http://www.aidsrestherapy.com The latest research articles published by AIDS Research and Therapy 2010-07-28T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ Background: HIV protease (PR) is a virus-encoded aspartic protease that is essential for viral replication and infectivity. The fully active and mature dimeric protease is released from the Gag-Pol polyprotein as a result of precursor autoprocessing. Results: We here describe a simple model system to directly examine HIV protease autoprocessing in transfected mammalian cells. A fusion precursor was engineered encoding GST fused to a well-characterized miniprecursor, consisting of the mature protease along with its upstream transframe region (TFR), and small peptide epitopes to facilitate detection of the precursor substrate and autoprocessing products. In HEK 293T cells, the resulting chimeric precursor undergoes effective autoprocessing, producing mature protease that is rapidly degraded likely via autoproteolysis. The known protease inhibitors Darunavir and Indinavir suppressed both precursor autoprocessing and autoproteolysis in a dose-dependent manner. Protease mutations that inhibit Gag processing as characterized using proviruses also reduced autoprocessing efficiency when they were introduced to the fusion precursor. Interestingly, autoprocessing of the fusion precursor requires neither the full proteolytic activity nor the majority of the N-terminal TFR region. Conclusions: We suggest that the fusion precursors provide a useful system to study protease autoprocessing in mammalian cells, and may be further developed for screening of new drugs targeting HIV protease autoprocessing. http://www.aidsrestherapy.com/content/7/1/27 Liangqun Huang Chaoping Chen AIDS Research and Therapy 2010, 7:27 2010-07-28T00:00:00Z doi:10.1186/1742-6405-7-27 AIDS Research and Therapy 1742-6405 7 27 2010-07-28T00:00:00Z PDF Background: Nef is a 27 KDa HIV-1 accessory protein. It downregulates CD4 from infected cell surface, a mechanism critical for efficient viral replication and pathogenicity. Agents that antagonize the Nef-mediated CD4 downregulation may offer a new class of drug to combat HIV infection and disease. TPCK (N--p-tosyl-L-phenylalanine chloromethyl ketone) and TLCK (N--p-tosyl-L-lysine chloromethyl ketone) are alkylation reagents that chemically modify the side chain of His or Cys residues in a protein. In search of chemicals that inhibit Nef function, we discovered that TPCK and TLCK alkylated HIV Nef. Methods: Nef modification by TPCK was demonstrated on reducing SDS-PAGE. The specific cysteine residues modified were determined by site-directed mutagenesis and mass spectrometry (MS). The effect of TPCK modification on Nef-CD4 interaction was studied using fluorescence titration of a synthetic CD4 tail peptide with recombinant Nef-His protein. The conformational change of Nef-His protein upon TPCK-modification was monitored using CD spectrometry Results: Incubation of Nef-transfected T cells, or recombinant Nef-His protein, with TPCK resulted in mobility shift of Nef on SDS-PAGE. Mutagenesis analysis indicated that the modification occurred at Cys55 and Cys206 in Nef. Mass spectrometry demonstrated that the modification was a covalent attachment (alkylation) of TPCK at Cys55 and Cys206. Cys55 is next to the CD4 binding motif (A56W57L58) in Nef required for Nef-mediated CD4 downregulation and for AIDS development. This implies that the addition of a bulky TPCK molecule to Nef at Cys55 would impair Nef function and reduce HIV pathogenicity. As expected, Cys55 modification reduced the strength of the interaction between Nef-His and CD4 tail peptide by 50%. Conclusions: Our data suggest that this Cys55-specific alkylation mechanism may be exploited to develop a new class of anti HIV drugs. http://www.aidsrestherapy.com/content/7/1/26 Yong-Jiu Jin Xiaoping Zhang Catherine Yi Cai Steven Burakoff AIDS Research and Therapy 2010, 7:26 2010-07-26T00:00:00Z doi:10.1186/1742-6405-7-26 AIDS Research and Therapy 1742-6405 7 26 2010-07-26T00:00:00Z PDF ObjectiveRecent studies have shown that the current guidelines suggesting immunologic monitoring to determine response to highly active antiretroviral therapy (HAART) are inadequate. We assessed whether routinely collected clinical markers could improve prediction of concurrent HIV RNA levels. Methods: We included individuals followed within the Johns Hopkins HIV Clinical Cohort who initiated antiretroviral therapy and had concurrent HIV RNA and biomarker measurements [greater than or equal to]4 months after HAART. A two tiered approach to determine whether clinical markers could improve prediction included: 1) identification of predictors of HIV RNA levels >500 copies/ml and 2) construction and validation of a prediction model. Results: Three markers (mean corpuscular hemoglobin [MCH], CD4, and change in percent CD4 from pre-HAART levels) in addition to the change in MCH from pre-HAART levels contained the most predictive information for identifying an HIV RNA >500 copies/ml. However, MCH and change in MCH were the two most predictive followed by CD4 and change in percent CD4. The logistic prediction model in the validation data had an area under the receiver operating characteristic curve of 0.85, and a sensitivity and specificity of 0.74 (95% CI: 0.69-0.79) and 0.89 (95% CI: 0.86-0.91), respectively. Conclusions: Immunologic criteria have been shown to be a poor guideline for identifying individuals with high HIV RNA levels. MCH and change in MCH were the strongest predictors of HIV RNA levels >500. When combined with CD4 and percent CD4 as covariates in a model, a high level of discrimination between those with and without HIV RNA levels >500 was obtained. These data suggest an unexplored relationship between HIV RNA and MCH. http://www.aidsrestherapy.com/content/7/1/25 Bryan Lau Geetanjali Chander Stephen Gange Richard Moore AIDS Research and Therapy 2010, 7:25 2010-07-23T00:00:00Z doi:10.1186/1742-6405-7-25 AIDS Research and Therapy 1742-6405 7 25 2010-07-23T00:00:00Z PDF Background: Understanding co-receptor tropism of HIV-1 strains circulating in India will provide key analytical leverage for assessing the potential usefulness of newer antiretroviral drugs such as chemokine co-receptor antagonists among Indian HIV-infected populations. The objective of this study was to determine using in silico methods, HIV-1 tropism among a large number of Indian isolates both from primary clinical isolates as well as from database-derived sequences. Results: R5-tropism was seen in 96.8% of a total of 1045 HIV-1 subtype C Indian sequences. Co-receptor prediction of 15 primary clinical isolates detected two X4-tropic strains using the C-PSSM matrix. R5-tropic HIV-1 subtype C V3 sequences were conserved to a greater extent than X4-tropic strains. X4-tropic strains were obtained from subjects who had a significantly longer time since HIV diagnosis (96.5 months) compared to R5-tropic strains (20.5 months). Conclusions: High prevalence of R5 tropism and greater homogeneity of the V3 sequence among HIV-1 subtype C strains in India suggests the potential benefit of CCR5 antagonists as a therapeutic option in India. http://www.aidsrestherapy.com/content/7/1/24 Ujjwal Neogi Sreenivasa Prarthana George DSouza Ayesha De Costa Vijesh Kuttiatt Udaykumar Ranga Anita Shet AIDS Research and Therapy 2010, 7:24 2010-07-21T00:00:00Z doi:10.1186/1742-6405-7-24 AIDS Research and Therapy 1742-6405 7 24 2010-07-21T00:00:00Z PDF Background: Stavudine continues to be widely used in resource poor settings despite its toxicity. Our objective was to determine an association between plasma stavudine concentrations and lipoatrophy, concentrations of glucose, lactate and triglycerides.MethodParticipants were enrolled in a cross-sectional study with lipoatrophy assessment, oral glucose tolerance test, fasting triglycerides, finger prick lactate, and stavudine concentrations. Individual predictions of the area under the concentration curve (AUC) were obtained using a population pharmacokinetic approach. Logistic regression models were fitted to assess the association between stavudine geometric mean ratio >1 and impaired fasting glucose, impaired glucose tolerance, hyperlactataemia, hypertriglyceridaemia, and lipoatrophy. Results: There were 47 study participants with a median age of 34 years and 83% were women. The median body mass index and waist:hip ratio was 24.5 kg/m2 and 0.85 respectively. The median duration on stavudine treatment was 14.5 months. The prevalence of lipoatrophy, impaired fasting glucose, impaired glucose tolerance, hyperlactataemia, and hypertriglyceridaemia were 34%, 19%, 4%, 32%, and 23% respectively. Estimated median (interquartile range) stavudine AUC was 2191 (1957 to 2712) ng * h/mL. Twenty two participants had stavudine geometric mean ratio >1. Univariate logistic regression analysis showed no association between stavudine geometric mean ratio > 1 and impaired fasting glucose (odds ratio (OR) 2.00, 95% CI 0.44 to 9.19), impaired glucose tolerance (OR 1.14, 95%CI 0.07 to 19.42), hyperlactataemia (OR 2.19, 95%CI 0.63 to 7.66), hypertriglyceridaemia (OR 1.75, 95%CI 0.44 to 7.04), and lipoatrophy (OR 0.83, 95%CI 0.25 to 2.79). Conclusions: There was a high prevalence of metabolic complications of stavudine, but these were not associated with plasma stavudine concentrations. Until there is universal access to safer antiretroviral drugs, there is a need for further studies examining the pathogenesis of stavudine-associated toxicities. http://www.aidsrestherapy.com/content/7/1/23 Phumla Sinxadi Jan-Stefan van der Walt Helen McIlleron Motasim Badri Peter Smith Joel Dave Naomi Levitt Gary Maartens AIDS Research and Therapy 2010, 7:23 2010-07-14T00:00:00Z doi:10.1186/1742-6405-7-23 AIDS Research and Therapy 1742-6405 7 23 2010-07-14T00:00:00Z PDF Background: At present, there is no effective vaccine or other approved product for the prevention of sexually transmitted human immunodeficiency virus type 1 (HIV-1) infection. It has been reported that women in resource-poor communities use vaginally applied citrus juices as topical microbicides. These easily accessible food products have historically been applied to prevent pregnancy and sexually transmitted diseases. The aim of this study was to evaluate the efficacy and cytotoxicity of these substances using an established topical microbicide testing algorithm. Freshly squeezed lemon and lime juice and household vinegar were tested in their original state or in pH neutralized form for efficacy and cytotoxicity in the CCR5-tropic cell-free entry and cell-associated transmission assays, CXCR4-tropic entry and fusion assays, and in a human PBMC-based anti-HIV-1 assay. These products were also tested for their effect on viability of cervico-vaginal cell lines, human cervical explant tissues, and beneficial Lactobacillus species. Results: Natural lime and lemon juice and household vinegar demonstrated anti-HIV-1 activity and cytotoxicity in transformed cell lines. Neutralization of the products reduced both anti-HIV-1 activity and cytotoxicity, resulting in a low therapeutic window for both acidic and neutralized formulations. For the natural juices and vinegar, the IC50 was [less than or equal to]3.5 (0.8-3.5) % and the TC50 [less than or equal to]6.3 (1.0-6.3) %. All three liquid products inhibited viability of beneficial Lactobacillus species associated with vaginal health. Comparison of three different toxicity endpoints in the cervical HeLa cell line revealed that all three products affected membrane integrity, cytosolic enzyme release, and dehydrogenase enzyme activity in living cells. The juices and vinegar also exerted strong cytotoxicity in cervico-vaginal cell lines, mainly due to their acidic pH. In human cervical explant tissues, treatment with 5% lemon or lime juice or 6% vinegar induced toxicity similar to application of 100ug/ml nonoxynol-9, and exposure to 10% lime juice caused tissue damage comparable to treatment with 5% Triton-X-100. Conclusions: Lemon and lime juice and household vinegar do not fulfill the safety criteria mandated for a topical microbicide. As a result of their unphysiological formulation for the vaginal tract, they exhibit cytotoxicity to human cell lines, human vaginal tissues, and beneficial vaginal Lactobacillus species. http://www.aidsrestherapy.com/content/7/1/22 Carol Lackman-Smith Beth Snyder Katherine Marotte Mark Osterling Marie Mankowski Maureen Jones Lourdes Nieves-Duran Nicola Richardson-Harman James Cummins Brigitte Sanders-Beer AIDS Research and Therapy 2010, 7:22 2010-07-09T00:00:00Z doi:10.1186/1742-6405-7-22 AIDS Research and Therapy 1742-6405 7 22 2010-07-09T00:00:00Z PDF Background: The search for disease biomarkers within human peripheral fluids has become a favorable approach to preventative therapeutics throughout the past few years. The comparison of normal versus disease states can identify an overexpression or a suppression of critical proteins where illness has directly altered a patient's cellular homeostasis. In particular, the analysis of HIV-1 infected serum is an attractive medium with which to identify altered protein expression due to the ease and non-invasive methods of collecting samples as well as the corresponding insight into the in vivo interaction of the virus with infected cells/tissue. The utilization of proteomic techniques to globally identify differentially expressed serum proteins in response to HIV-1 infection is a significant undertaking that is complicated due to the innate protein profile of human serum. Results: Here, the depletion of 12 of the most abundant serum proteins, followed by two-dimensional gel electrophoresis coupled with identification of these proteins using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, has allowed for the identification of differentially expressed, low abundant serum proteins. We have analyzed and compared serum samples from HIV-1 infected subjects who are being treated using highly active antiretroviral therapy (HAART) to those who are latently infected but have not progressed to AIDS despite the absence of treatment, i.e. long term non-progressors (LTNPs). Here we have identified unique serum proteins that are differentially expressed in LTNP HIV-1 patients and may contribute to the ability of these patients to combat HIV-1 infection in the absence of HAART. We focused on the cdk4/6 cell cycle inhibitor p16INK4A and found that the treatment of HIV-1 latently infected cell lines with p16INK4A decreases viral production despite it not being expressed endogenously in these cells. Conclusions: Identification of these unique proteins may serve as an indication of altered viral states in response to infection as well as a natural phenotypic variability in response to HIV-1 infection in a given population. http://www.aidsrestherapy.com/content/7/1/21 Rachel Van Duyne Irene Guendel Kylene Kehn-Hall Rebecca Easley Zachary Klase Chenglong Liu Mary Young Fatah Kashanchi AIDS Research and Therapy 2010, 7:21 2010-07-06T00:00:00Z doi:10.1186/1742-6405-7-21 AIDS Research and Therapy 1742-6405 7 21 2010-07-06T00:00:00Z XML Background: Long-term survival of HIV-1 infected individuals is usually achieved by continuous administration of combination antiretroviral therapy (ART). An exception to this scenario is represented by HIV-1 infected nonprogressors (NP) which maintain relatively high circulating CD4+ T cells without clinical symptoms for several years in the absence of ART. Several lines of evidence indicate an important role of the T-cell response in the modulation of HIV-1 infection during the acute and chronic phase of the disease. Results: We analyzed the functional and the differentiation phenotype of Nef- and Tat-specific CD8+ T cells in a cohort of HIV-1 infected NP in comparison to progressors, ART-treated seropositive individuals and individuals undergoing a single cycle of ART interruption. We observed that a distinctive feature of NP is the presence of Nef-specific CD45RA+ CD8+ T cells secreting MIP-1beta but not IFN-gamma. This population was present in 7 out of 11 NP. CD45RA+ IFN-gammaneg MIP-1beta+ CD8+ T cells were not detected in HIV-1 infected individuals under ART or withdrawing from ART and experiencing a rebounding viral replication. In addition, we detected Nef-specific CD45RA+ IFN-gammaneg MIP-1beta+ CD8+ T cells in only 1 out of 10 HIV-1 infected individuals with untreated progressive disease. Conclusion: The novel antigen-specific CD45RA+ IFN-gammaneg MIP-1beta+ CD8+ T cell population represents a new candidate marker of long-term natural control of HIV-1 disease progression and a relevant functional T-cell subset in the evaluation of the immune responses induced by candidate HIV-1 vaccines. http://www.aidsrestherapy.com/content/7/1/20 Claudia Dembek Sarah Kutscher Silvia Heltai Simone Allgayer Priscilla Biswas Silvia Ghezzi Elisa Vicenzi Dieter Hoffmann Peter Reitmeir Giuseppe Tambussi Johannes Bogner Paolo Lusso Hans-J Stellbrink Elena Santagostino Thomas Vollbrecht Frank Goebel Ulrike Protzer Rika Draenert Marco Tinelli Guido Poli Volker Erfle Mauro Malnati Antonio Cosma AIDS Research and Therapy 2010, 7:20 2010-07-02T00:00:00Z doi:10.1186/1742-6405-7-20 AIDS Research and Therapy 1742-6405 7 20 2010-07-02T00:00:00Z XML Background: This study aimed to determine the therapeutic effects of highly active anti-retroviral therapy (HAART) on the clinical presentations of HIV related oral lesions (HIV-ROLs) in an adult Nigerian population. Methods: A 5 month prospective study on HAART naïve HIV positive adults recruited into the HAART program of an AIDS referral centre. HIV-ROLs were diagnosed clinically by the EEC Clearinghouse on oral problems related to HIV infection. Baseline clinical features of HIV-ROLs was documented by clinical photographs using SONY® 5.2 M Cybershot digital camera. Post HAART monthly review was conducted using clinical photographs. Results: A total of 142 patients were seen. Age range was 19 - 75 years. Mean age was 35.6 ± 10.5 (SD). Eighty (56.3%) were females. Prevalence of HIV-ROLs was 43.7%. Oral candidiasis (22.4%) was the most prevalent HIV-ROL. 114 (83.2%) patients had clinical AIDS at presentation (CDC 1993). 89.4% were placed on Tenofovir/Emtricitabine +`Nevirapine, 9.9% on Tenofovir/Emtricitabine + Efavirenz. There was strong decline in the clinical features of oral candidiasis from a month of commencing HAART. Oral hairy leukoplakia was slow in responding to HAART. Parotid gland enlargement, melanotic hyperpigmentation and Kaposi's sarcoma were more persistent and had slower response to HAART. There was no clinical change noticed in linear gingival erythema. Conclusion: HAART has different clinical effects on HIV related oral lesions depending on the size, duration of treatment and etiology of the lesions. HIV-ROLs of fungal origin have the fastest response to HAART. These lesions alongside immunologic parameters can be used as indicators of success or failure of antiretroviral therapy. http://www.aidsrestherapy.com/content/7/1/19 Olaniyi Taiwo Zuwaira Hassan AIDS Research and Therapy 2010, 7:19 2010-06-25T00:00:00Z doi:10.1186/1742-6405-7-19 AIDS Research and Therapy 1742-6405 7 19 2010-06-25T00:00:00Z XML Although access to antiretroviral therapy (ART) for the treatment of HIV has increased during the last decade, many patients are still in need of treatment. With limited funds to provide ART to millions of patients worldwide, there is a need for alternative ways to scale up ART in resource limited settings. This review provides an overview of pharmacokinetic, safety and efficacy studies of generic and reduced dose ART. The production of generic ART has greatly influenced the decline in drug prices and the increased in ART access. Generic ART has good pharmacokinetic profile, safety and efficacy. Toxicity is however the main cause for ART discontinuation. Several dose reduction studies have shown adequate pharmacokinetic parameters and short term efficacy with reduced dose ART. Ethnicity may affect drug metabolism; several pharmacokinetic studies have confirmed higher plasma ART concentration in Asians. Randomized efficacy trial of reduced versus standard ART is warranted. http://www.aidsrestherapy.com/content/7/1/18 Reshmie Ramautarsing Jintanat Ananworanich AIDS Research and Therapy 2010, 7:18 2010-06-23T00:00:00Z doi:10.1186/1742-6405-7-18 AIDS Research and Therapy 1742-6405 7 18 2010-06-23T00:00:00Z XML