Biological evaluation and molecular modelling of didanosine derivatives

Five carbonate derivatives of 50-O-20,30-dideoxyinosine (DDI, 1) have been synthesized by combination with aliphatic alcohols, with their in vitro anti-HIV activity and cytotoxicity being evaluated afterward in human peripheral blood mononuclear cells (PBMCs). One particular compound, namely DDI-Penta, exhibited an outstanding performance because it was found to have both a higher inhibitory potency and a lower cytotoxicity than the lead compound, resulting in a 100 enhancement in its selectivity index. In order to further study this phenomenon, the ability of these derivatives to bind to the cytoplasmatic nucleotidase (ncN-II) was studied by in silico methods. Also, the higher calculated lipophilicity of the synthesized compounds was proposed to improve their permeability through the cell membrane since said lipophilicity would allow a higher concentration of the corresponding prodrug inside the infected cell. Overall, a combination of an optimal lipophilicity and the ability of DDI-Penta to bind to ncN-II is suggested due to the higher potency and lower cytotoxicity observed for this compound. Based on the reported findings, we believe that the combination of certain aliphatic alcohols and DDI through a carbonate linkage could significantly increase the performance of this class of therapeutic compounds; therefore, it merits further evaluations.Fil: Ravetti, Soledad. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de Candia, Cristian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Gualdesi, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; ArgentinaFil: Pampuro, Sandra Esther. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Turk, Gabriela Julia Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Quevedo, Mario Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; ArgentinaFil: Briñon, Margarita Cristina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; Argentin

HLA-Driven Convergence of HIV-1 Viral Subtypes B and F Toward the Adaptation to Immune Responses in Human Populations

BACKGROUND: Cytotoxic T-Lymphocyte (CTL) response drives the evolution of HIV-1 at a host-level by selecting HLA-restricted escape mutations. Dissecting the dynamics of these escape mutations at a population-level would help to understand how HLA-mediated selection drives the evolution of HIV-1. METHODOLOGY/PRINCIPAL FINDINGS: We undertook a study of the dynamics of HIV-1 CTL-escape mutations by analyzing through statistical approaches and phylogenetic methods the viral gene gag sequenced in plasma samples collected between the years 1987 and 2006 from 302 drug-naive HIV-positive patients. By applying logistic regression models and after performing correction for multiple test, we identified 22 potential CTL-escape mutations (p-value<0.05; q-value<0.2); 10 of these associations were confirmed in samples biologically independent by a Bayesian Markov Chain Monte-Carlo method. Analyzing their prevalence back in time we found that escape mutations that are the consensus residue in samples collected after 2003 have actually significantly increased in time in one of either B or F subtype until becoming the most frequent residue, while dominating the other viral subtype. Their estimated prevalence in the viral subtype they did not dominate was lower than 30% for the majority of samples collected at the end of the 80's. In addition, when screening the entire viral region, we found that the 75% of positions significantly changing in time (p<0.05) were located within known CTL epitopes. CONCLUSIONS: Across HIV Gag protein, the rise of polymorphisms from independent origin during the last twenty years of epidemic in our setting was related to an association with an HLA allele. The fact that these mutations accumulated in one of either B or F subtypes have also dominated the other subtype shows how this selection might be causing a convergence of viral subtypes to variants which are more likely to evade the immune response of the population where they circulate

Antiretroviral activity and cytotoxicity of novel zidovudine (AZT) derivatives and the relation to their chemical structure

Zidovudine (AZT) was the first nucleoside analogue licensed for the treatment of HIV infection. Efforts have continuously been made to improve the therapeutic characteristics of this drug, most of them focussed on prodrugs design. Here we describe the anti-HIV-1 activity and cytotoxicity of six novel AZT derivatives namely 3′-azido-3′-deoxy-5′-O-oxalyl-N-valinethymidine, 3′-azido-3′-deoxy-5′-O-oxalyl-N-leucinethymidine, 3′-azido-3′-deoxy-5′-O-oxalyl-N-isoleucinethymidine, 3′-azido-3′-deoxy-5′-O-oxalyl-N-phenylalaninethymidine, 3′-azido-3′-deoxy-5′-O-oxalylthymidine acid, 3′-azido-3′-deoxy-5′-O-isonicotinoylthymidine and 5-chloro-6-hydroxy-5,6-dihydro-3′-azido-3′-deoxythymidine which were perfectly characterized. AZT-Val, AZT-Leu, AZT-iLeu, AZT-Phen, AZT-Ac and AZT-Iso have shown a similar or higher selectivity index than that of AZT itself, in one or both of the different cell cultures used (PBMC and MT2). However, AZT-ClOH showed no anti-HIV activity. These results suggest that using amino acids in the design of AZT derivatives improves AZT activity.Fil: Turk, Gabriela Julia Ana. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Fernández Moroni, Guillermo. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pampuro, Sandra Esther. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Brión, Margarita C.. Universidad Nacional de Córdoba; ArgentinaFil: Salomon, Horacio Eduardo. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin

Origin of Human Immunodeficiency Virus Type 1 Quasispecies Emerging after Antiretroviral Treatment Interruption in Patients with Therapeutic Failure

The emergence of antiretroviral (ARV) drug-resistant human immunodeficiency virus type 1 (HIV-1) quasispecies is a major cause of treatment failure. These variants are usually replaced by drug-sensitive ones when the selective pressure of the drugs is removed, as the former have reduced fitness in a drug-free environment. This was the rationale for the design of structured ARV treatment interruption (STI) studies for the management of HIV-1 patients with treatment failure. We have studied the origin of drug-sensitive HIV-1 quasispecies emerging after STI in patients with treatment failure due to ARV drug resistance. Plasma and peripheral blood mononuclear cell samples were obtained the day of treatment interruption (day 0) and 30 and 60 days afterwards. HIV-1 pol and env were partially amplified, cloned, and sequenced. At day 60 drug-resistant variants were replaced by completely or partially sensitive quasispecies. Phylogenetic analyses of pol revealed that drug-sensitive variants emerging after STI were not related to their immediate temporal ancestors but formed a separate cluster, demonstrating that STI leads to the recrudescence and reemergence of a sequestrated viral population rather than leading to the back mutation of drug-resistant forms. No evidence for concomitant changes in viral tropism was seen, as deduced from env sequences. This study demonstrates the important role that the reemergence of quasispecies plays in HIV-1 population dynamics and points out the difficulties that may be found when recycling ARV therapies with patients with treatment failure

Antiretroviral Activity of fucoidans extracted from the Brown Seaweed Adenocystis utricularis

Treatment of human immunodeficiency virus type 1 (HIV-1, causative agent of AIDS) infection represents a major challenge in antiviral therapeutics. Many difficulties are associated with the treatment, including toxicity, resistance and high costs. Taking this into account, research for novel compounds able to overcome these limitations is needed. Sulfated polysaccharides appear to be interesting, given their abundance as components of seaweeds. Herein, a series of fractions obtained from the brown seaweed Adenocystis utricularis was analysed for in vitro anti-HIV-1 activity. These fractions, which have anti-herpes simplex virus activity, were determined previously to belong to the family of fucoidans, sulfated polysaccharides obtained from the cell walls of brown seaweeds. Assays in human PBMC primary cell culture demonstrated that two of the five fractions analysed had potent anti-HIV-1 activity both against WT and drug-resistant HIV-1 strains. For active fractions, it was also shown that the inhibitory effect was not due to an inactivating effect on the viral particle (i.e. no virucidal activity was detected) but rather to a blockade of early events of viral replication. Given these encouraging results, these seaweed-derived fractions appear as good candidates for further studies on their potential for in vivo therapy and/or prophylaxis of HIV-1 infection.Fil: Trinchero Hernandez, Juan Sebastian. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Cátedra de Microbiología, Parasitología e Inmunología; ArgentinaFil: Ponce, Nora Marta Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro. Departamento de Farmacia. Cátedra de Farmacognosia; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Córdoba, Osvaldo León. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; ArgentinaFil: Flores, Maria Lujan. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro. Departamento de Farmacia. Cátedra de Farmacognosia; ArgentinaFil: Pampuro, Sandra Esther. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Cátedra de Microbiología, Parasitología e Inmunología; ArgentinaFil: Stortz, Carlos Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Salomon, Horacio Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Cátedra de Microbiología, Parasitología e Inmunología; ArgentinaFil: Turk, Gabriela Julia Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Cátedra de Microbiología, Parasitología e Inmunología; Argentin

Antiretroviral Resistance among HIV Type 1-Infected Women First Exposed to Antiretrovirals during Pregnancy: Plasma versus PBMCs

Resistance-associated mutations (RAMs) in plasma samples from HIV-1-infected women who received antiretroviral (ARV) prophylaxis during pregnancy was assessed and correlated with the detection of RAMs in peripheral blood mononuclear cells (PMBCs). The study population was composed of HIV-1-infected women enrolled in a prospective cohort study in Latin America and the Caribbean (NISDI Perinatal Study) as of March 1, 2005, who were diagnosed with HIV-1 infection during the current pregnancy, who received ARVs during pregnancy for prevention of mother-to-child transmission of HIV-1, and who were followed through at least the 6–12 week postpartum visit. Plasma samples collected at enrollment during pregnancy and at 6–12 weeks postpartum were assayed for RAMs. Plasma results were compared to previously described PBMC results from the same study population. Of 819 enrolled subjects, 197 met the eligibility criteria. Nucleic acid amplification was accomplished in 123 plasma samples at enrollment or 6–12 weeks postpartum, and RAMs were detected in 22 (17.9%; 95%CI: 11.7–25.9%). Previous analyses had demonstrated detection of RAMs in PBMCs in 19 (16.1%). There was high concordance between RAMs detected in plasma and PBMC samples, with only eight discordant pairs. The prevalence of RAMs among these pregnant, HIV-1-infected women is high (>15%). Rates of detection of RAMs in plasma and PBMC samples were similar

Analysis of HIV Type 1 BF Recombinant Sequences from South America Dates the Origin of CRF12_BF to a Recombination Event in the 1970s

HIV-1 epidemics in South America are believed to have originated in part from the subtype B epidemic initiated in the Caribbean/North America region. However, circulation of BF recombinants in similar proportions was extensively reported. Information currently shows that many BF recombinants share a recombination structure similar to that found in the CRF12_BF. In the present study, analyzing a set of 405 HIV sequences, we identified the most likely origin of the BF epidemic in an early event of recombination. We found that the subtype B epidemics in South America analyzed in the present study were initiated by a founder event that occurred in the early 1970s, a few years after the introduction of these strains in the Americas. Regarding the F/BF recombinant epidemics, by analyzing a subtype F genomic segment within the viral gene gag present in the majority of the BF recombinants, we found evidence of a geographic divergence very soon after the introduction of subtype F strains in South America. Moreover, through analysis of a subtype B segment present in all the CRF12_BF-like recombination structure, we estimated the circulation of the subtype B strain that gave rise to that recombinant structure around the same time period estimated for the introduction of subtype F strains. The HIV epidemics in South America were initiated in part through a founder event driven by subtype B strains coming from the previously established epidemic in the north of the continent. A second introduction driven by subtype F strains is likely to have encountered the incipient subtype B epidemic that soon after their arrival recombined with them, originating the BF epidemic in the region. These results may explain why in South America the majority of F sequences are found as BF recombinants