Vaccines have saved more lives than any other medical intervention. Recombinant vaccines provide unmatched safety profiles, but at the expense of reduced immunogenicity. Virus-like particles (VLPs) resemble viruses in size, shape and repetitive arrangement but are devoid of pathogenic genetic material and therefore safe. Poor immunogens can be rendered immunogenic by display on VLPs. Successfully decorating VLPs is still a major challenge. Genetic fusion or chemical modification is often time-consuming and can lead to misassembly or misfolding, which obstructs generation of the desired immune response. SpyCatcher is a genetically encodable protein, previously engineered to form a covalent isopeptide bond to its peptide-partner SpyTag. Presented in this thesis are SpyCatcher-VLPs, based on the fusion of SpyCatcher to the bacteriophage VLP AP205. SpyCatcher- VLPs can be conveniently conjugated with SpyTag fused antigens, simply by mixing. I demonstrate the modularity of this approach by covalently linking several complex, cysteine-rich malarial antigens to SpyCatcher-VLPs, such as the transmission-blocking antigen Pfs25 and the blood-stage antigen CIDR. A single administration of Pfs25-SpyTag conjugated to SpyCatcher-VLPs induced potent antibody generation against Pfs25, even in the absence of adjuvant. Anti-Pfs25 antibodies induced by this platform conveyed potent transmission-blocking activity in the mosquito vector. The thesis further demonstrates the feasibility of more complex Catcher-nanoparticle architectures. The previously engineered SnoopCatcher covalently reacts with SnoopTag peptide and is orthogonal to the SpyCatcher / SpyTag pair. IMX313 is an engineered chimera of the multimerization domain of chicken complement inhibitor C4-binding protein. This work describes fusion of SnoopCatcher and SpyCatcher to IMX313, which yields independently addressable Catcher-moieties on a single IMX313 nanoparticle. Display of two antigens on one particle may enable single-particle, multi-disease vaccines as well as multi-stage vaccines to tackle immune evasion of parasites. The platforms presented should accelerate and enhance vaccine development and may create opportunities for imaging and metabolic engineering.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:740792 |
| Date | January 2016 |
| Creators | Brune, Karl Dietrich |
| Contributors | Howarth, Mark |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://ora.ox.ac.uk/objects/uuid:41d57165-6e7c-4ca7-8025-b5ec31794c8c |
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