A Tissue Microenvironment Analogous to Certain Tumor Microenvironments Facilitates HIV Persistence

The HIV reservoir that establishes early upon infection and persists in tissues remains the primary barrier to a functional cure. While progress has been made to study the reservoir in blood compartments and specific cell types, knowledge gaps remain on the tissue microenvironment that facilitates persistence. The development of a novel immunoPET/CT-guided spatial transcriptomics pipeline has enabled the localization of foci of viral infection in tissues, rare events that are challenging to sample. Prior studies leveraging the pipeline have characterized the viral microenvironment (VME) gene signatures, cell types and interactions, and host transcriptome gene drivers of viral persistence. Detailed characterization of the VME revealed multiple shared features with certain tumor microenvironments (TMEs), suggesting shared immunoregulatory and survival mechanisms. In this study, we apply the immunoPET/CT-guided spatial transcriptomics pipeline in the SIVmac239/rhesus macaque model to define immune mechanisms underlying persistent versus transient HIV/SIV reservoirs. We utilize a systematic approach to highlight correlates between the VME and TME transcriptional programs, gene pathways, local tissue neighborhoods, cell-cell interactions, and host transcriptomic drivers. Analysis of broad transcriptional programs revealed SIV-localized spatial enrichment of genes associated with multiple cancer subtypes. The persistent reservoir was characterized by gene pathways of "cold" TMEs (e.g., epithelial to mesenchymal transition, TGF{beta} activation) whereas the transient reservoir was comparable to "hot" TMEs with cytotoxic immune activation. Cell-cell interaction analysis identified regulatory T cells as a key mediator of interactions in both persistent and transient reservoirs. Machine learning identified KRT8, EPCAM, and RRM2, genes with known roles in mediating carcinogenesis, among the top host transcriptomic drivers of the TME phenotype of the persistent VME. Collectively, the findings of this study provide novel and transformative insights on key mechanisms of HIV/SIV persistence and reveal potential targets for immunotherapeutic strategies aimed at reservoir disruption or clearance towards a functional HIV cure.