Project Summary A comprehensive interdisciplinary approach proposed to support the Single Cell Opioid Responses in the Context of HIV (SCORCH) Program Expansion: CNS Data Generation for Chronic Opioid, Methamphetamine, and/or Cocaine Exposures RFA from the National Institute on Drug Abuse (NIDA). We will perform studies on the interplay of HIV pathogenesis and opioid abuse in the gold-standard SIV/nonhuman primate system, using single-cell RNA sequencing (scRNAseq) to assess individual cellular transcriptomes. This will give us obtain unparalleled insight into the viral and drug-induced effects on diverse cell types in brain in regions critical for HIV infection and opioid abuse. In addition, we will also focus on primary targets of HIV and drivers of neuropathogenesis, microglia and brain macrophages, using scRNAseq as well as single-cell Assay for Transposase-Accessible Chromatin sequencing (scATACseq) to gain insight into the epigenetic regulation of gene expression at the single cell level. These will be combined with state-of-the-art sensitive assays for virus in the brain. We will ensure our data adhere to the FAIR (Findable, Accessible, Interoperable, and Reusable) standards, and will work closely with other members of the SCORCH program to share and disseminate data to yield maximal advancement to the field. Our experiments are carefully designed to address the role of virus, drugs, and their interactions, as well as include the clinically relevant scenarios of those taking antiretrovirals to suppress virus, and those who do not. Our rigor and reproducibility are facilitated by our detailed power analysis with proper sample sizes, as well as our experimental design to match the standards of blocking, replication and randomization. The results from these studies will provide novel insights into the CNS effects of HIV and drug abuse.