Current HIV Research - Volume 14, Issue 1, 2016

Background: Current HIV antiretroviral therapies potently suppress virus replication and prevent patients from progressing to AIDS but are unable to completely eliminate HIV due to the existence of dormant viral reservoirs which threaten to reemerge at anytime. Recently, genome-editing technologies that can recognize specific DNA sequences, including viral DNA, are being touted as promising tools for curing HIV, owing to their specificity, ease of use, and ability to be custom designed. Conclusion: Here, we introduce several novel strategies aimed at eradicating HIV proviruses with state-of-the-art genomeediting technologies and discuss perspectives of these approaches for curing HIV.

The role of antibody Fc-mediated effector functions in controlling or preventing infections by human immunodeficiency type 1 (HIV-1) and simian immunodeficiency (SIV) viruses has been recently highlighted in multiple studies. One of those effector functions, antibody-dependent cellular cytotoxicity (ADCC) was suggested as correlating with decreased HIV-1 acquisition risk in the recent Thai RV144 vaccine trial. RV144-elicited antibodies with potent ADCC activity were recently found to recognize HIV envelope (Env) epitopes exposed upon Env-CD4 interaction. However, HIV-1 efficiently limits the exposure of those epitopes by strongly downregulating CD4 by both Nef and Vpu accessory proteins, as well as indirectly preventing the accumulation of Env at the cell surface by Vpu-mediated BST-2 antagonism. These accessory proteins were thus proposed to play a critical role in decreasing the susceptibility of HIVinfected cells to elimination by ADCC. In this review we will summarize these recent findings and discuss the critical role that HIV-1 envelope glycoproteins conformation plays on ADCC responses, how these responses can be measured in the laboratory, the role of HIV-1-transmission on ADCC responses and how this knowledge can be used to develop new strategies aimed at targeting HIV-1-infected cells.

Background: Antiretroviral (ARV) drugs targeting retroviral enzymes have been extensively employed to treat HIV-1 infection. Drawbacks of this approach include cost, toxicity, and the eventual emergence of resistant strains that threaten prophylactic and/or therapeutic efficacy. Accordingly, efforts to develop next-generation ARV approaches are warranted, particularly if they can offer a higher threshold of resistance. We have previously shown that FLSC, a fusion protein containing gp120BAL and the D1 and D2 domains of human CD4, specifically binds CCR5, an important cellular co-receptor, and inhibits the entry of R5 HIV isolates. (FLSC) IgG1, a fusion of FLSC and the hinge-CH2-CH3 region of human IgG1, has an increased antiviral activity, likely due to the resultant bivalency. Methods: In this study, we show CCR5 reduction upon (FLSC) IgG1 treatment both by standard flow cytometry and visualized using a novel nanoparticle method. A β-lactamase virus-cell fusion assay was used to quantify (FLSC) IgG1 inhibition of HIV-1 entry into both cell lines and primary cells. Synergistic anti-viral activities of (FLSC) IgG1 and MVC in primary cells were evaluated by measuring supernatant p24 levels via ELISA and calculated using the MacSynergyTM II program. Results: We previously reported that treatment with the CCR5 small molecule antagonist Maraviroc (MVC) increased the apparent exposure of the (FLSC) IgG1 binding sites on CCR5, leading us to wonder if the two compounds used in combination might synergize in their anti-viral activity. Here we show that this is indeed the case. We demonstrate that fusion protein (FLSC) IgG1, strongly synergizes with the CCR5 antagonist Maraviroc to successfully inhibit both MVCsensitive and MVC-resistant R5 HIV-1. Conclusion: Observed synergy between (FLSC) IgG1 and MVC was high in both, cell lines and primary PBMCs. This has relevance for future in vivo studies. In addition, synergy occurred both with MVC-sensitive viruses and MVC-resistant viruses, partially restoring the inhibitory effect of MVC. These findings suggest that a combinatorial treatment based on these two compounds has potential merit and that future in vivo studies are warranted.

Objective: HIV lipodystrophy is characterised by abnormal adipose tissue distribution and metabolism, as a result of altered adipocyte function and gene expression. The protease inhibitor ritonavir is associated with the development of lipodystrophy. Quantifying changes in adipogenic gene expression in the presence of ritonavir may help to identify therapeutic targets for HIV lipodystrophy. Methods: Affymetrix Mouse Genome 430 2.0 oligonucleotide microarray was used to investigate gene expression in 3T3-L1 adipocytes treated with 20 μmol/l ritonavir or vehicle control (ethanol). Pparg, Adipoq, Retn and Il6 expression were validated by real time RT-PCR. Transcriptional signalling through PPAR-γ was investigated using a DNA-binding ELISA. Changes in adipocyte function were investigated through secreted adiponectin quantification using ELISA and Oil Red O staining for triglyceride storage. Results: Expression of 389 genes was altered by more than 5-fold in the presence of ritonavir (all P < 0.001). Gene ontology analysis revealed down-regulation of genes responsible for adipocyte triglyceride accumulation including complement factor D (Cfd; 238.42-fold), Cidec (73.75-fold) and Pparg (5.63-fold). Glucose transport genes were also down-regulated including Adipoq (24.42-fold) and Glut4 (13.36-fold), while Il6 was up-regulated (10.39-fold). PPAR-γ regulatory genes Cebpa (11.33-fold) and liver-X-receptor α (Nr1h3) were down-regulated. Changes in Pparg, Adipoq and Il6 were confirmed by RT-PCR. PPAR-γ binding to its nuclear consensus site, adiponectin secretion and triglyceride accumulation were all reduced by ritonavir. Conclusion: Ritonavir had a significant effect on expression of genes involved in adipocyte differentiation, lipid accumulation and glucose metabolism. Down-regulation of Pparg may be mediated by changes in Cebpa, Lcn2 and Nr1h3.

Introduction: Progressive multifocal leukoencephalopathy (PML) is a debilitating demyelinating disease of the CNS caused by the infection and destruction of glial cells by JC virus (JCV) and is an AIDS-defining disease. Infection with JCV is common and most people acquire antibodies early in life. After initial infection, JCV remains in an asymptomatic persistent state and can be detected by PCR in many tissues including brain. A major question in PML pathogenesis is how the virus reactivates from persistence in HIV-1/AIDS. Our studies with primary cultures of glial cells have implicated transcription factors NF-κB and NFAT4, which bind to a unique site in the JCV noncoding control region and stimulate viral gene expression. Furthermore, these transcription factors are controlled by pathways downstream of proinflammatory cytokines, e.g., TNF-α activates NF-κB and stimulates JCV transcription. Objectives: We hypothesize that HIV-1/PML initiation may involve reactivation of JCV by cytokine disturbances in the brain such as occur in HIV-1/AIDS. In this study, the objective was to evaluate HIV-1/PML clinical samples for expression of TNF-α and its receptors and subcellular localization of NF-κB p65 and NFAT4 compared to non-PML controls. Methods: We evaluated HIV-1/PML clinical samples and non-PML controls for expression of TNF-α and its receptors and subcellular localization of NF-κB p65 and NFAT4 using Western blot and immunohistochemistry. Results: Consistent with our hypothesis, compared to non-PML controls, HIV-1/PML tissue has high levels of TNF-α and TNFR1 expression and NF-κB and NFAT4 were preferentially localized to the nucleus. Conclusion: The involvement of TNF-α/NF-κB/NFAT4 signaling in JCV regulation that we reported from experiments in cultured human glial cells may be clinically relevant in PML.

Background: Tolerability, long-term toxicities and selection of resistant variants limit the use and efficacy of antiretroviral drugs in HIV-positive patients. Novel combinations are needed for mantaining long-term control of HIV replication; nevertheless scarse data are available on protease inhibitor-free dual antiretroviral therapies. Methods: A multi-centric retrospective study was conducted including HIV-1-positive patients on raltegravir/nevirapine dual regimens. Plasma concentrations were measured as therapeutic drug monitoring while a subset of patients underwent intensive 12-hour pharmacokinetic evaluation. Results: A total of 77 patients switching from successful regimens (76.6% male, median age 52 years) was included; 10 patients on raltegravir plus nevirapine once-daily while 67 subjects on twice-daily schedule. After a median follow-up of 32 months 69 patients (89.6%) were still successfully on treatment. Three patients discontinued for side effects (skin rash or hepatoxicity). Virological failure was observed in five patients (6.5%, 3 on once-daily schedule): in 4 patients (80%) resistance-associated mutations were observed (4 reverse transcriptase, 2 integrase). Triglycerides decreased in patients switching with lipid abnormalities (n=52) and estimated creatinine clearance increased in those with less than 60 ml/min (n=13). Median trough raltegravir and nevirapine concentrations were 83 ng/ml (32–227) and 5460 ng/ml (4037-7221); intensive 12-hours pharmacokinetic parameters (n=7) were similar to published data. Conclusion: Dual therapy with raltegravir/nevirapine in selected patients was highly effective over a 32-month follow up: virological failure was infrequent (6.5%), most common with once-daily schedule (60%) and often associated with the selection of resistance-associated mutations (80%). Twice-daily raltegravir plus nevirapine deserves further clinical evaluation as an NRTI- and PI-sparing strategy in selected patients.

Background: The association between abacavir use and increased risk of myocardial infarction has been heavily debated, but cohort studies and randomized trials have provided conflicting results. Aim of our study is to compare the effect of abacavir and tenofovir on the inflammation and endothelial activation markers. Methods: We performed an observational study of HIV-infected naïve patients starting tenofovir/emtricitabine (group A) or abacavir/lamivudine (group B) plus efavirenz. In the present analysis, we measured serum levels of high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), soluble vascular adhesion molecule-1 (VCAM-1), soluble intercellular adhesion molecule-1 (ICAM-1), E-selectin and P-selectin at baseline and during a 48-week follow-up. Results: As a whole, 118 patients (93 males; mean age ± SD of 42.8 ± 10.1 years) were enrolled: 61 in group A and 57 in group B. In group A at weeks 24 and 48 the mean concentrations of IL-6, TNF-α, ICAM-1, VCAM-1, E-selectin and Pselectin decreased significantly in comparison with respective baseline values. In group B at week 24 a significant increase in mean values of these markers was reported in comparison with group A, but after 48 weeks they significantly decreased in group B too and no significant differences between groups A and B were found. Conclusion: In our study, naïve patients starting tenofovir/emtricitabine or abacavir/lamivudine plus efavirenz showed after 48 weeks a significant and comparable decrease in serum concentrations of IL-6, TNF-α, ICAM-1, VCAM-1, Eselectin and P-selectin, while the mean level of hs-CRP did not change significantly in any group.

Introduction: Given the chronic nature of HIV infection and the need for life-long antiretroviral therapy (ART), maintaining long-term optimal adherence is an important strategy for maximizing treatment success. In order to understand better the dynamic nature of adherence behaviors in India where complex cultural and logistic features prevail, we assessed the patterns, trajectories and time-dependent predictors of adherence levels in relation to virological failure among individuals initiating first-line ART in India. Methods: Between July 2010 and August 2013, eligible ART-naïve HIV-infected individuals newly initiating first-line ART within the national program at three sites in southern India were enrolled and monitored for two years. ART included zidovudine/stavudine/tenofovir plus lamivudine plus nevirapine/efavirenz. Patients were assessed using clinical, laboratory and adherence parameters. Every three months, medication adherence was measured using pill count, and a structured questionnaire on adherence barriers was administered. Optimal adherence was defined as mean adherence ≥95%. Statistical analysis was performed using a bivariate and a multivariate model of all identified covariates. Adherence trends and determinants were modeled as rate ratios using generalized estimating equation analysis in a Poisson distribution. Results: A total of 599 eligible ART-naïve patients participated in the study, and contributed a total of 921 person-years of observation time. Women constituted 43% and mean CD4 count prior to initiating ART was 192 cells/mm3. Overall mean adherence among all patients was 95.4%. The proportion of patients optimally adherent was 75.6%. Predictors of optimal adherence included older age (≥40 years), high school-level education and beyond, lower drug toxicity-related ART interruption, full disclosure, sense of satisfaction with one’s own health and patient’s perception of having good access to health-care services. Adherence was inversely proportional to virological failure (IRR 0.55, 95%CI 0.44-0.69 p<0.001). Drug toxicity and stigma-related barriers were significantly associated with virological failure, while forgetfulness was not associated with virological failure. Conclusion: Our study highlights the overall high level of medication adherence among individuals initiating ART within the Indian national program. Primary factors contributing towards poor adherence and subsequent virological failure in the proportion of individuals with poor adherence included drug toxicity, perceived stigma and poor access to health care services. Strategies that may contribute towards improved adherence include minimizing drug interruptions for medical reasons, use of newer ART regimens with better safety profiles and increasing access with more link ART centers that decentralize ART dispensing systems to individuals.