Stronger together Stabilizing the interactions between HCV E1 and E2 for vaccines

Hepatitis C virus (HCV) infection places a major burden on global health, affects 50 million people and causes 250,000 yearly deaths. Yet, there is no HCV vaccine available. The only target for neutralizing antibodies against HCV is the E1E2 glycoprotein on the virion surface. Eliciting broadly neutralizing antibodies that recognize conserved cross-neutralizing epitopes is important for an effective HCV vaccine. Furthermore, standardized tools to study immune responses and vaccine effectiveness are needed to help in vaccine development. This thesis explores both the design of vaccines against HCV and the tools needed to evaluate the immune responses. The first section focuses on refining in vitro methodologies to study antibody responses against HCV and on the study of a family of broadly neutralizing antibody (bNAbs) that targets an antigenic region that overlaps with the receptor binding site of HCV and that has been the focus of many vaccine strategies. The second part of the thesis is then focused on antigen design, where different design strategies are explored and protein engineering strategies culminate in the design of a stabilized soluble E1E2 that does not require dimerization domains to resemble the native E1E2. The set of stabilizing mutations is applied to different strains of HCV and even to a synthetic sequence generated from the consensus sequences of 10 major subtypes of HCV, which results in an antigenically superior immunogen. The results of this thesis are a milestone for HCV vaccine design and provide the foundations for the next generation of vaccines against HCV.