Summary Studies have revealed the exciting promise of CRIPSR/Cas genome editing to excise provirus for HIV cure. However, a major barrier to their clinical application is how to deliver it to latently infected cells effectively and specifically in vivo. The overall objective of this proposal is to close this gap by developing a new lentivirus-like particle fusogenic resicle (LVLP-R) that will specifically deliver multiplexed Cas12a ribonucleoprotein (RNP) and mRNA via MS2 coat protein (MCP) to CD4-expressing cells in vivo for excision of HIV proviruses and coreceptor CCR5. This CD4-targeted LVLP-R (LVLP-R-CD4) will deliver Cas12a protein/mRNA and multiplexed guide RNAs (gRNAs) with an increased excision efficiency and reduced off-target potential due to lack of lentiviral reverse transcription and integration. We hypothesize that LVLP-R-CD4 with Cas12a RNP/mRNA can simultaneously excise HIV proviral DNA and CCR5 in vivo. This hypothesis is supported by our preliminary data and pre-existing reports on successful RNP/mRNA LVLP delivery and multiplex genome editing in vivo. In Aim I, we will optimize our established VSVG-pseudotyped LVLP-R (LVLP-R-V) delivery of Cas12a RNP/mRNA both in vitro and in vivo for HIV proviral and CCR5 excision. In Aim II, we will develop and optimize DARPin or HIV Env-mediated LVLP-R-CD4 that efficiently delivers Cas12a RNP/mRNA to human CD4 T cells for genome editing in vitro and in vivo. In Aim III, we will evaluate HIV proviral and CCR5 excision for an HIV cure using LVLP-R-CD4 delivery of multiplexed Cas12a RNP/mRNA in HIV-infected ART-suppressed humanized-BLT mice. We focus on targeting CD4 T cells as our primary test platform because (1) our group was the first to apply CRISPR/Cas genome editing to excise HIV proviral DNA in T cell; (2) CD4 T cells are the major latent reservoir cells of HIV infection; and (3) the research team in this proposal has extensive expertise in studying lentiviral delivery and HIV infection of CD4 T cells using various approaches, including the humanized-mouse model. This high-reward proposal will explore a new LVLP-R-CD4 delivery of advantaged LbCas12a RNP/mRNA to CD4 cells and excise HIV provirus and CCR5 as a novel cure strategy. Completion of the proposed studies will offer a novel tool to deliver genome editors to CD4 cells in vivo and may provide a new gene therapy approach to HIV and other T cell-related diseases.