Sandra Pampuro

Discrepant results in the interpretation of HIV-1 drug-resistance genotypic data among widely used algorithms.

The aim of this study was to assess the concordance on the interpretation of HIV‐1 drug‐resistance genotypic data by three widely used algorithms: Stanford University Database (SU), TruGene (Visible Genetics, Canada) (VG) and VirtualPhenotype (Virco, Belgium) (VP).

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. Copyright

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

ABSTRACT 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.

Cytotoxic and DNA interaction activities of extracts from medicinal plants used in Argentina

Eight crude extracts from seven Argentine plants with cancer-related ethnobotanical uses have been subjected to a bioscreening study to detect cytotoxic activity. The plants studied were: Aristolochia triangularis, Baccharis grisebachii, Bolax gummifera, Eupatorium hecatanthum, Erythrina crista-galli, Pterocaulon polystachium and Salpichroa origanifolia. Crown gall tumour inhibition, DNA interaction and cytotoxicity towards KB cells were assayed using the potato disc, the DNA-methyl green (DNA-MG) and the KB cells cytotoxicity bioassays respectively. The results obtained indicate that A. triangularis (ED50=47 microg/ml), B. gummifera (ED50=32 microg/ml) and E. hecatanthum (ED50=35 microg/ml) contained cytotoxic compounds against KB cells. All of the plants studied inhibited the growth of crown gall tumours, showing correlation between the experimental data and the uses reported for these plants. Moreover, the results obtained for the extracts of E. hecatanthum and P. polystachium indicate the presence of compounds that interact with DNA (48 and 22% of absorbance decrease, respectively). The results obtained suggest that cytotoxicity could play an important role in the activities claimed for the plants under study.

Drug resistance among HIV-infected pregnant women receiving antiretrovirals for prophylaxis.

Objective:To quantify primary resistance mutations (PRMs) among HIV-1-infected women receiving antiretroviral therapy (ART) for prevention of mother-to-child transmission (MTCT). Methods:Peripheral blood mononuclear cell samples from HIV-1-infected women enrolled in a prospective cohort study in Argentina, the Bahamas, Brazil, and Mexico (NISDI Perinatal Study) were assayed for PRMs. Eligible women were those enrolled by March 2005 and diagnosed with HIV-1 infection during the current pregnancy, and who received ART for MTCT prophylaxis and were followed for 6–12 weeks postpartum. Results:Of 819 women, 198 met the eligibility criteria. At enrollment, 98% were asymptomatic, 62% had plasma viral load < 1000 copies/ml, 53% had CD4+ cell count ≥ 500 cells/μl, and 78% were ART-exposed (mean duration, 8.0 weeks; 95% confidence interval, 7.1–8.9). The most complex ART regimen during pregnancy was usually (81%) a three-drug regimen [two nucleoside reverse transcriptase inhibitors (NRTIs) + one protease inhibitor or two NRTIs + one non-nucleoside reverse transcriptase inhibitor). PRMs were observed in samples from 19 (16%) of 118 women that were amplifiable at one or both time points [11/76 (14%) at enrollment; 14/97 (14%) at 6–12 weeks]. The occurrence of PRMs was not associated with clinical, immunological, or virological disease stage at either time point, whether ART-naive versus exposed at enrollment, or the most complex or number of antiretroviral drug regimens received during pregnancy (P > 0.1). Of 55 women with amplifiable samples at both time points, PRMs were detected in 11 samples (20%). Conclusions:PRMs occurred among 16.1% of relatively healthy HIV-1-infected mothers from Latin American and Caribbean countries receiving MTCT prophylaxis.

Drug-resistance surveillance among newly HIV-1 diagnosed individuals in Buenos Aires, Argentina

Objective:Our objective was to estimate primary resistance in an urban setting in a developing country with a long history of antiretroviral delivery and high coverage levels. Design:We carried out a resistance surveillance study according to WHO HIV-Resistance Guidelines. Methods:Blood samples were collected from 323 drug-naive HIV-1 infected individuals diagnosed at two HIV voluntary counselling and testing centers in Buenos Aires. Viral-load, CD4 cell counts and detuned assays were performed on all samples. The pol gene was sequenced and the resistance profile determined. Phylogenetic analysis was performed by neighbor-joining trees and bootscanning analysis. Results:We found that 12 (4.2%) of the 284 samples sequenced harbored primary resistance mutations, of which K103N, M41L and V108I were most prevalent. Phylogenetic analysis revealed evidence for the transmission of the K103N mutation among the drug-naive population. The proportion of recent infections identified by the detuned assay was 10.1%. Conclusions:Levels of primary resistance in Buenos Aires are still low, despite a long history of ARV delivery and high coverage levels.

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-naïve 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 80s. 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.

Inhibitory effect of medicinal herbs against RNA and DNA viruses

Fifteen Argentine medicinal plants were tested for their antiviral activity in vitro against herpes simplex viruses types 1 and 2 (HSV-1 and 2), bovine viral diarrhoea virus type 1 (BVDV-1), influenza virus type A (Inf A) and human immunodeficiency virus type 1 (HIV-1). Antiviral activity was evaluated by a reduction in cytopathic effect, plaque-forming units and p24 HIV-1 antigen. The Selective Index of the active extract (SIextract =CC50 extract/EC50 extract) of Coronopus didymus (SIextract=110.7), Juglans australis (SIextract=8.1) and Lippia alba (SIextract=19.2) against BVDV-1, HSV-1 and influenza A virus, respectively, justify a further analysis. None of the seven plants assayed against HIV-1 displayed any antiviral activity. The results of this study justify the continuing isolation and characterization of the antiviral components present.

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.