Cellular metabolism governs the susceptibility of CD4 T cells to HIV-1 infection. Multiple early post-fusion steps of HIV-1 replication are restricted in resting peripheral blood CD4 T cells; however, molecular mechanisms that underlie metabolic control of these steps remain undefined. Here, we show that mTOR activity following T cell stimulatory signals overcomes metabolic restrictions in these cells by enabling the expansion of dNTPs to fuel HIV-1 reverse transcription (RT), as well as increasing acetyl-CoA to stabilize microtubules that transport RT products. We find that catalytic mTOR inhibition diminishes the expansion of pools of both of these metabolites by limiting glucose and glutamine utilization in several pathways, thereby suppressing HIV-1 infection. We demonstrate how mTOR-coordinated biosyntheses enable the early steps of HIV-1 replication, add metabolic mechanisms by which mTOR inhibitors block HIV-1, and identify some metabolic modules downstream of mTOR as druggable targets for HIV-1 inhibition.

Immunodeficiency does not progress for prolonged periods in some HLA B57- and/or B27-positive subjects with human immunodeficiency virus type 1 (HIV) infection, even in the absence of antiretroviral therapy (ART). These “controllers” have fewer HIV provirus-containing peripheral blood mononuclear cells than “non-controller” subjects, but lymphocytes that harbor latent proviruses were not specifically examined in studies to date. Provirus levels in resting memory cells that can serve as latent reservoirs of HIV in blood were compared here between controllers and ART-suppressed non-controllers. APOBEC3G (A3G), a cellular factor that blocks provirus formation at multiple steps if not antagonized by HIV virion infectivity factor (Vif), was also studied. HLA-linked HIV control was associated with less provirus and more A3G protein in resting CD4+ T central memory (Tcm) and effector memory (Tem) lymphocytes (provirus: p = 0.01 for Tcm and p = 0.02 for Tem; A3G: p = 0.02 for Tcm and p = 0.02 for Tem). Resting memory T cells with the highest A3G protein levels (>0.5 RLU per unit of actin) had the lowest levels of provirus (<1,000 copies of DNA per million cells) in vivo (p = 0.03, Fisher's exact test). Using two different experimental approaches, Vif-positive viruses with more A3G were found to have decreased virion infectivity ex vivo. These results raise the hypothesis that HIV control is associated with increased cellular A3G that may be packaged into Vif-positive virions to add that mode of inhibition of provirus formation to previously described adaptive immune mechanisms for HIV control.

Objective: To evaluate four strategies for monitoring plasma HIV RNA levels and/or resistance genotypes to decide when to change antiretroviral therapy. The strategies include: (i) 1997 guidelines recommending a therapy switch when plasma RNA exceeds a threshold level; (ii) a viral load policy, using a fixed increase in viral load as the trigger; (iii) a genotype policy, requiring a smaller viral rebound than (ii) and detection of genotypic resistance before switching; and (iv) a proactive policy, switching drug regimens at a predetermined time if viral load has not rebounded. Design and setting: A Monte Carlo simulation tracks patients’ viral loads and presence of opportunistic infection during therapy. The model uses clinical and virological data and statistical variation in patient parameters for the evaluation of therapeutic strategies. Main outcome measures: To determine which strategies minimize viral rebound detection delay while maintaining a low (prespecified) probability of switching therapy before rebound. Results: 1997 Guidelines and the viral load policy create lengthy delays in detection of rebound, particularly when patients are drug-naive and the detection limit of the viral load assay is 500 copies/ml. A detection limit of 20 copies/ml decreases this delay substantially. Genotyping achieves only minor additional delay reductions. Of the strategies tested, the proactive policy leads to the shortest delays. Conclusions: This model indicates that prolonged periods may be required for viral load to rebound to detectable levels following prolonged suppression. Proactive switching produces the best outcome in our model because it may reduce the duration of viral replication under pressure of a failing regimen before detection of viral rebound. This strategy should be evaluated in clinical trials.

Translocated lipopolysaccharide (LPS) activates monocytes via TLR4 and is hypothesized to increase cardiovascular disease risk in persons living with HIV. We tested whether mTOR activity supports LPS-stimulated monocyte production of pro-inflammatory cytokines and tissue factor (TF), as it propels the inflammatory response in several immune cell types besides monocytes. However, multi-omics analyses here demonstrate that mTOR activates a metabolic pathway that limits abundance of these gene products in monocytes. Treatment of primary human monocytes with catalytic mTOR inhibitors (mTORi) increased LPS-induced polyfunctional responses, including production of IL-1β, IL-6, and the pro-coagulant, TF. NF-κB-driven transcriptional activity is enhanced with LPS stimulation after mTORi treatment to increase expression ofF3(TF). Moreover, intracellular NAD⁺availability is restricted due to decreased salvage pathway synthesis. These results document mTOR-mediated restraint of the LPS-induced transcriptional response in monocytes and a metabolic mechanism informing strategies to reverse enhanced risk of coagulopathy in pro-inflammatory states.

The bisheteroarylpiperazine nonnucleoside reverse transcriptase (RT) inhibitor atevirdine effectively inhibits human immunodeficiency virus type 1 (HIV-1) in vitro. Clinical isolates with a wide range of 50% inhibitory concentrations (IC₅₀s) of zidovudine (IC₅₀ , 0.003 to >2.0 µM) and didanosine (IC₅₀ , 0.02 to > 10.0µM) were inhibited by atevirdine (median IC₅₀ , 0.74µM; range, 0.06-1.60). Cross-resistance to atevirdine in zidovudine- or didanosine-resistant isolates was not observed. Combinations ofatevirdine and zidovudine were highly synergistic against zidovudineresistant clinical isolates of HIV-1. By contrast, these combinations were mostly additive when tested against zidovudine-susceptible isolates. Combinations of atevirdine and didanosine were additive in their effects against both didanosine-susceptible and -resistant isolates. These data suggest that the interaction of atevirdine with HIV-1 RT is different than that of other nonnucleoside RT inhibitors and that combinations of atevirdine and zidovudine may be useful in patients with AIDS who have initially received monotherapy with zidovudine.