All ETDs from UAB

Advisory Committee Chair

Matthew B Renfrow

Advisory Committee Members

Susan L Bellis

Todd J Green

Jan Novak

William J Placzek

Document Type

Dissertation

Date of Award

2019

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

In 2017, there was an estimated 1.8 million new HIV-1 infections worldwide. Development of an effective HIV-1 vaccine would begin to quell this global pandemic. HIV-1 envelope (Env) glycoprotein is the main vaccine candidate target due to the immune systems ability to generate broadly neutralizing antibodies (bnAbs) against Env. Approximately 90 N-glycans form a glycan shield that is the primary interface between the virus and host immune system. Key glycan motifs within the glycan shield are targets for bnAbs and are necessary for HIV-1 infectivity. Herein, we explore how naturally occurring mutations alter the glycan shield and HIV-1 Env function. In the first section of this work, we utilize high-resolution mass spectrometry to track shifts in N-glycan heterogeneity due to immune escape viral variant mutations. This shift in heterogeneity defined a range of N-glycosylation sites (NGS) or sequons, which could be grouped into one confined structural region. We speculated that this information could be used as a basis for a mutation cluster analysis to define N-glycan microdomains within the N-glycan shield. Using the HIV-1 Los Alamos National Laboratory database, we define a finite number of sequons that corresponded to a microdomain and created an immune escape map of conserved and variable sequons. In the second section of this work, we tested how the same alterations in the glycan shield modified HIV-1 Env function. This was accomplished through a series of infectivity, binding, and neutralization assays. Through these analyses, we determined that when NGS N262 was present HIV-1 was more infective and had a higher binding affinity with soluble CD4. A 500 ns molecular dynamics simulation enabled us to visualize how the loss/gain of the N262 glycan altered the glycan shield corroborating the site-specific N-glycan heterogeneity data. By correlating glycomics, bioinformatics, and biological data, we can begin to make novel conclusions on how naturally occurring Env mutations alter the Env glycan shield function. Additionally, this data provides a means by which we can begin to anticipate HIV-1 Env immune evasion and provide details that will lead to the design of a better immunogen for an HIV-1 vaccine.

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