# Irreversible Proviral Silencing in Myeloid Cells

> **NIH NIH R21** · UNIVERSITY OF MIAMI SCHOOL OF MEDICINE · 2023 · $191,875

## Abstract

ABSTRACT:
 In the pursuit of strategies with which to cure HIV-1 infection, most of the attention has been on
mechanisms that govern HIV-1 persistence in CD4+ T cell reservoirs and on approaches to limit persistence in
those reservoirs. We recently provided evidence [1] that macrophages enable viral persistence in HIV-1-infected
individuals on effective ART. We showed that rebound viremia from individuals undergoing an analytic treatment
interruption (ATI) comprised highly macrophage-tropic viruses and we used a novel virion immunocapture
method to demonstrate that those macrophage-tropic viruses in post-ATI plasma had a myeloid cell origin.
Furthermore, Molecular Clock analysis indicated that macrophage-tropic viruses in plasma pre-dated the
treatment interruption as opposed to having been created during the treatment interruption interval.
 Given these lines of evidence that myeloid cells can serve as viral reservoirs under effective ART, we set
about establishing a latency model in primary macrophages. In the pursuit of this model of macrophage latency,
we observed that NF-kB inhibition, originally intended to promote synchronous latency, led to irreversible loss of
proviral competence- proviruses were refractory to latency reactivating agents (LRAs) even though host cell
functions remained intact. On the basis of these observations, we hypothesize that the provirus is epigenetically
modified under conditions where NF-kB is limiting and that sustained transcriptional activity is required to
counteract epigenetic silencing processes of the host cell. In this proposal, we will assess the mechanisms
governing loss of proviral competence.
 Aim 1: Assess correlates of proviral silencing in NF-kB-depleted macrophages. We will determine
the stage in the viral replication cycle at which proviruses are rendered inactive and, through heterokaryon
formation, whether dominant negative factors mediate irreversible proviral silencing by NF-kB inhibition. We will
examine whether inactive proviruses exhibit evidence of epigenetic modification and methylation and whether
inhibiting methylation can maintain proviral responsiveness to reactivation in the face of NF-kB inhibition.
 Aim 2: Examine whether the proviral silencing created under conditions of NF-kB inhibition can
be extended to infected CD4+ T cells from ART-suppressed subjects and to other primary macrophage
populations. We will assess whether NF-kB inhibition can irreversibly impede HIV-1 reactivation in CD4+ T cells
from individuals on effective ART and whether this proviral silencing can also be achieved in macrophages that
are physiologically representative of the major myeloid cell compartments including lung (alveolar macrophages),
liver (Kupffer cells), and Central Nervous System (microglia).
 If the proposed studies are successful, they will provide the rationale for in vivo studies using established
SHIV/macaque models of macrophage reservoirs and NF-kB antagonists currently in clinical use.

## Key facts

- **NIH application ID:** 10705469
- **Project number:** 1R21AI172772-01A1
- **Recipient organization:** UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
- **Principal Investigator:** Mario Stevenson
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $191,875
- **Award type:** 1
- **Project period:** 2023-08-02 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10705469

## Citation

> US National Institutes of Health, RePORTER application 10705469, Irreversible Proviral Silencing in Myeloid Cells (1R21AI172772-01A1). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10705469. Licensed CC0.

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