Project Summary/Abstract: Newer insights into long-term natural control of HIV infection in the absence of ART will inform efforts to induce a functional cure or “remission.” Recent work has identified a subset of HIV elite controllers (EC) who are considered “exceptional” (EEC) with decades of virologic control without immunologic decline. Multiple mechanisms likely contribute to control in EECs, including a potent and sustained CD8+ T cell response. However, it is unclear whether EECs can maintain this status indefinitely, whether they have any ongoing viral activity and benefit from initiation of ART (or are harmed by withdrawal of ART), or whether they spontaneously cleared viral reservoirs. Whether such individuals may represent a true model of durable HIV control or, in some cases, a functional cure are important questions needing further investigation. Leveraging the largest elite controller cohort in the USA, the UCSF SCOPE cohort, our recent work focused on the question: is there a subset of ECs that might serve as a model for long-term ART-free HIV remission? Using the new intact proviral DNA assay (IPDA) to detect intact proviruses as well as sensitive antibody and T-cell immune-assays, we identified a small subset of 21 exceptional ECs with ultra-low reservoir size. Recent analyses using a combination of IPDA and FLIP-seq suggested that some ECs have ultralow levels of intact proviruses existing in a deeply latent state making their detection difficult. Therefore, novel virological assays to detect ultralow levels of latent HIV and immunological analyses to evaluate the role of CD8+ T cell control need to be employed to further our understanding of EECs. Towards this goal, we propose to employ our new ultrasensitive in vivo humanized mouse viral outgrowth assay (hmVOA) model for latent viral detection. This model also provides a unique in vivo setting to examine the role of immune control since CD4+ T cells from the EEC can be tested for viral outgrowth in the presence or absence of autologous CD8+ T cells believed to mediate control which is otherwise not possible to evaluate in a human setting. While full comprehension of EECs is a complex undertaking, here we propose to start with simpler initial goals to: 1. Determine whether intact HIV can be recovered (via viral outgrowth) from exceptional elite controllers not currently on ART and elite controllers on long-term ART using the humanized mouse viral outgrowth (hmVOA) assay 2. Ascertain if the predominant viral control in EEC is indeed mediated by CD8+ T cells and assess if this control can also provide resistance to a potential new HIV exposure (superinfection) in vivo. Results from here will help in furthering our understanding of the latent virus and the role of strong cell-mediated virus control in EECs.

Project Narrative: Study of a population of natural HIV controllers is likely to provide clues as to how the body counters infection effectively using its own resources. The goal of this proposal is to evaluate exceptional elite controllers (EEC) of HIV infection for the presence of latent virus and look at the role of CD8+ T cell mediated immunological control using a humanized mouse-based animal model. Cord-blood derived hematopoietic stem cells (HSC) will be used to prepare hu-HSC mice for detecting latent viral outgrowth.