African horse sickness (AHS) is a devastating disease of many equids and in the absence of effective treatment, vaccination plays an important role. Concerns of the commercially available live attenuated vaccine have stimulated the development of novel recombinant vaccines. The viral protein VP7 of AHSV induces high levels of antibody in infected horses. Both viral replication, and expressed VP7 in insect cells, results in the generation of hexagonal crystalline structures composed entirely of VP7 (~5pm in diameter). The aim of this thesis was to explore the immunogenicity of VP7 crystals and their potential as a novel vaccine delivery platform. Firstly, successful expression of AHSV-4 VP7 was characterised in vitro using recombinant baculovirus and live vaccinia vectored systems. These provided the necessary tools to explore VP7 crystal immunogenicity. Pilot VP7 vaccination studies were conducted in the equine and mouse animal model. Secondly, insertions of AHSV-4 VP2a peptide into VP7 at amino acid position 200 did not compromise the ability of the modified VP7 constructs to form crystals and allowed investigations of the immunogenicity of VP7/VP2a200 in the mouse animal model. This project demonstrated that VP7 crystals were poor immunogens in the absence of adjuvant and multiple vaccinations. However, immunogenicity was Improved when crystals were partially solubilised with urea, indicating that soluble VP7 was more immunogenic than VP7 crystals. Hence, crystal generation may provide a mechanism for immune evasion in AHSV infection. Nevertheless, both VP7/VP2a200 untreated crystals and urea treated VP7/VP2a200 crystals induced insert-specific antibodies. Importantly, VP2a peptide antibodies raised against urea treated crystals induced low levels of AHSV-4 neutralisation in vitro. Future work should include exploring the immunological and protective potential of soluble VP7 and further Investigating the use of VP7 as a vaccine platform.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:718669 |
| Date | January 2016 |
| Creators | Bailey, Laura Victoria |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/55842/ |
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