Verónica Briz

HIV tropism: diagnostic tools and implications for disease progression and treatment with entry inhibitors.

CCR5 and CXCR4 are the major chemokine coreceptors used by HIV to enter into human cells [1–3]. Based on this co-receptor usage, a new HIV classification was established in 1998, i.e., CCR5-tropic (R5), CXCR4-tropic (X4), or dual tropic (R5/X4) HIV-1 strains [4]. Ten years earlier, Tersmette et al. identified a relationship between viral phenotype (i.e., non-syncytium-inducing, NSI or syncytium-inducing, SI) and the virulence of HIV strains [5]. We now know that, in vitro, R5 viruses usually correspond to NSI on T-cell lines and are able to replicate in monocyte–macrophages (M-tropic), all features that previously had been linked to less virulent strains. In contrast, X4 strains are SI on T-cell lines and replicate preferentially on T lymphocytes (T-tropic), all characteristics of more pathogenic virus strains [5–8]. On the basis of these findings, it is clear that HIV co-receptor usage may be associated with disease progression.

Correlation between a phenotypic assay and three bioinformatic tools for determining HIV co-receptor use.

The predictive value of three genotypic methods to determine HIV-1 co-receptor usage was assessed in 83 plasma specimens taking as reference the results obtained using a recombinant phenotypic assay (Phenoscript). The best concordance was found for webPSSM, followed by geno2pheno and wetcat (85.9, 71.8 and 70.5%, respectively). Less than 5.1% of phenotypic X4 viruses were missed by genotypic tools. The genotypic prediction of HIV-1 co-receptor usage can thus assist therapeutic decisions for using CCR5 antagonists.

Raltegravir and etravirine are active against HIV type 1 group O.

Abstract The activity of raltegravir and etravirine was assessed in vitro in HIV-1 group O isolates. Despite the presence of some natural polymorphisms associated with resistance to raltegravir (V72I, L74I, S153A, V201I, and T206S) and etravirine (G190A), both drugs showed significant antiviral activity. Subsequently, the clinical benefit was shown in an HIV-1 group O-infected individual in whom enfuvirtide was replaced by raltegravir. Therefore, individuals infected with HIV-1 group O might benefit from raltegravir and/or etravirine therapy.

Successful rescue therapy with darunabir (TMC114) in HIV-infected patients who have failed several ritonavir-boosted protease inhibitors

Darunabir, formerly TMC114, is a new protease inhibitor (PI) under clinical development designed to be active against HIV strains resistant to currently available PI. The virological and immunological response to ritonavir-boosted darunabir was assessed in four heavily antiretroviral-experienced patients who had failed enfuvirtide and two or more previous ritonavir-boosted PI regimens, including tipranavir in one instance. All four patients reached undetectable plasma HIV-RNA levels within 8 weeks of therapy and experienced significant CD4 cell count gains.

Potent and sustained antiviral response of raltegravir-based highly active antiretroviral therapy in HIV type 1-infected children and adolescents.

Background: There are pediatric patients receiving many highly active antiretroviral therapy (HAART) regimens entailing drug resistance mutations that complicate HAART effective therapies. Methods: This was a multicenter retrospective study of 19 multidrug-resistant children and adolescents enrolled from July 2007 to October 2009. Patients were nonresponders because no reduction in HIV type 1 (HIV-1) RNA to undetectable levels was observed during their previous antiretroviral treatment history. The long-term effectiveness of raltegravir (RAL)-based salvage therapy was assessed through a longitudinal analysis of immunologic, virologic, and clinical status of the patients. Results: Median age was 16.0 (15.0–18.0) years. At baseline, median HIV-1 RNA was 10,000 (4.0 log10 copies/mL) (interquartile range [IQR]: 4300–83,000), and median CD4+T-cell count was 329 (18.2% cells/&mgr;L) (IQR: 175–452). The backbone regimen included at least 1 fully active drug in 17/19 (89%) patients. Median follow-up with HAART including RAL was 80.1 weeks (IQR: 49.4–96.4): 16/19 (84%) exposed for >120 weeks and 6/19 (32%) >100 weeks. After RAL-based therapy, 4/19 (21%) patients achieved HIV-1 RNA <400 copies and 13/17 (68%) reached HIV-1 RNA <50 copies: 6 (32%) within the first month and 7 (37%) within the first 4 months. CD4+T-cell recovery (70% to 90% of the baseline values) was observed in 17/19 (89%) patients. No deaths, AIDS-defining illnesses, or symptoms of severe intolerance were recorded. Only 2 patients experienced mild-moderate short-term skin rash. Two (11%) patients had sustained and optimum adherence to HAART. No patients showed resistance mutations to RAL after follow-up. Conclusions: We observed a sustained antiviral response and improved immunologic indices in multidrug-resistant pediatric patients, most of whom had received RAL as part of salvage regimens with at least 1 fully active drugs.

Etravirine-based highly active antiretroviral therapy in HIV-1-infected paediatric patients

We evaluated the efficacy, safety and tolerability of etravirine in paediatric patients vertically infected with HIV‐1.

Outside-binding site mutations modify the active site's shapes in neuraminidase from influenza A H1N1†

The recent occurrence of 2009 influenza A (H1N1) pandemic as well as others has raised concern of a far more dangerous outcome should this virus becomes resistant to current drug therapies. The number of clinical cases that are resistant to oseltamivir (Tamiflu®) is larger than the limited number of neuraminidase (NA) mutations (H275Y, N295S, and I223R) that have been identified at the active site and that are associated to oseltamivir resistance. In this study, we have performed a comparative analysis between a set of NAs that have the most representative mutations located outside the active site. The recently crystallized NA-oseltamivir complex (PDB ID: 3NSS) was used as a wild-type structure. After selecting the target NA sequences, their three-dimensional (3D) structure was built using 3NSS as a template by homology modeling. The 3D NA models were refined by molecular dynamics (MD) simulations. The refined models were used to perform a docking study, using oseltamivir as a ligand. Furthermore, the docking results were refined by free-energy analysis using the MM-PBSA method. The analysis of the MD simulation results showed that the NA models reached convergence during the first 10 ns. Visual inspection and structural measures showed that the mutated NA active sites show structural variations. The docking and MM-PBSA results from the complexes showed different binding modes and free energy values. These results suggest that distant mutations located outside the active site of NA affect its structure and could be considered to be a new source of resistance to oseltamivir, which agrees with reports in the clinical literature.

NS3 Resistance-Associated Variants (RAVs) in Patients Infected with HCV Genotype 1a in Spain.

Background Resistance-associated variants have been related to treatment failure of hepatitis C virus (HCV) therapy with direct-acting antiviral drugs. The aim of our study was to analyze the prevalence of clinically relevant resistance-associated variants within NS3 in patients infected with HCV genotype 1a (GT1a) in Spain. Methods We performed a cross-sectional study on 2568 patients from 115 hospitals throughout Spain (2014–2015). The viral NS3 protease gene was amplified by nested polymerase chain reaction and sequenced by Sanger sequencing using an ABI PRISM 377 DNA sequencer. Additionally, clade information for genotype 1a was obtained by using the software geno2pheno (http://hcv.geno2pheno.org/). Results In total, 875 out of 2568 samples were from human immunodeficiency virus (HIV)/HCV-coinfected patients. Q80K was the main RAV found in our patients (11.1%) and the rest of the resistance-associated variants had a lower frequency, including S122G (6.23%), T54S (3.47%), V55A (2.61%), and V55I (2.15%), which were among the most frequent after Q80K. Overall, 286 samples had the Q80K polymorphism (11.1%) and 614 (23.9%) were GT1a clade I. HIV/HCV-coinfected patients had a higher frequency of Q80K and GT1a clade I than HCV-monoinfected patients (12.9% vs. 9.6% [p = 0.012] and 28.5% vs. 21.4% [p<0.001], respectively). Both the prevalence of Q80K and GT1a clade I were not uniform throughout the country (p<0.001), which ranged from 7.3%-22.2% and 15.7%-42.5%, respectively. The frequency of the Q80K polymorphism was far higher in patients infected with GT1a clade I than in patients infected with GT1a clade II (41.5% vs. 1.6%; p<0.001). Conclusions The prevalence of most resistance-associated variants in NS3 was low in patients infected with HCV GT1a in Spain, except for Q80K (11.1%), which was also notably higher in HIV/HCV-coinfected patients. The vast majority of Q80K polymorphisms were detected in GT1a clade I.

Predictors of attrition and immunological failure in HIV- 1 patients on highly active antiretroviral therapy from different healthcare settings in Mozambique

In Mozambique, the evaluation of retention in HIV care and ART programmes is limited. To assess rate and predictors of attrition (no retention in care) and HAART effectiveness in HIV-1 infected patients who pay for medication and laboratory testing in Mozambique, we conducted a multicenter survey of HIV-1-infected patients who started HAART during 2002–2006. Cox proportional hazard models were used to assess risk of attrition and of therapy failure. Overall, 142 patients from 16 healthcare centers located in the capital city Maputo were followed-up for 22.2 months (12.1–46.7). The retention rate was 75%, 48% and 37% after one, two and three years, respectively. Risk of attrition was lower in patients with higher baseline CD4 count (P = 0.022) and attending healthcare center 1 (HCC1) (P = 0.013). The proportion of individuals with CD4 count ≤200 cells/µL was 55% (78/142) at baseline and decreased to 6% (3/52) at 36 months. Among the patients with available VL, 86% (64/74) achieved undetectable VL levels. The rate of immunologic failure was 17.2% (95% CI: 12.6–22.9) per 100 person-years. Risk of failure was associated to higher baseline CD4 count (P = 0.002), likely reflecting low adherence levels, and decreased with baseline VL ≥10,000 copies/mL (P = 0.033). These results suggest that HAART can be effective in HIV-1 infected patients from Mozambique that pay for their medication and laboratory testing. Further studies are required to identify the causes for low retention rates in patients with low CD4 counts and to better understand the association between healthcare setting and attrition rate.

Carbosilane dendrimers as carriers of siRNA

Despite the enormous possibilities of RNAi, there still exist many problems that need to be addressed. Obstacles in delivery, target cell transfection, stability/degradation, transient activity, secondary effects, toxicity caused by the delivery vector, and resistance all hinder the path of carrying out in vivo experiments with RNAi and further developing RNAi as a new therapy for clinical use. Notwithstanding, the majority of research that uses RNAi depends on a delivery vector of some kind. This review offers a brief overview of the current status of carbosilane dendrimers as siRNA delivery vectors.