Reports indicate that myeloid and plasmacytoid dendritic cells (mDCs and pDCs), which are key effector cells in host innate immune responses, can be infected with HIV-1 and are reduced in number and function during the chronic phase of HIV disease. Furthermore, it was recently demonstrated that a sustained loss of mDCs and pDCs occurs in SIV-infected macaques. Since loss of functional DC populations might impair innate immune responses to opportunistic microorganisms and neoplastic cells, we explored whether inoculation of naive and SIV- or SHIV-infected pigtailed macaques with the hematopoietic cytokine FLT3-ligand (FLT3-L) would expand the number of mDCs and pDCs in vivo. After the macaques received supraphysiologic doses of FLT3-L, mDCs, pDCs, and monocytes increased up to 45-fold in blood, lymph nodes, and bone marrow (BM), with DC expansion in the BM preceding mobilization in blood and lymphoid tissues. FLT3-L also increased serum levels of IL-12, at least transiently, and elicited higher surface expression of HLA-DR and the activation markers CD25 and CD69 on NK and T cells. During and after treatment of infected animals, APCs increased in number and were activated; however, CD4+ T cell numbers, virion RNA, and anti-SIV/SHIV antibody titers remained relatively stable, suggesting that FLT3-L might be a safe modality to expand DC populations and provide therapeutic benefit during chronic lentivirus infections.
The high rate of HIV-1 mutation and the frequent sexual transmission highlight the need for novel therapeutic modalities with broad activity against both CXCR4 (X4) and CCR5 (R5)-tropic viruses. We investigated a large number of natural products, and from Sargassum fusiforme we isolated and identified palmitic acid (PA) as a natural small bioactive molecule with activity against HIV-1 infection. Treatment with 100 μM PA inhibited both X4 and R5 independent infection in the T cell line up to 70%. Treatment with 22 μM PA inhibited X4 infection in primary peripheral blood lymphocytes (PBL) up to 95% and 100 μM PA inhibited R5 infection in primary macrophages by over 90%. Inhibition of infection was concentration dependent, and cell viability for all treatments tested remained above 80%, similar to treatment with 10−6 M nucleoside analogue 2′, 3′-dideoxycytidine (ddC). Micromolar PA concentrations also inhibited cell-to-cell fusion and specific virus-to-cell fusion up to 62%. PA treatment did not result in internalization of the cell surface CD4 receptor or lipid raft disruption, and it did not inhibit intracellular virus replication. PA directly inhibited gp120-CD4 complex formation in a dose-dependent manner. We used fluorescence spectroscopy to determine that PA binds to the CD4 receptor with Kd ∼1.5 ± 0.2 μM, and we used one-dimensional saturation transfer difference NMR (STD-NMR) to determined that the PA binding epitope for CD4 consists of the hydrophobic methyl and methelene groups located away from the PA carboxyl terminal, which blocks efficient gp120-CD4 attachment. These findings introduce a novel class of antiviral compound that binds directly to the CD4 receptor, blocking HIV-1 entry and infection. Understanding the structure–affinity relationship (SAR) between PA and CD4 should lead to the development of PA analogs with greater potency against HIV-1 entry.
Short-course zidovudine (ZDV) with or without a single dose of nevirapine (sdNVP) is widely used to prevent mother-to-child HIV transmission (PMTCT). However, more data on viral load in breast milk following pMTCT regimens are needed. In a randomized PMTCT study in Botswana, in which half of the women received sdNVP in labor, stored samples from mothers assigned to breastfeed were analyzed for HIV-1 RNA in breast milk supernatant. A total of 527 samples from 282 women, collected at delivery, 2 weeks, 2 months, and 5 months postpartum were available for testing. Cell-free breast milk HIV-1 RNA was detectable (>40 copies/ml) in 44.8% (236/527) of samples analyzed. Women randomized to sdNVP + ZDV were more likely to have undetectable breast milk viral loads at 2 weeks postpartum compared with those who received ZDV alone (67.8% vs. 38.5%, p = 0.002). By 2 months postpartum the difference between study arms disappeared, and 43.8% of women who received sdNVP + ZDV had undetectable HIV-1 RNA compared to 53.8% of the ZDV alone group (p = 0.19) and 60.5% vs. 64.5%, respectively, at month 5 (p = 0.61.) The addition of sdNVP to antenatal short-course AZT resulted in significantly reduced breast milk viral loads at 2 weeks postpartum suggesting a reduced risk of MTCT during the early postpartum period. However, viral loads in both study arms were comparable at 2 and 5 months postpartum, suggesting that the receipt of sdNVP in labor may defer rather than blunt the postpartum viral load rebound seen in breast milk after the discontinuation of ZDV.
The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) infections, in particular with Panton-Valentine leukocidin (PVL)-positive strains, has not been well characterized in children and young adults with HIV infection. It is not known if PVL-positive strains of MRSA cause an increased morbidity in this population compared to PVL-negative strains. The purpose of this study was to retrospectively analyze the epidemiology of PVL-positive and PVL-negative MRSA infections in children and young adults with HIV from 2000 to 2007. Molecular typing was performed by polymerase chain reaction (PCR) for detection of the PVL genes. Staphylococcus Cassette Chromosome (SCC) mec and spa typing were performed on all PVL-positive isolates. The number of HIV patients with MRSA infection increased significantly between 2000 and 2007 (p = 0.0015). Twenty seven (87%) of the 31 MRSA isolates were from skin and soft tissue infections (SSTI). Clindamycin resistance was observed in 19% of the MRSA isolates. PVL-positive isolates bearing the type IV SCC mec element comprised 16 of 31 (52%) MRSA isolates. All the PVL-positive isolates belonged to the USA300 pulsed-field type. There was no difference in the mean CD4 count and HIV viral load between patients with PVL-positive and PVL-negative MRSA infections. PVL-positive MRSA infections were associated with more SSTI (p = 0.043) but not with increased morbidity or a higher risk of complications compared to PVL-negative MRSA infections in children and young adults with HIV.
Pathogenic microorganisms encode proteins that antagonize specific aspects of innate or adaptive immunity. Just as the study of the HIV-1 accessory protein Vif led to the identification of cellular cytidine deaminases as host defense proteins, the study of HIV-1 Vpu recently led to the discovery of the interferon-induced transmembrane protein BST-2 (CD317; tetherin) as a novel component of the innate defense against enveloped viruses. BST-2 is an unusually structured protein that restricts the release of fully formed progeny virions from infected cells, presumably by a direct retention mechanism that is independent of any viral protein target. Its spectrum of activity includes at least four virus families: retroviruses, filoviruses, arenaviruses, and herpesviruses. Viral antagonists of BST-2 include HIV-1 Vpu, HIV-2 and SIV Env, SIV Nef, the Ebola envelope glycoprotein, and the K5 protein of KSHV. The mechanisms of antagonism are diverse and currently include viral cooption of cellular endosomal trafficking and protein degradation pathways, including those mediated by ubiquitination. Orthologs of human BST-2 are present in mammals. Primate BST-2 proteins are differentially sensitive to antagonism by lentiviral Vpu and Nef proteins, suggesting that BST-2 has subjected lentiviruses to evolutionary pressure and presents barriers to cross-species transmission. BST-2 functions not only as an effector of the interferon-induced antiviral response but also as a negative feedback regulator of interferon production by plasmacytoid dendritic cells. Future work will focus on the role and regulation of BST-2 during the innate response to viral infection, on the mechanisms of restriction and of antagonism by viral gene products, and on the role of BST-2 in primate lentiviral evolution. The augmentation of BST-2 activity and the inhibition of virally encoded antagonists, in particular Vpu, represent new approaches to the prevention and treatment of HIV-1 infection.
Through the use of chimeric CXCR4/CCR5 receptors we have previously shown that CCR5-tropic (R5) HIV-1 isolates acquire a more flexible receptor use over time, and that this links to a reduced viral susceptibility to inhibition by the CCR5 ligand RANTES. These findings may have relevance with regards to the efficacy of antiretroviral compounds that target CCR5/virus interactions. Compartmentalized discrepancies in coreceptor use may occur, which could also affect the efficacy of these compounds at specific anatomical sites, such as within the CNS. In this cross-sectional study we have used wild-type CCR5 and CXCR4 as well as chimeric CXCR4/CCR5 receptors to characterize coreceptor use by paired plasma and cerebrospinal fluid (CSF) isolates from 28 HIV-1-infected individuals. Furthermore, selected R5 isolates, with varying chimeric receptor use, were tested for sensitivity to inhibition by the CCR5 antagonist TAK-779. Discordant CSF/plasma virus coreceptor use was found in 10/28 patients. Low CD4+ T cell counts correlated strongly with a more flexible mode of R5 virus CCR5 usage, as disclosed by an increased ability to utilize chimeric CXCR4/CCR5 receptors, specifically receptor FC-2. Importantly, an elevated ability to utilize chimeric receptors correlated with a reduced susceptibility to inhibition by TAK-779. Our findings show that a discordant CSF and plasma virus coreceptor use is not uncommon. Furthermore, we provide support for an emerging paradigm, where the acquisition of a more flexible mode of CCR5 usage is a key event in R5 virus pathogenesis. This may, in turn, negatively impact the efficacy of CCR5 antagonist treatment in late stage HIV-1 disease.
The goal of this study was to develop an in vivo murine model that can be used to study the influence of HSV-2 on HIV infection. Mice expressing transgenes for human CD4, CCR5 and Cyclin T1 were infected intra-vaginally with HSV-2 and 3-7 days later infected with HIV. HIV DNA was detected by real time PCR. The frequency of detection of HIV DNA was significantly higher (65%) in vaginal tissue of HSV-2-infected mice compared to mock-infected mice (35%) when HIV was given 3 days after HSV-2. HSV-2 infected mice also had significantly higher levels of HIV DNA in vaginal tissue. HIV DNA was not detected in vaginal tissue of mice lacking human CD4. Longer periods (5 or 7 days) between infection with HSV-2 and HIV did not increase the frequency of detection or the amount of HIV DNA detected. HIV DNA was also detected in lymph nodes from some of the mice that were infected intra-vaginally with HSV-2 and HIV. Flow cytometric and mRNA analysis of human CD4 in vaginal tissue suggested that HSV-2 infection increased the number of T cells expressing human CD4 in vaginal tissue. This study provides evidence that HIV infection of cells occurs in the vagina of mice expressing human CD4, CCR5 and Cyclin T1 and that HSV-2 infection increases HIV infection. These findings demonstrate that this model can be used to study the mechanisms responsible for increased susceptibility to HIV in HSV-2-infected persons and for testing preventative treatments.
HIV-1 trans-infection is a process by which one cell acts as an HIV-1 “escort” to enhance infection of another. There has recently been much debate concerning (i) the types of cells that may act as escorts, (ii) requirements for virus internalization by the escort, and (iii) the sensitivity of trans-infection to inhibition by neutralizing antibodies. To address these questions, trans-infection was monitored by incubating target cells with HIV-1 in the presence or absence of mouse or human cells as candidate escorts in vitro. After a two day culture, target cells were tested for levels of HIV-1 infection. Results showed that a variety of murine and human cells were capable escorts for HIV-1 trans-infection. Cell integrity was not required, as escorts could be freeze/thawed (or fractionated to yield purified membranes/microsomes) prior to their incubation with HIV-1. In fact, the freeze/thawed or fractionated cells were often superior to their viable counterparts as mediators of trans-infection. The process was sensitive to antibody neutralization. Confirmatory experiments were conducted with more than one target cell and more than one source of HIV-1. Results demonstrated that there may be multiple cell types and mechanisms with which trans-infection can be accomplished. Apparently the simple binding of fragmented escort membranes to HIV-1 may be sufficient to enhance virus fusion or endocytosis at the target cell surface. The fact that dead cells or membranes can support this activity may explain, at least in part, the high frequency of human HIV-1 infections at sites of tissue damage.
HIV-1 Trans-infection; membranes; microsomes; neutralizing antibodies
HIV-1 transinfection is a process by which one cell acts as an HIV-1 “escort” to enhance infection of another. There has recently been much debate concerning (1) the types of cells that may act as escorts, (2) requirements for virus internalization by the escort, and (3) the sensitivity of transinfection to inhibition by neutralizing antibodies. To address these questions, transinfection was monitored by incubating target cells with HIV-1 in the presence or absence of mouse or human cells as candidate escorts in vitro. After a 2-day culture, target cells were tested for levels of HIV-1 infection. Results showed that a variety of murine and human cells were capable escorts for HIV-1 transinfection. Cell integrity was not required, as escorts could be freeze/thawed (or fractionated to yield purified membranes/microsomes) prior to their incubation with HIV-1. In fact, the freeze/thawed or fractionated cells were often superior to their viable counterparts as mediators of transinfection. The process was sensitive to antibody neutralization. Confirmatory experiments were conducted with more than one target cell and more than one source of HIV-1. Results demonstrated that there may be multiple cell types and mechanisms with which transinfection can be accomplished. Apparently the simple binding of fragmented escort membranes to HIV-1 may be sufficient to enhance virus fusion or endocytosis at the target cell surface. The fact that dead cells or membranes can support this activity may explain, at least in part, the high frequency of human HIV-1 infections at sites of tissue damage.
The goal of this study was to develop an in vivo murine model that can be used to study the influence of HSV-2 on HIV infection. Mice expressing transgenes for human CD4, CCR5, and Cyclin T1 were infected intravaginally with HSV-2 and 3–7 days later infected with HIV. HIV DNA was detected by real-time PCR. The frequency of detection of HIV DNA was significantly higher (65%) in vaginal tissue of HSV-2-infected mice compared to mock-infected mice (35%) when HIV was given 3 days after HSV-2. HSV-2-infected mice also had significantly higher levels of HIV DNA in vaginal tissue. HIV DNA was not detected in vaginal tissue of mice lacking human CD4. Longer periods (5 or 7 days) between infection with HSV-2 and HIV did not increase the frequency of detection or the amount of HIV DNA detected. HIV DNA was also detected in lymph nodes from some of the mice that were infected intravaginally with HSV-2 and HIV. Flow cytometric and mRNA analysis of human CD4 in vaginal tissue suggested that HSV-2 infection increased the number of T cells expressing human CD4 in vaginal tissue. This study provides evidence that HIV infection of cells occurs in the vagina of mice expressing human CD4, CCR5, and Cyclin T1 and that HSV-2 infection increases HIV infection. These findings demonstrate that this model can be used to study the mechanisms responsible for increased susceptibility to HIV in HSV-2-infected persons and for testing preventative treatments.
To delineate the mechanistic basis for the epidemiological association between methamphetamine use and accelerated progression to AIDS, we evaluated the direct in vitro and in vivo effects of methamphetamine on HIV-1 replication. Methamphetamine administration significantly increased HIV-1 production by both HIV-infected monocytes and CD4 T lymphocytes in vitro. In addition, in vivo methamphetamine treatment increased HIV production and viremia in mice transgenic for a replication-competent HIV provirus and human cyclinT1. Methamphetamine activated transcription of the HIV long terminal repeat (LTR) regulatory region, was associated with nuclear translocation of NF-κB. Our results provide further insights into the mechanisms by which methamphetamine accelerates disease course in HIV-infected individuals.
Many human immunodeficiency virus (HIV) proteins including Tat are produced by HIV-infected astrocytes and secreted into the brain resulting in extensive neuronal damage that contributes to the pathogenesis of HIV dementia. The neuroprotective hormone 17β-estradiol (E2) is known to negatively regulate the HIV transcriptional promoter in human fetal astrocytes (SVGA cell line) in a Tat-dependent manner. In the present study we extended our investigation in HIV-infected SVGA cells and found a reduction in HIV p24 levels following E2 treatment in comparison to control. Although many E2-mediated events occur through estrogen receptor alpha (ERα), we found low levels of ERα mRNA and failed to detect ERα protein in SVGA cells. Paradoxically, when ERα was overexpressed the E2-mediated decrease in Tat transactivation of the promotor was prevented. To determine whether ERα expression is altered in the human brain following HIV infection, postmortum hippocampal tissue was obtained from cognitively normal HIV− and HIV+ patients, patients diagnosed with either mild cognitive/motor disorder (MCMD) or HIV-associated dementia (HAD). Immunohistochemistry and quantitative real-time PCR (qRT-PCR) for ERα and glial fibrillary acidic protein (GFAP) showed that ERα mRNA levels were not significantly different between groups, while GFAP increased in the hippocampus in the HIV+ compared to the HIV− group and was decreased in the MCMD and HAD subgroups compared to HIV+ controls. Notably the ratio of ERα-positive reactive astrocytes to total reactive astrocytes increased and significantly correlated with the severity of cognitive impairment following HIV infection. The data suggest that E2 would have the most dramatic effect in reducing HIV transcription early in the disease process when the subpopulation of astrocytes expressing ERα is low.
A single dose of tenofovir/emtricitabine (TDF/FTC) during labor significantly reduces peripartum nevirapine-associated viral drug resistance when measured by consensus HIV sequencing. It is unknown whether this effect extends to HIV subpopulations of <25–50%. We conducted a randomized trial of single-dose TDF/FTC added to peripartum nevirapine to reduce drug resistance associated with nonnucleoside reverse transcriptase inhibitors (NNRTIs). To detect mutations for NNRTIs comprising ≥2% of the viral population, we used an oligonucleotide ligation assay (OLA) at codons 103, 106, 181, and 190 of HIV reverse transcriptase. To assess development of drug resistance mutations to our study intervention, OLA was also performed at codons 65 and 184. Among the 328 women included in the 2-week analysis, those receiving TDF/FTC were less likely to have NNRTI resistance by OLA (RR = 0.40, 95% CI = 0.21–0.77). A similar trend was observed among the 315 women included in the 6-week analysis (RR = 0.45, 95% CI = 0.31–0.66). Only two (1%) specimens had detectable K65R by OLA. Both were at 6 weeks postpartum; one was detected in the intervention arm and one in the control arm (p = 0.96). M184V was not detected. The ability of single-dose TDF/FTC to protect against peripartum NVP-induced NNRTI resistance extends to minority populations. This efficacy is achieved without significant selection of TDF- or FTC-resistant viruses.
This study analyzes immunologic markers to predict and diagnose tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) in HIV and TB coinfected adults who initiated antiretroviral therapy (ART) in Thailand. T helper 1 cytokines interleukin (IL)-2, IL-12, and interferon-gamma (IFN-γ) levels in response to PPD and RD1 antigens were assessed prior to ART, at weeks 6, 12, and 24 of treatment, and at time of TB-IRIS. Of 126 subjects, 22 (17.5%) developed TB-IRIS; 14 (64%) subjects received steroid treatment and 3 (14%) received NSAIDs; none of the subjects died. Median interval between ART initiation and TB-IRIS development was 14 days. IFN-γ, IL-2, and IL-12 responses did not differ between TB-IRIS and no TB-IRIS subjects (p > 0.05). More research into the immunopathogenesis of TB-IRIS and diagnostic potential of cytokine markers is warranted.
To analyze HIV-1 subtype distribution, sequence analysis was performed on serum specimens obtained in 1994 from the Rakai Health Sciences community cohort in Uganda. Portions of gag-p24 and env-gp41 were sequenced and HIV subtype was determined for 773 subjects residing in 10 community clusters in rural Uganda. Subtypes A (17%) and D (70%) were the most common strains in the population. Subtype distribution varied by geographic region with significantly more subtype A in northern community clusters compared with southern clusters (21% vs. 8%, p < 0.001) and more subtype D in southern clusters compared with northern clusters (78% vs. 65%, p < 0.008). These data illustrate the geographic complexity of subtype variation, which has important implications for HIV-1 vaccine design.
HIV infection is associated with left ventricular (LV) dysfunction and accelerated atherosclerosis. These conditions result in elevation of plasma natriuretic peptide (NP) levels. The present study compares N-terminal-pro-BNP (NT-pro-BNP) levels in HIV-infected and -uninfected women and identifies factors influencingNT-pro-BNP levels in HIV-infected women. A total of 454 HIV-infected and 200 HIV-uninfected participants from the Women's Interagency HIV Study (WIHS) had NT-pro-BNP determination. Elevated NT-pro-BNP level was defined using previously determined age stratified cut-off values of >164 ng/liter (age <60 years) and >225 (age ≥ 60 years). HIV-infected women were older (41.6 ± 8.9 vs. 38.9 ± 10.5 years, p < 0.01) and were more likely to have anemia, hepatitis C virus (HCV) antibodies, and kidney dysfunction than HIV-uninfected women. HIV-infected women had significantly higher NT-pro-BNP levels (142.4 ± 524.8 vs. 73.6 ± 115.1 ng/liter, p = 0.01) and a higher prevalence of elevated NT-pro-BNP (12.1% vs. 7.5%; p = 0.08). In univariate analyses, elevated NT-pro-BNP was significantly associated with age, systolic BP, hypertension, anemia, triglyceride levels, kidney disease, and HCV seropositivity, but not HIV infection. In multivariate analysis, elevated NT-pro-BNP levels were significantly associated with anemia and kidney function, and had a borderline association with the presence of HCV antibodies. Among HIV-infected women, NT-pro-BNP levels were not independently associated with measures of severity of infection or with HAART use. Although HIV-infected women have higher NT-pro-BNP levels than HIV-uninfected women, the differences are due to non-HIV factors such as anemia, kidney disease, and HCV coinfection. These findings suggest that natriuretic peptide levels are a global marker of comorbidity in the setting of HIV infection.
HIV viremia is associated with a wide range of immune dysfunctions that contribute to the immunocompromised state. HIV viremia has been shown to have a broad effect on several immune cell types and/or their interactions that are vital for mounting an effective immune response. In this study, we investigated the integrity of plasmacytoid dendritic cell (pDC)-NK cell interactions among HIV viremic, aviremic, and seronegative individuals. We describe a critical defect in the ability of pDCs from HIV-infected individuals to secrete IFN-α and TNF and subsequently activate NK cells. We also describe an inherent defect on NK cells from HIV-infected individuals to respond to pDC-secreted cytokines. Furthermore, we were able to demonstrate a direct effect of HIV trimeric gp120 on NK cells in vitro similar to that described ex vivo. Finally, we were able to establish that the HIV gp120-mediated suppressive effect on NK cells was a result of its binding to the integrin α4β7 expressed on NK cells. These findings suggest a novel mechanism by which HIV is capable of suppressing an innate immune function in infected individuals.
The oral mucosa is relatively resistant to human immunodeficiency virus type 1 (HIV-1) transmission. The mechanisms contributing to this resistance remain incompletely understood, but may include HIV-induced synthesis of innate immune factors. We used fully differentiated oral epithelium as a surrogate for the oral mucosa in vivo, exposed it to X4- and R5-tropic HIV-1 in culture, and quantified mRNA expression of six innate immune factors. Neither virus increased expression of human beta defensin 2 (hBD-2) mRNA over supernatants from uninfected lymphoblast controls. HIV-1 also failed to induce mRNA of four additional innate immunity-related genes. Similar results were obtained with oral monolayer epithelial cells. Interestingly, the X4-tropic virus inhibited mRNA expression of hBD-2, and of three of the other factors, at higher dosages in the differentiated oral epithelium but not the monolayers. The failure of HIV-1 to induce innate immune factors in the differentiated epithelium was not due to a lack of tissue penetration, as we detected fluorescence-tagged virions up to 30 μm deep from the apical surface. HIV-1 does not trigger de novo innate immune factor synthesis in oral epithelium, pointing to the role of a constitutive innate immunity for protection against HIV-1 in the oral cavity.
Sequence characterization of the near full-length genomes of HIV-1 isolates BCF-Dioum and BCF-Kita, originating from the Democratic Republic of Congo (DRC), was continued. These NED panel isolates, contributed by F. Brun-Vezinet (ENVA-France), were first identified as subtypes G and H, respectively. Our earlier analyses of portions of their pol genes showed that both were likely to be intersubtype recombinants of different composition. This study analyzed the remainder of each genome, confirming them to be complex recombinants. The BCF-Dioum genome resembles CRF06_cpx strains found in West Africa, composed of subtypes A/G/J/K. The BCF-Kita genome is a unique complex recombinant A–F–G–H–K–U strain. These data support previous observations of the complexity of strains originating from the DRC. BCF-Dioum may be a suitable strain for standards and reagents since it matches a defined circulating recombinant form. Studies and reagents made from BCF-Kita should take into account its complex genome.
The ability of HIV to establish a latent infection causes life-long virus persistence, even after long-term highly active antiretroviral therapy (HAART). The role that latency is playing in preventing clearance of the virus infection has become evident in recent years. Patients who have been successfully treated with ART, having undetectable levels of viral RNA (below 50 copies/ml) in the plasma for years, experienced rapid virus rebound on withdrawal of therapy. Activation of latent proviruses from the infected cells in combination with ART is a therapeutic strategy that may lead to the complete elimination of HIV infection. We report here that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor that has been approved for the treatment of cutaneous T cell lymphoma (CTCL), can activate an HIV-1 vector provirus in a cell model system. Treatment of cells harboring a latent, HIV-1-derived provirus caused activation of both early and late viral gene expression, acetylation of nucleosome on the 5’ long terminal repeat (LTR), and remodeling of the chromatin at the 5’ LTR. Several compounds, including valproic acid, have been tested for their ability to activate latent HIV-1, but have met with disappointing results. SAHA, a relatively nontoxic, FDA-approved compound, should be considered for developing a strategy to eliminate HIV from patients.
This study aimed to determine HIV, HCV, and syphilis prevalence and correlates, and to characterize the molecular epidemiology of HIV-1 among injecting drug users (IDUs) in Dushanbe, Tajikistan. A cross-sectional study assessing risk factors for HIV and HCV through an interview administered survey was conducted. A total of 491 active adult IDUs were recruited from May to November 2004 in Dushanbe, Tajikistan. HIV-1 antibody status was determined with rapid testing and confirmed with ELISA. HCV antibody testing was conducted using a BIOELISA HCV kit. HIV-1 subtyping was done on a subset with full-length sequencing. Correlates of HIV and HCV infection were assessed using logistic regression. Overall prevalence of HIV was 12.1%, HCV was 61.3%, and syphilis was 15.7%. In a multivariate logistic regression model controlling for gender and ethnicity, daily injection of narcotics [odds ratio (OR) OR 3.22] and Tajik nationality (OR 7.06) were significantly associated with HIV status. Tajik nationality (OR 1.91), history of arrest (OR 2.37), living/working outside Tajikistan in the past 10 years (OR 2.43), and daily injection of narcotics (OR 3.26) were significantly associated with HCV infection whereas being female (OR 0.53) and always using a sterile needle (OR 0.47) were inversely associated with HCV infection. Among 20 HIV-1-positive IDU with specimens available for typing, 10 were subtype A, 9 were CRF02_AG, and one was an A-CRF02_AG recombinant. Epidemics of HIV-1, HCV, and drug use are underway in Dushanbe. The molecular epidemiology is distinctive, with West African variants accounting for roughly 50% of prevalent infections. Targeted prevention programs offering both needle exchange programs and opiate substitution therapies are urgently called for to prevent the further spread of HIV and HCV in Tajikistan.
To assess differences in arterial wave reflection, a marker of atherosclerosis, in HIV-positive and HIV-negative Rwandan women, applanation tonometry was performed on 276 HIV+ and 67 HIV− participants. Radial artery pressure waveforms were recorded and central aortic waveforms were derived by validated transfer function. Central augmentation index (C-AI), central pulse pressure (C-PP), and peripheral augmentation index (P-AI) were measured. HIV+ participants were younger and had lower diastolic blood pressure (BP) and 41% of the HIV+ women were taking antiretroviral therapy (ART). Mean C-AI and P-AI were significantly lower in HIV-infected than in uninfected participants (20.3 ± 12.0 vs. 25.5 ± 12.1, p = 0.002 and 74.6 ± 18.8 vs. 83.7 ± 20.0, p < 0.001). After age matching, C-AI, C-PP, and P-AI were similar among the groups. On multivariate analysis, age, heart rate, weight, and mean arterial pressure were independently associated with C-AI (R2 = 0.33, p < 0.0001). Among HIV-infected women, current CD4 count did not correlate with C-AI (Rho = −0.01, p = 0.84), C-PP (Rho = 0.09, p = 0.16), or P-AI (Rho = −0.01, p = 0.83). In conclusion, HIV infection was not associated with increased arterial wave reflection in women with little exposure to antiretroviral therapy and without CV risk factors. Whether long-term ART increases measures of arterial stiffness remains unknown.
In previous studies on mechanisms of HIV-1 mediated pathogenesis we showed that bystander apoptosis mediated by cell surface expressed HIV-1 Env correlated with the fusogenic properties of the gp41 subunit of Env. A crucial step in HIV gp41-mediated fusion is the re-folding of the protein into a six helix bundle along the N- and C-terminal coiled coil domains. These domains have been targeted by peptide inhibitors that inhibit gp41 mediated fusion. One of these inhibitors, Enfuvirtide, is the first such drug approved for therapy. More recently, clinical data suggests that the beneficial effects of Enfuvirtide extend beyond virus suppression and are associated with certain resistance mutations in gp41. In this study we characterized the bystander apoptosis inducing potential of mutants associated with increased CD4 counts that arise during Enfuvirtide therapy. While all mutant clones were reduced in both cell to cell fusion activity and apoptosis induction there was limited effect on virus infection or replication. The viruses found to have apoptosis inducing activity in the order WT>V38M>V38A>G36D>V38E which correlated with cell to cell fusion but not infection. Interestingly, the level of resistance as determined by IC50 of Enfuvirtide also correlated inversely with both cell fusion and apoptosis in that the most resistant Envs were least fusogenic and pathogenic. This suggests the beneficial effects of Enfuvirtide therapy beyond virus suppression maybe mediated by selecting less pathogenic HIV isolates over time.
In previous studies on mechanisms of HIV-1-mediated pathogenesis we showed that bystander apoptosis mediated by cell surface-expressed HIV-1 Env correlated with the fusogenic properties of the gp41 subunit of Env. A crucial step in HIV gp41-mediated fusion is the refolding of the protein into a six-helix bundle along the N- and C-terminal coiled-coil domains. These domains have been targeted by peptide inhibitors that inhibit gp41-mediated fusion. One of these inhibitors, enfuvirtide, is the first such drug approved for therapy. More recently, clinical data suggest that the beneficial effects of enfuvirtide extend beyond virus suppression and are associated with certain resistance mutations in gp41. In this study we characterized the bystander apoptosis-inducing potential of mutants associated with increased CD4 counts that arise during enfuvirtide therapy. Whereas all mutant clones were reduced in both cell-to-cell fusion activity and apoptosis induction there was limited effect on virus infection or replication. The viruses were found to have apoptosis-inducing activity in the order WT > V38M > V38A > G36D > V38E, which correlated with cell-to-cell fusion but not infection. Interestingly, the level of resistance as determined by the IC50 of enfuvirtide also correlated inversely with both cell fusion and apoptosis in that the most resistant Envs were the least fusogenic and pathogenic. This suggests the beneficial effects of enfuvirtide therapy beyond virus suppression may be mediated by selecting less pathogenic HIV isolates over time.