximize the number of different sequences that can be screened. Described herein is a method termed SLUPT (Synthesis of Libraries via a dU-containing PCR-derived Template) for generating highly targeted DNA libraries and/or multi-site mutations wherein the altered bases may be widely distributed within a target sequence. This method is highly efficient and modular. Moreover, multiple distinct sites, each with one or more base changes, can be altered in a single reaction. There is very low background from the starting sequence, and SLUPT libraries have similar representation of each base at the positions selected for variation. The SLUPT method utilizes a single-stranded dU-containing DNA template that is made by polymerase chain reaction (PCR). Synthesis of the template in this way is significantly easier than has been described earlier. A series of oligonucleotide primers that are homologous to the template and encode the desired genetic diversity are extended and ligated in a single reaction to form the mutated product sequence or library. After selective inactivation of the template, only the product library is amplified. There are no restrictions on the spacing of the mutagenic primers except that they cannot overlap.

Efficient Construction and Effective Screening of Synthetic Domain Antibody Libraries

Phage display is a powerful technique for drug discovery in biomedical research in particular for antibody libraries. But, several technical challenges are associated with the selection process. For instance, during the panning step, the successful elution of the phages bound to the antigen is critical in order to avoid losing the most promising binders. Here, we present an efficient protocol to establish, screen and select synthetic libraries of domain antibodies using phage display. We do not only present suitable solutions to the above-mentioned challenges to improve elution by 50-fold, but we also present a step by step in-depth protocol with miniaturized volumes and optimized procedures to save material, costs and time for a successful phage display with domain antibodies. Hence, this protocol improves the selection process for an efficient handling process. The here presented library is based on the variable domain (vNAR) of the naturally occurring novel antibody receptor (IgNAR) from cartilage fishes. Diversity was introduced in the Complementarity-Determining Region 3 (CDR3) of the antigen-binding site with different composition and length.