Conventional methods for treating chronic diseases such as HIV/AIDS have proven to be relatively inefficient both in terms of administration of therapeutic molecules and eradication of the underlying diseases themselves;while conventional antiretroviral therapy (ART) suppresses plasma viremia, low-level viral replication persist. Our recent findings have indicated that pigtailed macaques transplanted with gene-modified CD34+ cells expressing a membrane-anchored fusion inhibitor (mC46) develop infection-resistant CD4+ T-cells, maintain normal CD4+ T-cell levels, and develop an enhanced immune response against the SHIV-challenge virus resulting in a 300- to 1400-fold decrease in plasma viremia. Despite these very encouraging results, additional methods to further reduce plasma viremia to undetectable levels and/or potentially eliminate viral reservoirs will be required. Hence, we propose the development of a novel delivery system based on modifying hematopoietic stem cells (HSCs) or CD4+ T-cells in order to directly target viral reservoirs in vivo. The use of primary cells to deliver therapeutic peptides represents an innovative and ideal mode for systemically delivering therapeutic molecules throughout a patient's body. Furthermore, the ability of HSC-derived lineages to transverse both physiological and anatomical barriers represents a unique potential of this therapy. Low levels of engraftment would likely yield sufficient quantities of secreted antiretroviral peptides, while the efficiency f uptake would be greatly enhanced as there is a continuous source of the therapeutic molecules at sites typically thought to maintain persistent viral reservoirs. In order to deliver proviral targeting endonucleases to latent reservoirs, terminally differentiated primary cell such as CD4+ T-cells that migrate throughout lymphoid tissue represents the ideal vehicle. Hence, the goal of this study is to examine the feasibility of using genetically modified HSCs and CD4+ T-cells to secrete antiretroviral molecules to control viral replication and directly target latent reservoirsin vivo.
This application will develop novel strategies to deliver antiviral peptides and (S)HIV-specific nucleases to the latent reservoir. If successful, these studies would provide a major advancement for the development of alternative therapeutic approaches aimed at controlling viral replication in the absence of antiretroviral therapy and possibly lead to eradication of latent viral reservoirs in patients with HIV.