Date of Award

Fall 12-18-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Pharmaceutical Sciences

First Advisor

Tatiana K. Bronich

Abstract

Hepatitis C Virus (HCV) is recognized as a major burden in global public health, which can be further exacerbated by several cofactors such as human immunodeficiency virus (HIV). Currently, there is no vaccine for HCV. The emergence of potent and highly specific direct-acting antivirals (DAA) has marked a new era in HCV therapy, however, the remaining issues like affordability, genotype dependency, and potential resistance still necessitate the development of additional therapeutic approaches to be used instead or in combination with DAA.

Recently, the antiviral peptide C5A (in our studies designated as p1) and its cationic derivative p41 have been identified as potent antiviral agents. Predominantly due to the α-helicity and amphipathicity, p1 and p41 exhibit submicromolar virocidal effect against HCV, other members of the Flaviviridae, and HIV. However, the clinical translation of peptide drugs is impeded by the susceptibility to degradation, and, particularly for the cationic peptide p41, unfavorable cytotoxicity. To address these limitations, we propose to use the polymeric materials as delivery vehicles for peptide stabilization and reduced toxicity associated with the positive charge.

Antiviral Peptide Nanocomplexes (APN) were developed based on the electrostatic coupling of cationic p41 and biodegradable anionic poly(amino acid)-based block copolymers, and they have been extensively characterized with a variety of analytical and biophysical techniques. The immobilization of the peptide into APN led to improved stability, reduced cytotoxicity and unaltered anti-HIV/HCV potency of the peptides in vitro. Moreover, in vivo APN were able to decrease the HIV-1 viral load in mice model. By further modifying the APN surface with liver-targeting ligand galactose (Gal-APN), liver-specific delivery system of p41 was developed as a more selective therapy against HCV. In vitro, Gal-APN displayed specific internalization in hepatoma cell lines. Even though liver-targeted and non-targeted APN displayed comparable antiviral activity, Gal-APN offered prominent advantages to prevent HCV association with lipid droplets and suppress intracellular expression of HCV proteins. Moreover, in vivo preferential liver accumulation of Gal-APN was revealed in the biodistribution study. The feasibility of DAA and p41 as synergistic combination against HCV was also tested by preparing a series of poly(amino acid)-based micelles loaded with DAA and p41 simultaneously.

The parental peptide p1 was incorporated into the PEG-phospholipid micelles. The formulation was prepared and characterized with multiple techniques. After p1 is encapsulated into micelles, the stability of p1 against the proteolytic degradation was delayed, and the anti-HCV/HIV activity was preserved.

Collectively, we demonstrated that APN approach represents a promising platform for the delivery of antiviral peptide p41 with enhanced stability and reduced toxicity, and its liver-targeted delivery can be achieved by modifying the APN surface with hepatocyte-specific ligand galactose. The encapsulation of DAA and p41 in poly(amino acid)-based micelles may provide potential opportunities as synergistic anti-HCV therapy. We have also developed the p1-loaded PEG-phopholipid micelles with enhanced stability and preserved antiviral activity. These results demonstrate the power of polymer-based nanoparticulate systems for antiviral peptide delivery and their potential for bench-to-bedside translation.

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