Developing phage display technologies for novel sheep antibody production

The increased need for antibody based biological products as therapeutics, diagnostics and other research tools asks for continuous investigation to make available new and highly diverse variants. Animal derived antibodies have helped in addressing this challenge due to the unique immune systems of many species which can provide natural antibody diversity. Developing an antibody product requires the encoding DNA sequence, enabling reproducibility and genetic manipulation to improve binding affinity and stability. Of the known antibody production methods, phage display antibody libraries offer the best choice for providing highly diverse antibodies that have a direct link to their genetic sequence. This project collaborated with Ig-Innovations Ltd through the CALIN network to investigate the creation of a sheep antibody library through phage display and if this allows selection of antibody fragments. This thesis provides detailed method development for the creation of an antibody phage display library using sheep (Ovis aries) antibody sequences as a source of repertoire diversity. The method required the development of primers to amplify the antibody repertoire, a sheep compatible plasmid and a cloning method to create a library. Using this developed method, an antibody library was created from the peripheral blood lymphocytes of sheep immunised with a tetraspanin membrane protein conjugated to an immune adjuvant. Library screening through bio-panning was able to retrieve a complete sheep antibody sequence, proving that the method was functional. This study highlights important design and methodological considerations that are needed to acquire a new antibody phage display library from underutilised animal sources. This developed and novel method provides an opportunity to produce antibody fragments from immunised sheep, allowing for antibody discovery. It represents a new enabling technology for the Cardiff University School of Pharmacy and our industrial collaborators