CXCR4 targeted peptide carriers for the inhibition of HIV and delivery of anti-viral drugs

HIV-1 continues to be a major epidemic affecting the global population and responsible for millions of deaths annually. Despite the mortality of the virus, great improvement in the currently available retroviral pharmacotherapy has lead to a chronic treatment of infected individuals. However the current therapy is not a cure for HIV-1 infection and eventually drug resistant viral strains will deplete the infected individual of CD4+ T cells. The chemokine receptor CXCR4 plays an important role to HIV-1 infection of host cells. CXCR4 acts as a coreceptor to viral entry. CXCR4 is expressed several types of HIV-1 susceptible cells and therefore has been identified as a target for anti-viral intervention as well as a targeted drug delivery system. The thesis herein is focused developing peptide drug conjugates targeting CXC4. Peptide carriers were synthesized to specifically interact with CXCR4 by the targeting sequence DV3. Multivalent DV3 peptide carriers containing 1, 2, or 4 copies of the CXCR4 targeting sequence DV3 were tested in vitro for the inhibition of HIV-1 entry and cellular uptake via confocal microscopy. Only the 4 copy DV3 peptide carriers (4DV3) significantly inhibited HIV-1 from infecting the reporter cell line TZM-bl and were entrapped within cellular endosomes. 4DV3 inhibited the HIV-1 strain IIIB in vitro (IC50=553nM). The small molecule, AMD3100 (47%), and a CXCR4 monoclonal antibody (IC50 = 398nM) inhibited the 4DV3/CXCR4 interaction. Molecular modeling of 4DV3 interacting with CXCR4 demonstrated the ability of 4DV3 to interact with a tetramer of the receptor. 4DV3 was further modified to carry drug cargoes with known anti-viral activity. Comparative analysis of the peptides carrier’s ability to enhance the anti-HIV activity of the drug, the 4DV3, or act synergistically was investigated. 4DV3 conjugates of AZT (IC50=32nM) and RTV (IC50=598nM) improved the effectiveness of 4DV3 (IC50=23μM) inhibition of HIV-1 replication. The stability of the ester drug conjugate was evaluated over time. Finally, third generation compounds were designed and synthesized to increase the drug loading. The studies that have been performed were designed to evaluate the potential of a targeted CXCR4 peptide carrier as a drug delivery system for HIV-1 therapy.Ph. D.Includes bibliographical referencesby Matthew S. Palomb