THE EFFECT OF DENGUE VIRUS 2 ENVELOPE PROTEINS AS VACCINE ANTIGENS ON NEUTRALIZING ANTIBODY RESPONSES

The four dengue virus (DENV) serotypes cause several hundred million infections annually. Several live-attenuated tetravalent dengue vaccines (LAVs) are at different stages of clinical testing and regulatory approval. A major hurdle faced by the two leading LAVs is uneven replication of vaccine serotypes stimulating a dominant response to one serotype at the expense of the other three which could lead to an increased likelihood of severe dengue. Protein subunit vaccines are a promising alternative since antigen dosing can be precisely controlled. However, DENV envelope (E) protein subunit vaccines have not performed well to date, possibly due to differences between the monomeric structure of soluble E and the E homodimer of the viral surface. My dissertation work seeks to determine how DENV2 E antigen structure influences the properties of the resulting Ab response in mice. We combined structure-guided computational and experimental approaches to design and produce DENV2 E antigens that are stable homodimers at 37℃. We showed that DENV2 E stable homodimer were able to elicit higher levels of neutralizing antibodies (NAbs) than the WT E antigen in mice. Furthermore, using DENV4/2 chimeric viruses and Ab depletion methods, we were able to show that NAbs elicited by WT E vs DENV2 E homodimers target different epitopes on the E protein. We mapped the WT E-elicited NAbs to simple epitopes on domain III of E. In contrast, the stable E homodimer stimulated a more complex response towards all three surface-exposed domains of the E protein. Our findings highlight the impact of DENV2 E oligomeric state on the quality and specificity of DENV NAbs, and the promise of DENV E homodimers as subunit vaccines.