Computer-based Design of Dengue Virus Vaccine Antigens

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ABSTRACT Dengue virus (DENV) infections have been on the rise over the past three decades, with ~390 million people infected each year. Many of these infections result in severe clinical manifestations, including dengue hemorrhagic fever, dengue shock syndrome and death. Included in these statistics are infections reported in the US, such as the outbreak in Florida in 2013, and the more recent outbreak in Hawaii in 2016. DENV vaccine development has been challenging due to the prevalence of four DENV serotypes and the potential for immune enhancement of disease. The only licensed vaccine for DENV, Dengvaxia, a live-attenuated vaccine containing all four DENV serotypes, has been met with limited success as it only provides partial protection between DENV serotypes, and has been shown to increase the risk of severe dengue disease when used in dengue uninfected people. These facts display the urgent need to explore alternative vaccine strategies that are capable of providing broad protection against all DENV serotypes. We and other groups have shown that people who have been infected by DENV, develop antibodies that recognize a quaternary structural epitope which spans the viral envelope (E) protein dimer that is presented naturally on the assembled viral surface. A class of these isolated human antibodies which recognize this quaternary E protein dimer epitope (EDE) have recently been shown to broadly neutralize each of the DENV serotypes. Our proposal is grounded on the recently discovered structural biology of these EDE broadly neutralizing antibodies (Abs) which provides atomic resolution of the conserved epitope targeted by these Abs. These EDE Abs also recognize the soluble recombinant version of the DENV E protein (sRecE), a promising subunit vaccine antigen. However, under physiological conditions, the DENV sRecE antigen is predominantly monomeric in solution, and is prone to aggregation due to low monomer thermostability, limiting the protein’s presentation of EDE epitopes, and its use as a subunit vaccine. Our proposal is to leverage the existing structural information of these human EDE broadly neutralizing antibodies, and computational protein design, to engineer and produce stable EDE-epitope focused DENV sRecE protein dimers as vaccine antigens. In future studies, these stable DENV sRecE dimer antigens will be used as vaccine candidates to assess their ability to elicit broadly neutralizing EDE Abs and provide protection against DENV infection.