Approaches towards molecular construction of a synthetic vaccine against Hepatitis C virus

In this work, an alternative strategy involving a fully synthetic approach is being investigated toward structure-based vaccine design against HCV. The main focus is being put on the HCV envelope E2 glycoprotein, which is a viral protein that is present on the outside of the virus particle and essential in establishing infection. Extensive research on the E2 glycoprotein has yielded an enormous amount of information dictating highly conserved domains to which the immune system can efficiently respond in order to neutralize the virus and even naturally cure infection. These highly conserved and neutralizing domains, together with the availability of antibodies binding these regions, will be exploited to design synthetic peptide-based modulators (i.e. epitope mimics) towards a prophylactic vaccine against hepatitis C virus. This methodology is based on a modular approach that allows for fast and easily modifiable vaccines that can quickly respond to the rapidly mutating nature of HCV and predicted outbreaks of specific strains. The difficulty of identifying a generic consensus epitope that shows effective antigenicity and immunogenicity across the diverse range of HCV variants could be bypassed this way. The design of epitope mimics is highly influenced by the spatial configuration and structural conformation of the native epitope within the overall protein structure. Synthetic peptides on molecular scaffolds can take a desired epitope out of the context of the viral protein, while maintaining its correct structural and spatial conformation. Therefore, the major bulk of the protein can be omitted to circumvent unwanted incorporation of potential immune-evasive domains in the vaccine. This thesis starts by providing a general introduction of HCV in the context of its global burden, life cycle, impact on the immune system, and considerations with respect to vaccine design (Chapter 1). This is followed by investigation of the impact of introducing conformational constraints on synthetic epitope mimics, by peptide cyclization, on antibody binding (Chapter 2). Next, epitope mimics were synthesized using novel polar hinges to improve their aqueous solubility and re-validated their biological activity (Chapter 3). Then, the work presented culminates in the construction of a complex fully synthetic epitope mimic presenting three individual epitopes conjugated onto a molecular scaffold and its potential for vaccination was investigated (Chapter 4)