Date of Completion

3-11-2019

Embargo Period

3-7-2024

Keywords

Vaccine, GIP, Obesity, Nanoparticle, SAPN

Major Advisor

Charles Giardina

Associate Advisor

Peter Burkhard

Associate Advisor

Eric May

Associate Advisor

Victoria Robinson

Associate Advisor

Irina Rybina

Field of Study

Molecular and Cell Biology

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Vaccines are one of the most impactful inventions in modern medicine and are responsible for significant improvements in public health. While various vaccine types are available, subunit vaccines have substantial interest in the field. Typical subunit vaccines are advantageous because they are considered safe; however, they often do not elicit strong immune responses because they cannot crosslink B cell receptors. To overcome this, repetitive display systems are used. Here we study an exciting platform called Self-Assembling Protein Nanoparticles (SAPNs), which contain coiled-coil oligomerization domains that self-assemble into nanoparticles similar in size and shape to icosahedral viruses. Previous work has demonstrated that SAPNs can successfully induce immune response and protection against diseases including SARS, malaria, HIV, and avian flu.

Here we sought to optimize the SAPNs with the addition of an immunopotentiator creating self-adjuvanted SAPNs. We explored two different adjuvants, flagellin, and CpG. Both have previously demonstrated their effects to enhance immune response. In this work, we first explore the biophysical properties of the self-adjuvanted SAPNs with flagellin. Various techniques including dynamic light scattering (DLS) and analytical ultracentrifugation (AUC) demonstrated the stability of self-adjuvanted SAPNs. Next, this SAPN was used to study obesity using glucose-dependent insulinoptropic polypeptide (GIP). The primary role of GIP is stimulation of glucose dependent insulin secretion, which has been linked to obesity. Unfortunately, our initial study yielded limited immune responses against GIP. Therefore, additional optimization of the SAPN was completed to encapsulate CpG. Here, the immune response against the SAPN was higher than that against GIP. Further studies led to the understanding that there is a diversion of the immune response from GIP to flagellin. This is largely driven by the inherent immunodominance of flagellin; however, the fact that GIP is a self-peptide contributes to the limited immune response. Ultimately, the SAPN with the highest antibody titers is self-adjuvanted SAPN without flagellin, but with CpG encapsulation. Future work can be completed to find conditions that target the immunostimulation of flagellin against GIP. Overall, we have identified a self-adjuvanted SAPN that is able to generate high antibody titers against GIP and could be a promising vaccine candidate.

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