Wuxun Lu

Document Type

Thesis - University Access Only

Award Date

2011

Degree Name

Doctor of Philosophy (PhD)

Department / School

Biology and Microbiology

Abstract

3-0-(3 ',3 '-dimethylsuccinyl) betulinic acid (DSB), also known as PA-457 or Bevirimat (BVM) or MPC-4326, is a novel HIV-I maturation inhibitor. Unlike protease inhibitors, BVM blocks the cleavage of the Gag capsid precursor (CA-SPl) to mature capsid (CA) protein resulting in the release of immature, non-infectious viral particles. Despite the novel mechanism of action and initial progress made in small-scale clinical trial's, further development of BVM has encountered unexpected challenges, because patients whose viruses contain genetic polymorphisms in the Gag SPl (positions 6 to 8) protein do not generally respond well to BVM treatment. To better define the role of amino acid residues in HIV-I Gag SPl protein involved in natural polymorphisms to confer resistance to the HIV- I maturation inhibitor BVM, a series of Gag SP I chimeras involving BVM sensitive (subtype 8) and BVM resistant (subtype C) viruses were generated and characterized for their sensitivity to BVM. We show that SPI residue 7 of the Gag protein is a primary determinant of SP I polymorphism-associated drug resistance to BVM. To further study the role of C-terminal region of SP 1 involves in the molecular determinants of BVM susceptibility, we generated HA-tagged HIV- I pseudoviruses. In the presence of A 1V, HA 7 virus shows susceptibility to BVM treatment, while A 1V mutation in HA8 and HA9 results in more infectious viruses in the presence of BVM. These results suggest a stable BVM binding site or structure in HA 7 that is not affected by Al V mutation. Results also suggest similar but less stable structures in HA8 and HA9, which are disrupted by A 1V mutation. These results further expand our understanding of SPl-BVM interaction and show C-terminal region of SPl involve the formation of structure interacting with BVM. In spite of Al V mutation, HA 7 resembles BVM sensitivity of wild type, indicating its high similarity to wild type virus in the structure and maturation processes, which make it an ideal clone for investigation of SPl localization and functions in virion and host cells

Library of Congress Subject Headings

HIV (Viruses) -- Enzymes -- Inhibitors

Antiviral agents

Format

application/pdf

Number of Pages

85

Publisher

South Dakota State University

Download

Share

COinS