Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Microbiology and Immunology

Supervisor

Dikeakos, Jimmy D

Abstract

The human immunodeficiency virus type 1 (HIV-1) protein, Nef, binds and activates Src family kinases (SFKs) to reduce cell surface levels of major histocompatibility complex class I (MHC-I), thereby facilitating cytotoxic T lymphocyte (CTL) evasion. Importantly, Nef-mediated CTL evasion compromises the success of immune-directed curative approaches, underscoring Nef:SFK interaction inhibitors as promising adjuvants in an immune-directed cure. Previously, our group identified a dipeptide derivative (H3-1) which inhibits the Nef:SFK interaction and MHC-I downregulation in vitro, but is unstable in vivo. I hypothesized that H3-1’s instability is due to its proteolysis and have generated peptidomimetic analogues of H3-1 which are predicted to maintain improved proteolytic stabilities. Herein, I describe the design and synthesis of analogues incorporating carboxyl (methyl ester, amide, nitrile, and tetrazole) and amide (thioamide and methyleneamino) replacing groups. With future biological studies, we aim to identify an in vivo stable Nef:SFK inhibitor for application in an immune-directed HIV-1 cure.

Summary for Lay Audience

To-date, there is still no practical cure for human immunodeficiency virus type 1 (HIV-1) infection. Many curative approaches in development rely on specific immune cells, known as cytotoxic T lymphocytes (CTLs), to recognize and kill HIV-1-infected cells. However, HIV-1 maintains mechanisms to evade CTL recognition and killing, which compromises the success of these cures. One of the key mechanisms for HIV-1’s evasion of CTL killing is mediated by the HIV-1 protein, Nef. Specifically, Nef enables HIV-1-infected cells to avoid CTL recognition by reducing cell surface levels of the antigen presenting molecule, major histocompatibility complex class I (MHC-I). Importantly, this process depends on Nef’s interactions with a set of signaling molecules, termed Src family kinases (SFKs), which highlights the Nef:SFK interaction as a target for therapeutic intervention. We therefore predict that inhibitors of the Nef:SFK interaction could be applied as adjuvants in an immune-directed HIV-1 cure to boost the CTL-mediated killing of infected cells.

Previously, our group identified a dipeptide derivative, termed H3-1, which inhibits the Nef:SFK interaction and rescues cell surface levels of MHC-I in vitro. However, H3-1 was found to be unstable in vivo, thereby precluding its therapeutic application. Considering H3-1’s peptidic structure, I hypothesized that H3-1’s in vivo instability is due to its susceptibility to proteolysis. In this thesis, I used organic synthesis to generate a panel of H3-1 analogues which are predicted to maintain improved proteolytic stabilities and should thereby enable their continued study as supportive agents in an HIV-1 cure. Specifically, I synthesized and isolated four peptidomimetic analogues incorporating replacements of H3-1’s carboxylic acid group (methyl ester, amide, nitrile, and tetrazole). Attempts to synthesize analogues incorporating replacements of H3-1’s amide group (thioamide and methyleneamino) were also made and are described herein. With this panel of H3-1 analogues, future studies will focus on characterizing these compounds biologically on measures of toxicity, potency, and biostability. By integrating each of these parameters, we aim to identify a next-generation in vivo stable Nef:SFK interaction inhibitor for application in an immune-directed HIV-1 cure.

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