A new Northwestern University study suggests that HIV persistence is shaped not only by the infected cells that harbor the virus, but also by the surrounding tissue environments that protect those cells from immune attack. In gut tissue from non-human primate models infected with simian immunodeficiency virus (SIV), researchers identified microenvironments bearing striking similarities to the immune-suppressive environments found around certain difficult-to-treat tumors. The findings offer a new explanation for why HIV reservoirs can survive for years during antiretroviral therapy and rapidly reignite infection when treatment is interrupted.
Published in Frontiers in Immunology, the study represents one of the first systematic comparisons of the tissue microenvironment surrounding persistent viral reservoirs with tumor microenvironments in the gut. Rather than focusing exclusively on the individual cells carrying viral genetic material, the researchers examined the broader cellular, molecular and structural context in which those cells exist. This shift in scale allowed them to investigate how neighboring immune cells, tissue signals and biological pathways may cooperate to create a sanctuary for viral persistence.
The researchers combined molecular imaging, immunoPET/CT-guided tissue mapping, spatial transcriptomics and machine-learning analyses to locate rare sites of viral persistence and characterize their surroundings. Spatial transcriptomics makes it possible to measure gene activity while preserving information about where individual cells are positioned within a tissue. Molecular imaging, by contrast, provides a map of anatomical and physiological features across the larger organ. Together, the approaches enabled the team to connect microscopic gene-expression patterns with the architecture of the gut and to determine which cell populations and signaling programs clustered around viral reservoirs.
The work was led by Eliana Crentsil, a graduate student working in the laboratories of Thomas J. Hope and Ramon Lorenzo-Redondo. Hope, a professor of cell and developmental biology and obstetrics and gynecology at Northwestern University Feinberg School of Medicine, contributed imaging expertise, while Lorenzo-Redondo, an assistant professor of medicine in the division of infectious diseases, led computational analyses of the tissue data. The complementary methods allowed the investigators to identify both the cellular composition of reservoir-associated sites and the communication networks linking those cells.
Most persistent HIV during suppressive treatment is found in tissues rather than circulating freely in the blood, and the gut is a particularly important reservoir site. The intestinal immune system contains large numbers of target cells and is extensively altered during HIV infection. By examining gut tissue directly, the Northwestern team observed that some long-lived reservoirs occupied environments resembling “cold” tumor microenvironments. These tumor regions are typically characterized by weak immune-cell infiltration, extensive tissue remodeling and molecular signals that prevent effective immune killing.
The comparison does not mean that HIV reservoirs are tumors or that HIV causes cancer through the same mechanism. Instead, it indicates that two very different biological problems may recruit overlapping strategies to evade immune surveillance. In both settings, local tissue conditions can limit the movement, activation or effectiveness of cytotoxic immune cells. The researchers found increased activity in pathways associated with extracellular-matrix remodeling and immune suppression around persistent viral reservoirs. Such changes may alter the physical structure of tissue while also generating chemical signals that discourage antiviral responses.
The study also identified important differences between reservoirs with distinct persistence patterns. Sites associated with longer-lived viral reservoirs displayed features more closely aligned with cold tumor environments, including reduced evidence of immune activity. Shorter-lived reservoirs more closely resembled “hot” tumor microenvironments, which generally contain greater numbers of immune cells capable of recognizing and destroying abnormal or infected cells. This contrast suggests that the probability of reservoir clearance may depend partly on whether the surrounding tissue permits immune cells to reach and eliminate infected targets.
Regulatory T cells emerged as central components of the communication networks surrounding viral reservoirs. These cells normally help prevent excessive inflammation and maintain immune tolerance, but their activity can also limit antiviral responses under certain conditions. By applying machine-learning methods to the spatial and molecular data, the researchers further identified human genes including KRT8, EPCAM and RRM2 as contributors to the tumor-like characteristics of persistent reservoir sites. The genes are involved in epithelial biology, cellular proliferation and tissue-state regulation, although their precise roles in maintaining HIV reservoirs will require additional study.
The findings could influence the design of future HIV cure strategies. Current approaches often aim to reactivate latent virus so that infected cells can be recognized and destroyed, or to strengthen immune responses against reservoir cells. The new results suggest that these interventions may be more effective if they are paired with methods that remodel the surrounding tissue environment. In principle, disrupting immune-suppressive signaling, changing tissue architecture or improving the access and function of antiviral immune cells could make reservoirs more vulnerable. However, the work was conducted in SIV-infected non-human primates, and the extent to which the same microenvironments operate in people living with HIV remains to be established. The study therefore provides a framework for investigating reservoir biology in human tissues rather than an immediately available cure.
Subject of Research: HIV and SIV viral reservoirs; tissue microenvironments; immune evasion; gut tissue; tumor microenvironment biology.
Article Title: A tissue microenvironment analogous to certain tumor microenvironments facilitates HIV persistence
News Publication Date: 4 August 2026
Web References: https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2026.1862864/full
References: Frontiers in Immunology, DOI: 10.3389/fimmu.2026.1862864
Keywords: HIV, human immunodeficiency virus, simian immunodeficiency virus, SIV, viral reservoirs, HIV persistence, gut tissue, viral microenvironment, tumor microenvironment, immune suppression, spatial transcriptomics, molecular imaging, machine learning, HIV cure research, cancer research
Tags: antiretroviral therapy resistancegut tissue viral persistenceHIV reservoir microenvironmentsimmune cell interactions in HIVimmune sanctuary for HIVmachine learning in viral tissue analysismolecular imaging for HIV researchsimian immunodeficiency virus modelsspatial transcriptomics in viral reservoirstissue microenvironment in HIVtumor microenvironment similaritiestumor-like immune suppression
