Persistence of replication-competent HIV in both memory and naive CD4 T cell subsets in patients on prolonged and effective HAART

114

111

In this study, we examined the peripheral blood (PB) central memory (T CM ) CD4؉ T cell subsets designated peripheral T follicular helper cells (pTfh cells) and non-pTfh cells to assess HIV permissiveness and persistence. Purified pTfh and non-pTfh cells from healthy HIV-negative donors were tested for HIV permissiveness using green fluorescent protein (GFP)-expressing HIV-1NL4-3/Ba-L, followed by viral reactivation using beads coated with anti-CD3/anti-CD28 monoclonal antibodies. The role of pTfh cells in HIV persistence was analyzed in 12 chronically HIV-1 infected patients before and 48 weeks after initiation of raltegravir-containing combination antiretroviral therapy (cART). Total cellular HIV-1 DNA and episomes containing two copies of the viral long terminal repeat (2LTR circles) were analyzed in using droplet digital PCR in the purified pTfh and non-pTfh cells.

Section: Discussionmentioning

confidence: 99%

Peripheral T Follicular Helper Cells Are the Major HIV Reservoir within Central Memory CD4 T Cells in Peripheral Blood from Chronically HIV-Infected Individuals on Combination Antiretroviral Therapy

Pallikkuth

Sharkey

Babič

et al. 2016

114

111

“…Interestingly, HIV-1 Nef protein induces Thelper-cell depletion in an in vivo transgenic mouse model (14-17, 21, 24, 25, 33, 59), although it is not clear whether (i) this effect is due to intracellular or extracellular Nef protein or (ii) this effect is a developmental consequence of constitutive expression of the transgene or a model for Nef effect in HIV infection. Further, in patients receiving highly active combination antiretroviral therapy and with undetectable plasma viral RNA levels, several studies have shown (i) a stable pool of T cells harboring latent replication-competent virus (39) and (ii) detectable levels of early viral spliced mRNA in the PBMCs (67). One can speculate that, in light of the accumulated evidence concerning extracellular Nef, even in this scenario, expression of low levels of Nef could cause continued, albeit slower, depletion of T cells.…”

Section: Discussionmentioning

confidence: 99%

Extracellular Nef Protein Targets CD4⁺T Cells for Apoptosis by Interacting with CXCR4 Surface Receptors

James¹,

Huang²,

Khan³

et al. 2004

115

The effects of soluble Nef protein on CD4؉ T cells were examined. CD4 ؉ -T-cell cultures exposed to soluble Nef were analyzed for apoptosis by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling and hallmarks of apoptosis including cytoplasmic shrinkage, nuclear fragmentation, DNA laddering, and caspase activation. We observed dose-and time-dependent inductions of apoptosis. DNA laddering and activated caspase 3 were also evident. Cells treated with Nef/protein kinase inhibitor complexes were protected from Nef-induced apoptosis, suggesting possible roles for protein kinases in the apoptosis pathway. Similarly, cells treated with Nef/anti-Nef antibody complexes were protected from Nef-induced apoptosis. The cellular receptor responsible for Nef-induced apoptosis was identified through antibody-and ligand-blocking experiments as a receptor commonly involved in viral entry. CXCR4 antibodies, as well as the endogenous ligand SDF-1␣, were effective in blocking Nef-induced apoptosis, while CCR5 and CD4 antibodies were ineffective. Moreover, a CXCR4-deficient cell line, MDA-MB-468, which was resistant to Nef-induced apoptosis, became sensitive upon transfection with a CXCR4-expressing vector. This study suggests that extracellular Nef protein could contribute to the decline of CD4 counts prior to and during the onset of AIDS in patients with human immunodeficiency virus type 1 infections.

“…This finding indicates that quantification of viral DNA alone is not necessarily predictive of the size of the inducible latent reservoir and suggests caution in labeling a cellular reservoir of latent HIV-1 as "major" based solely on the frequency of infection. In addition to the memory CD4 ϩ T cell subsets, HIV-1 DNA is almost always detected in T N cells in both viremic and suppressed individuals, although with a much lower frequency than in the T CM and T TM compartments (6,7,(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). Interestingly, in 2013 Saez-Cirion et al reported that in some HIV-1-infected individuals who received ART within 10 weeks of primary infection, viremia could be controlled for at least 24 months posttreatment interruption (8).…”

Section: A Latent Hiv-1 Reservoir Is Established In Resting Cd4mentioning

confidence: 99%

Establishment and Reversal of HIV-1 Latency in Naive and Central Memory CD4⁺T CellsIn Vitro

Zerbato

Serrao

Lenzi

et al. 2016

The latent HIV-1 reservoir primarily resides in resting CD4؉ T cells which are a heterogeneous population composed of both naive (T N ) and memory cells. In HIV-1-infected individuals, viral DNA has been detected in both naive and memory CD4 ؉ T cell subsets although the frequency of HIV-1 DNA is typically higher in memory cells, particularly in the central memory (T CM ) cell subset. T N and T CM cells are distinct cell populations distinguished by many phenotypic and physiological differences. In this study, we used a primary cell model of HIV-1 latency that utilizes direct infection of highly purified T N and T CM cells to address differences in the establishment and reversal of HIV-1 latency. Consistent with what is seen in vivo, we found that HIV-1 infected T N cells less efficiently than T CM cells. However, when the infected T N cells were treated with latency-reversing agents, including anti-CD3/CD28 antibodies, phorbol myristate acetate/phytohemagglutinin, and prostratin, as much (if not more) extracellular virion-associated HIV-1 RNA was produced per infected T N cell as per infected T CM cell. There were no major differences in the genomic distribution of HIV-1 integration sites between T N and T CM cells that accounted for these observed differences. We observed decay of the latent HIV-1 cells in both T cell subsets after exposure to each of the latency-reversing agents. Collectively, these data highlight significant differences in the establishment and reversal of HIV-1 latency in T N and T CM CD4؉ T cells and suggest that each subset should be independently studied in preclinical and clinical studies. IMPORTANCE The latent HIV-1 reservoir is frequently described as residing within resting memory CD4؉ T cells. This is largely due to the consistent finding that memory CD4 ؉ T cells, specifically the central (T CM )