Structure based design of dengue subunit vaccines for inducing protective but not disease enhancing antibodies

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ABSTRACT Dengue virus (DENV) vaccine development has been challenging because of the presence of 4 serotypes (DENV1-4) and the potential for vaccine enhanced severe disease. The leading live attenuated tetravalent DENV vaccines have been plagued by poorly balanced replication of vaccine components leading to variable efficacy and vaccine primed severe dengue disease in some children. The goal of this proposal is to develop novel recombinant DENV envelope (E) protein and virus like particle (VLP) vaccines that overcome barriers faced by live attenuated tetravalent vaccines. We have discovered that the DENV E protein produced as a secreted protein is a poor vaccine because it is a monomer that does not display major quaternary epitopes targeted by human neutralizing and protective antibodies (Abs). This proposal is based on new discoveries from our group about how structure based, computational approaches can be used to produce highly stable and properly folded DENV E dimers that are efficiently secreted from mammalian cells. We will use mouse models of DENV vaccination and infection to test if artificially stabilized DENV E dimers stimulate Ab responses that are similar to serotype-specific and serotype-cross-protective Ab responses in people exposed to primary and secondary wild type DENV infections. The stabilized E dimers will be further modified to test if large-scale resurfacing of the E dimer can be used to focus the immune response on epitopes recognized by potent neutralizing Abs, while eliminating responses to off target, disease enhancing epitopes. Finally, we will design membrane anchored variants of stabilized E dimers to promote the formation of dengue virus-like particle (VLP) vaccine candidates that better resemble mature infectious virions than VLPs made with current techniques. Our studies, which explore how to design and deliver recombinant E antigens to focus the host antibody response on important quaternary structure neutralizing epitopes, will stimulate new research directions in the field of flavivirus subunit vaccines.