Stimulation of HIV-1-specific cytolytic T lymphocytes facilitates elimination of latent viral reservoir after virus reactivation.

Highly active antiretroviral therapy (HAART) suppresses HIV-1 replication but cannot eliminate the virus because HIV-1 establishes latent infection. Interruption of HAART leads to a rapid rebound of viremia, so life-long treatment is required. Efforts to purge the latent reservoir have focused on reactivating latent proviruses without inducing global T cell activation. However, the killing of the infected cells after virus reactivation, which is essential for elimination of the reservoir, has not been assessed. Here we show that after reversal of latency in an in vitro model, infected resting CD4(+) T cells survived despite viral cytopathic effects, even in the presence of autologous cytolytic T lymphocytes (CTLs) from most patients on HAART. Antigen-specific stimulation of patient CTLs led to efficient killing of infected cells. These results demonstrate that stimulating HIV-1-specific CTLs prior to reactivating latent HIV-1 may be essential for successful eradication efforts and should be considered in future clinical trials.

Novel structurally related compounds reactivate latent HIV-1 in a bcl-2-transduced primary CD4+ T cell model without inducing global T cell activation.

BACKGROUND: The latent reservoir of HIV-1 in resting memory CD4+ T cells is a major barrier to curing HIV-1 infection. Eradication strategies involve reactivation of this latent reservoir; however, agents that reactivate latent HIV-1 through non-specific T cell activation are toxic. METHODS: Using latently infected Bcl-2-transduced primary CD4+ T cells, we screened the MicroSource Spectrum library for compounds that reactivate latent HIV-1 without global T cell activation. Based on the structures of the initial hits, we assembled ∼50 derivatives from commercial sources and mostly by synthesis. The dose-response relationships of these derivatives were established in a primary cell model. Activities were confirmed with another model of latency (J-Lat). Cellular toxicity and cytokine secretion were tested using freshly isolated human CD4+ T cells. RESULTS: We identified two classes of quinolines that reactivate latent HIV-1. Class I compounds are the Mannich adducts of 5-chloroquinolin-8-ol. Class II compounds are quinolin-8-yl carbamates. Most EC(50) values were in the 0.5-10 µM range. HIV-1 reactivation ranged from 25% to 70% for anti-CD3+ anti-CD28 co-stimulation. All quinolin-8-ol derivatives that reactivate latent HIV-1 follow Lipinski's Rule of Five, and most follow the stricter rule of three for leads. After 48 h of treatment, none of the analogues induced detectable cytokine secretion in primary resting CD4+ T cells. CONCLUSIONS: We discovered a group of quinolin-8-ol derivatives that can induce latent HIV-1 in a primary cell model without causing global T cell activation. This work expands the number of latency-reversing agents and provides new possible scaffolds for further drug development research.

Influence of host gene transcription level and orientation on HIV-1 latency in a primary-cell model.

Human immunodeficiency virus type 1 (HIV-1) establishes a latent reservoir in resting memory CD4(+) T cells. This latent reservoir is a major barrier to the eradication of HIV-1 in infected individuals and is not affected by highly active antiretroviral therapy (HAART). Reactivation of latent HIV-1 is a possible strategy for elimination of this reservoir. The mechanisms with which latency is maintained are unclear. In the analysis of the regulation of HIV-1 gene expression, it is important to consider the nature of HIV-1 integration sites. In this study, we analyzed the integration and transcription of latent HIV-1 in a primary CD4(+) T cell model of latency. The majority of integration sites in latently infected cells were in introns of transcription units. Serial analysis of gene expression (SAGE) demonstrated that more than 90% of those host genes harboring a latent integrated provirus were transcriptionally active, mostly at high levels. For latently infected cells, we observed a modest preference for integration in the same transcriptional orientation as the host gene (63.8% versus 36.2%). In contrast, this orientation preference was not observed in acutely infected or persistently infected cells. These results suggest that transcriptional interference may be one of the important factors in the establishment and maintenance of HIV-1 latency. Our findings suggest that disrupting the negative control of HIV-1 transcription by upstream host promoters could facilitate the reactivation of latent HIV-1 in some resting CD4(+) T cells.

Disulfiram reactivates latent HIV-1 in a Bcl-2-transduced primary CD4+ T cell model without inducing global T cell activation.

Highly active antiretroviral therapy (HAART) can reduce plasma HIV-1 levels to below the detection limit. However, due to the latent reservoir in resting CD4(+) cells, HAART is not curative. Elimination of this reservoir is critical to curing HIV-1 infection. Agents that reactivate latent HIV-1 through nonspecific T cell activation are toxic. Here we demonstrate in a primary CD4(+) T cell model that the FDA-approved drug disulfiram reactivates latent HIV-1 without global T cell activation. The extent to which disulfiram reactivates latent HIV-1 in patient cells is unclear, but the drug alone or in combination may be useful in future eradication strategies.