HIV-1 infection requires a life-term antiretroviral treatment because its cessation leads to rapid viral rebound from the HIV-1 latent cellular/tissue reservoir. Novel approaches to eradicate or permanently silence HIV-1 proviruses are urgently needed to achieve a ?sterile? cure of HIV infection, for which CRIPSR/Cas9 genome editing has opened a new avenue. In the past years, we and others have utilized Cas9-mediated genome editing to excise HIV-1 provirus in vitro, ex vivo and in vivo. One of challenges before clinical application is how to deliver effectively, specifically and safely the powerful genome editing machinery to HIV-1 latently infected cells. The objective of this proposal is to develop novel synthetic nanoparticle (NP) for the in vivo delivery of Cas9/sgRNA ribonucleoprotein (RNP) specifically to CD4 T cells, the most important HIV-1 latent cellular reservoir. We have recently developed a novel synthetic PEG-Morpholine copolymer (PEG-pMor) NP system for in vivo drug delivery in mouse model. Our preliminary data demonstrated the feasibility and efficiency of this PEG-pMor NP to deliver Cas9/sgRNA plasmid or RNP in multiple organs/tissues resulting in eradication of HIV-1 proviral DNA or host cellular genes in vivo. In this proposal, a novel CD4-specific designed ankyrin repeat protein (DARPin) peptide will be displayed on the surface of the PEG-pMor NP to achieve targeted delivery of Cas9/sgRNA RNP to human CD4 T cells in HIV-1-infected humanized mouse models.
In Aim I, we will develop and characterize CD4 T cell-targeting NP both in vitro and in vivo and determine the efficiency of CD4-specific DARPin-mediated Cas9/duplex sgRNA RNP to excise CCR5 gene in human primary T cells (in vitro) and humanized mouse model (in vivo).
In Aim II, we will determine the efficiency of CD4 T cell- targeting NP for in vivo delivery of Cas9/sgRNA RNP to excise HIV-1 proviral DNA.
In Aim III, we will assess the combinatory therapeutic potential of CD4 T cell-targeting NP in vivo delivery of Cas9/quadruplex sgRNA RNP (LTR1/GagD+CCR5-A/B) in blocking or delaying latent HIV-1 viral rebound in humanized mouse model. This high-reward proposal focuses on the screening of novel CD4 T cell-specific delivery of RNP genome editors to excise HIV-1 provirus and disable HIV-1 entry coreceptor CCR5 gene. The positive outcome will offer a novel tool to deliver Cas9/sgRNA RNP to CD4 T cells and/or other reservoir cells in vivo, and thus provide new avenues for the development of therapeutics to cure HIV-1.
HIV-1 infection has no effective vaccine and no known cure because of the dormant provirus in the infected T cells. This proposed research is relevant to public health, because the discovery of a novel CD4 T cell-specific in vivo delivery of Cas9/sgRNA ribonucleotide protein is ultimately expected to snip out HIV-1 provirus and knock out host CCR5 in HIV-1 latently infected T cells. Thus, the strategy to kill virus and save host cells in this proposal is relevant to the part of NIH's mission that helps develop novel therapeutics for the permanent cure of HIV/AIDS.
