Investigation of functionalized carbon nanotubes as a delivery system for enhanced gene expression with implications in developing DNA vaccines for hepatitis C virus

Abstract

Hepatitis C virus (HCV) causes a significant health problem worldwide due to the lack of effective vaccines. It has been recognized that a rapid, vigorous, and broadly targeted cell-mediated immune response (Th1-like) is often associated with the clearance of HCV infections. DNA vaccines represent a promising means for HCV vaccination because they tend to induce a Th1-biased cell-mediated response in the host cell. Currently, the delivery of DNA vaccine for HCV in large animals as well as in humans is not as effective as in small animals. Nano delivery systems would be a promising approach to overcome this problem. Carbon nanotubes (CNTs) have been extensively studied for delivering drugs, proteins, peptides, and nucleic acids including plasmid DNA to cells and organs with varying degrees of success, but few of them have been applied to DNA vaccine for HCV.

This thesis presents a study of using functionalized CNTs (f-CNTs) to improve the efficacy of plasmid DNA vaccine delivery for HCV. First, CNTs were functionalized via 1,3-dipolar cycloaddition reaction with the appropriate amino acids and aldehydes. NMR and TEM results suggested that the CNTs were successfully functionalized and became soluble in water. Then plasmid DNAs which encode green fluorescence protein reporter gene, luciferase reporter gene, and HCV core protein, respectively, were delivered into human hepatoma cells via calcium phosphate precipitation method, f-CNT delivery system, and a combination of f-CNT and calcium phosphate method, respectively. The result showed that f-CNTs, in combination with the calcium phosphate method, significantly enhanced the gene expression in human hepatoma cells.

Consequently, this study concludes that the f-CNT can significantly enhance gene expression in liver cells conferred by a plasmid DNA when combined with calcium phosphate precipitation method. Even though the mechanisms of this enhancement await further investigation, the results of this thesis may have important implications in developing DNA vaccines for infectious diseases in general and for hepatitis C in particular.