Elimination of HIV-1-Infected Primary T Cell Reservoirs in an In Vitro Model of Latency.

Stephen A Rawlings,Derya Unutmaz,Lina Kozhaya,Victor J Torres,Francis Alonzo,Yuntao Wu

doi:10.1371/journal.pone.0126917

Abstract

Establishment of long-lived cellular reservoirs of HIV-1 represents a major therapeutic challenge to virus eradication. In this study, we utilized a human primary cell model of HIV-1 latency to evaluate the requirements for efficient virus reactivation from, and the selective elimination of, latently infected human T cells. Ectopic expression of BCL2 supported the replication and spread of R5-tropic HIV-1 in activated CD4+ T cells. After IL-2 withdrawal, the HIV-1-infected T cells survived as resting cells for several months. Unexpectedly, these resting T cells continue to produce detectable levels of infectious virus, albeit at a lower frequency than cells maintained in IL-2. In the presence of HIV-1 inhibitors, reactivation of the resting T cells with γc-cytokines and allogeneic dendritic cells completely extinguished HIV-1 infectivity. We also evaluated the ability of the bacterial LukED cytotoxin to target and kill CCR5-expressing cells. After γc-cytokine stimulation, LukED treatment eliminated both HIV-1-infected resting cells and the non-infected CCR5+ cells. Importantly, complete clearance of in vitro HIV-1 reservoirs by LukED required a lower threshold of cytokine signals relative to HIV-1 inhibitors. Thus, the primary T cell-based HIV-1 latency model could facilitate the development of novel agents and therapeutic strategies that could effectively eradicate HIV-1.

Highlights

Active antiretroviral therapy (HAART) reduces HIV-1 viremia and leads to substantial reductions in HIV-related morbidity and mortality
In order to create a population of primary CD4+ T cells that could be infected with HIV-1 and withstand cytokine withdrawal, we activated total CD4+ T cells from healthy, uninfected individuals with αCD3/αCD28 beads and transduced them with a BCL2-encoding vector
We identified a novel approach to eliminate the HIV-1 reservoir by targeting and removing both latently infected and uninfected, CCR5+ target cells using the recently identified staphylococcal toxin, CCR5-binding leukotoxin ED (LukED)

Summary

Introduction

Active antiretroviral therapy (HAART) reduces HIV-1 viremia and leads to substantial reductions in HIV-related morbidity and mortality. Even after prolonged therapy and undetectable viremia, discontinuation or interruption of treatment can cause rapid rebound of HIV-1 and progression to AIDS [1]. This is due to a long-lived reservoir for the virus that takes advantage of the dynamics of immunological memory and does not naturally decay at a rate that could lead to drug independence in a normal lifespan [2, 3]. T cells infected as they transition from an activated to resting state are recognized as a major source of the HIV-1 reservoir [4, 5] These quiescent, infected T cells are likely protected from cytopathic effects of PLOS ONE | DOI:10.1371/journal.pone.0126917. These quiescent, infected T cells are likely protected from cytopathic effects of PLOS ONE | DOI:10.1371/journal.pone.0126917 May 19, 2015

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