Parenteral platforms for tunable, long-acting administration of a highly hydrophobic antiretroviral drug

GSK2838232 (GSK8232) is a second-generation maturation inhibitor (MI) developed for the treatment of HIV with excellent broad-spectrum virological profiles. The compound has demonstrated promising clinical results as an orally administered agent. Additionally, the compound's physical and pharmacological properties present opportunities for exploitation as long-acting parenteral formulations. Despite unique design constraints including solubility and dose of GSK8232, we report on three effective tunable drug delivery strategies: active pharmaceutical ingredient (API) suspensions, ionic liquids, and subdermal implants. Promising sustained drug release profiles were achieved in rats with each approach. Additionally, we were able to tune drug release rates through a combination of passive and active strategies, broadening applicability of these formulation approaches beyond GSK8232. Taken together, this report is an important first step to advance long-acting formulation development for critical HIV medicines that do not fit the traditional profile of suitable long-acting candidates.

Acquired HIV-1 Protease Conformational Flexibility Associated with Lopinavir Failure May Shape the Outcome of Darunavir Therapy after Antiretroviral Therapy Switch

Understanding the underlying molecular interaction during a therapy switch from lopinavir (LPV) to darunavir (DRV) is essential to achieve long-term virological suppression. We investigated the kinetic and structural characteristics of multidrug-resistant South African HIV-1 subtype C protease (HIV-1 PR) during therapy switch from LPV to DRV using enzyme activity and inhibition assay, fluorescence spectroscopy, and molecular dynamic simulation. The HIV-1 protease variants were from clinical isolates with a combination of drug resistance mutations; MUT-1 (M46I, I54V, V82A, and L10F), MUT-2 (M46I, I54V, L76V, V82A, L10F, and L33F), and MUT-3 (M46I, I54V, L76V, V82A, L90M, and F53L). Enzyme kinetics analysis shows an association between increased relative resistance to LPV and DRV with the progressive decrease in the mutant HIV-1 PR variants' catalytic efficiency. A direct relationship between high-level resistance to LPV and intermediate resistance to DRV with intrinsic changes in the three-dimensional structure of the mutant HIV-1 PR as a function of the multidrug-resistance mutation was observed. In silico analysis attributed these structural adjustments to the multidrug-resistance mutations affecting the LPV and DRV binding landscape. Though DRV showed superiority to LPV, as a lower concentration was needed to inhibit the HIV-1 PR variants, the inherent structural changes resulting from mutations selected during LPV therapy may dynamically shape the DRV treatment outcome after the therapy switch.

Multidomain drug delivery systems of β-casein micelles for the local oral co-administration of antiretroviral combinations

The antiretroviral (ARV) cocktailrevolved the treatment of the human immunodeficiency virus (HIV) infection. Drug combinations have been also tested to treat other infectious diseases, including the recentcoronavirus disease 2019 (COVID-19) outbreak. To simplify administration fixed-dose combinationshave been introduced, however, oral anti-HIV therapy still struggles with low oral bioavailability of many ARVs.This work investigated the co-encapsulation of two clinically relevant ARV combinations,tipranavir (TPV):efavirenz (EFV) anddarunavir (DRV):efavirenz (EFV):ritonavir (RTV),within the core of β-casein (bCN) micelles. Encapsulation efficiency in both systems was ~100%. Cryo-transmission electron microscopy and dynamic light scattering of the ARV-loaded colloidaldispersions indicatefull preservation of the spherical morphology, and x-ray diffraction confirm that the encapsulated drugs are amorphous. To prolong the physicochemical stabilitythe formulations were freeze-driedwithout cryo/lyoprotectant, and successfully redispersed, with minor changes in morphology.Then, theARV-loaded micelles were encapsulated within microparticles of Eudragit® L100, which prevented enzymatic degradation and minimized drug release under gastric-like pH conditionsin vitro. At intestinal pH, the coating polymer dissolved and released the nanocarriers and content. Overall, our results confirm the promise of this flexible and modular technology platform for oral delivery of fixed dose combinations.

Phase I evaluation of the safety, tolerability, and pharmacokinetics of GSK3640254, a next-generation HIV-1 maturation inhibitor

Despite advances in HIV-1 management with antiretroviral therapy, drug resistance and toxicities with multidrug regimens can result in treatment failure. Hence, there is a continuing demand for antiretroviral agents (ARVs) with novel mechanisms of action. Maturation inhibitors inhibit HIV-1 replication via a unique mechanism of action and can be combined with other ARVs. Two phase I randomized clinical trials were conducted for a maturation inhibitor, GSK3640254, to determine safety, pharmacokinetics (NCT03231943), and relative bioavailability (NCT03575962) in healthy adults. The first trial was conducted in two parts. Part 1 was conducted in a two-cohort, interlocking, eight-period fashion in 20 participants with single ascending doses of GSK3640254 (1-700 mg) or placebo. In Part 2, 58 participants were randomized to receive GSK3640254 (n = 44) or placebo (n = 14). Four participants reported adverse events (AEs) leading to study discontinuation, with one adverse drug reaction (maculopapular rash). There was no relationship between frequency or severity of AEs and dose. Pharmacokinetic assessments showed that GSK3640254 was slowly absorbed, with time to maximum concentration (tmax) occurring between 3.5 and 4 hours and half-life of ~24 hours. In the relative bioavailability study of GSK3640254 mesylate salt vs bis-hydrochloride salt capsules in 14 healthy adults, the mesylate salt performed slightly better than the bis-hydrochloride formulation (12%-16% increase in area under the concentration-time curve and maximum concentration); tmax (5 hours) was similar between the formulations. Initial pharmacokinetic and safety data from these healthy-participant studies informed further development of GSK3640254 for once-daily dosing for the treatment of HIV-1 infection.

Thorough evaluation of OECD principles in modelling of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine derivatives using QSARINS

The human immunodeficiency virus is a lethal pathology considered as a worldwide problem. The search for new strategies for the treatment of this disease continues to be a great challenge in the scientific community. In this study, a series of 107 derivatives of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine, previously evaluated experimentally against HIV-I reverse transcriptase, was used to model antiretroviral activity. A model of linear regression, implemented in the QSARINS software, was developed with a genetic algorithm for variable selection. The fit of its parameters was good and exhaustive validation, according to the OECD regulatory principles, was performed. Also, the applicability domain was established. In addition, its robustness (r ² = 0.84), stability (Q ² _LOO = 0.81; Q ² _LMO = 0.80) and good predictive power (r ² _EXT = 0.85) is proved. So, it was used to predict the antiretroviral activity of eight compounds obtained by rational drug design. Finally, it can be affirmed that the proposed tools allow the rapid and economic identification of potential antiretroviral drugs.

Novel delivery based anionic linear globular dendrimerg2-zidovudine nano-conjugate significantly decreased retroviral activity

Human diseases like viral organisms for example, hepatitis, HIV and etc., attack the health and caused large mortality in populations by many years. So finding novel delivery vehicles based antiviral drugs employing nano-materials is of high universal interest. In current approach a very biocompatible biodegradable nano-biopolymer anionic linear globular dendrimer second generation G2 was elaborately conjugated to a well-known anti-HIV drug Azidovudine and thereafter was characterized by different analytical techniques like AFM, Zeta sizer, 1HNMR, FTIR and LC-Mass spectroscopy. Then, Anionic Linear Globular DendrimerG2-Zidovudine Nano-Conjugate was assessed on human normal cells (toxicity assay by XTT test) and also HIV cell model and the results showed that Anionic Linear Globular DendrimerG2-Zidovudine Nano-Conjugate Significantly Decreased Retroviral Activity without any human cell toxicity respectively. Based on current experimental data such nano-compositions is proposed for further in vivo anti-HIV assays as well.

Spatial distribution of elvitegravir and tenofovir in rat brain tissue: Application of matrix-assisted laser desorption/ionization mass spectrometry imaging and liquid chromatography/tandem mass spectrometry

RATIONALE

The complexity of central nervous system (CNS) drug delivery is the main obstacle with the blood-brain barrier (BBB) known to restrict access of most pharmaceutical drugs into the brain. Mass spectrometry imaging (MSI) offers possibilities for studying drug deposition into the CNS.

METHODS

The deposition and spatial distribution of the two antiretroviral drugs elvitegravir and tenofovir in the brain were investigated in healthy female Sprague-Dawley rats following a single intraperitoneal administration (50 mg/kg). This was achieved by the utilization of quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) and matrix-assisted laser desorption/ionization (MALDI) MSI.

RESULTS

LC/MS/MS showed that elvitegravir has better BBB penetration, reaching maximum concentration in the brain (C_max brain) of 976.5 ng/g. In contrast, tenofovir displayed relatively lower BBB penetration, reaching C_max brain of 54.5 ng/g. MALDI-MSI showed the heterogeneous distribution of both drugs in various brain regions including the cerebral cortex.

CONCLUSIONS

LC/MS/MS and MALDI-MSI provided valuable information about the relative concentration and the spatial distribution of the two common antiretroviral drugs. This study has also shown the capability of MALDI-MSI for direct visualization of pharmaceutical drugs in situ.

Novel Antiretroviral Structures from Marine Organisms

In spite of significant advancements and success in antiretroviral therapies directed against HIV infection, there is no cure for HIV, which scan persist in a human body in its latent form and become reactivated under favorable conditions. Therefore, novel antiretroviral drugs with different modes of actions are still a major focus for researchers. In particular, novel lead structures are being sought from natural sources. So far, a number of compounds from marine organisms have been identified as promising therapeutics for HIV infection. Therefore, in this paper, we provide an overview of marine natural products that were first identified in the period between 2013 and 2018 that could be potentially used, or further optimized, as novel antiretroviral agents. This pipeline includes the systematization of antiretroviral activities for several categories of marine structures including chitosan and its derivatives, sulfated polysaccharides, lectins, bromotyrosine derivatives, peptides, alkaloids, diterpenes, phlorotannins, and xanthones as well as adjuvants to the HAART therapy such as fish oil. We critically discuss the structures and activities of the most promising new marine anti-HIV compounds.

Cyclodextrin solubilization and complexation of antiretroviral drug lopinavir: In silico prediction; Effects of derivatization, molar ratio and preparation method

Lopinavir (LPV) is currently used in combination with ritonavir for the clinical management of HIV infections due to its limited oral bioavailability. Herein, we report the application of an in silico method to study cyclodextrin (CyD) host-guest molecular interaction with LPV for the rational selection of the best CyD for developing a CyD based LPV delivery system. The predicted CyD, a (2-hydroxy)propyl-gamma derivative with high degree of substitution (HP17-γ-CyD) was synthesized and comparatively evaluated with γ-CyD and the commercially available HP-γ-CyD. All complexes were prepared by supercritical assisted spray drying (SASD) and co-evaporation (CoEva) at molar ratios (1:1 and 1:2); and afterwards fully characterized. Results indicate a higher LPV amorphization and solubilization ability of HP17-γ-CyD. The SASD processing technology also enhanced LPV solubilization and release from complexes. The application of in silico methodologies is a feasible approach for the rational and/or deductive development of CyD drug delivery systems.

Multifunctional Nanotherapeutics for the Treatment of neuroAIDS in Drug Abusers

HIV and substance abuse plays an important role in infection and disease progression. Further, the presence of persistent viral CNS reservoirs makes the complete eradication difficult. Thus, neutralizing the drug of abuse effect on HIV-1 infectivity and elimination of latently infected cells is a priority. The development of a multi-component [antiretroviral drugs (ARV), latency reactivating agents (LRA) and drug abuse antagonist (AT)] sustained release nanoformulation targeting the CNS can overcome the issues of HIV-1 cure and will help in improving the drug adherence. The novel magneto-liposomal nanoformulation (NF) was developed to load different types of drugs (LRAs, ARVs, and Meth AT) and evaluated for in-vitro and in-vivo BBB transmigration and antiviral efficacy in primary CNS cells. We established the HIV-1 latency model using human astrocyte cells (HA) and optimized the dose of LRA for latency reversal, Meth AT in in-vitro cell culture system. Further, PEGylated magneto-liposomal NF was developed, characterized for size, shape, drug loading and BBB transport in-vitro. Results showed that drug released in a sustained manner up to 10 days and able to reduce the HIV-1 infectivity up to ~40-50% (>200 pg/mL to <100 pg/mL) continuously using single NF treatment ± Meth treatment in-vitro. The magnetic treatment (0.8 T) was able to transport (15.8% ± 5.5%) NF effectively without inducing any toxic effects due to NF presence in the brain. Thus, our approach and result showed a way to eradicate HIV-1 reservoirs from the CNS and possibility to improve the therapeutic adherence to drugs in drug abusing (Meth) population. In conclusion, the developed NF can provide a better approach for the HIV-1 cure and a foundation for future HIV-1 purging strategies from the CNS using nanotechnology platform.

Deciphering the targets of retroviral protease inhibitors in Plasmodium berghei

Retroviral protease inhibitors (RPIs) such as lopinavir (LP) and saquinavir (SQ) are active against Plasmodium parasites. However, the exact molecular target(s) for these RPIs in the Plasmodium parasites remains poorly understood. We hypothesised that LP and SQ suppress parasite growth through inhibition of aspartyl proteases. Using reverse genetics approach, we embarked on separately generating knockout (KO) parasite lines lacking Plasmepsin 4 (PM4), PM7, PM8, or DNA damage-inducible protein 1 (Ddi1) in the rodent malaria parasite Plasmodium berghei ANKA. We then tested the suppressive profiles of the LP/Ritonavir (LP/RT) and SQ/RT as well as antimalarials; Amodiaquine (AQ) and Piperaquine (PQ) against the KO parasites in the standard 4-day suppressive test. The Ddi1 gene proved refractory to deletion suggesting that the gene is essential for the growth of the asexual blood stage parasites. Our results revealed that deletion of PM4 significantly reduces normal parasite growth rate phenotype (P = 0.003). Unlike PM4_KO parasites which were less susceptible to LP and SQ (P = 0.036, P = 0.030), the suppressive profiles for PM7_KO and PM8_KO parasites were comparable to those for the WT parasites. This finding suggests a potential role of PM4 in the LP and SQ action. On further analysis, modelling and molecular docking studies revealed that both LP and SQ displayed high binding affinities (-6.3 kcal/mol to -10.3 kcal/mol) towards the Plasmodium aspartyl proteases. We concluded that PM4 plays a vital role in assuring asexual stage parasite fitness and might be mediating LP and SQ action. The essential nature of the Ddi1 gene warrants further studies to evaluate its role in the parasite asexual blood stage growth as well as a possible target for the RPIs.

Removal of antiretroviral drugs stavudine and zidovudine in water under UV254 and UV254/H2O2 processes: Quantum yields, kinetics and ecotoxicology assessment

The concentration of antiretroviral drugs in wastewater treatment plants (WWTP) effluents and surface waters of many countries has increased significantly due to their widespread use for HIV treatment. In this study, the removal of stavudine and zidovudine under UV₂₅₄ photolysis or UV₂₅₄/H₂O₂ was investigated in a microcapillary film (MCF) photoreactor, using minimal water samples quantities. The UV₂₅₄ quantum yield of zidovudine, (2.357 ± 0.0589)·10^-2 mol ein^-1 (pH 4.0-8.0), was 28-fold higher that the yield of stavudine (8.34 ± 0.334)·10^-4 mol ein^-1 (pH 6.0-8.0). The second-order rate constant k_OH,iof reaction of hydroxyl radical with the antiretrovirals (UV₂₅₄/H₂O₂ process) were determined by kinetics modeling: (9.98 ± 0.68)·10⁸ M^-1 s^-1 (pH 4.0-8.0) for zidovudine and (2.03 ± 0.18)·10⁹ M^-1 s^-1 (pH 6.0-8.0) for stavudine. A battery of ecotoxicological tests (i.e. inhibition growth, bioluminescence, mutagenic and genotoxic activity) using bacteria (Aliivibrio fischeri, Salmonella typhimurium), crustacean (Daphnia magna) and algae (Raphidocelis subcapitata) revealed a marked influence of the UV dose on the ecotoxicological activity. The UV₂₅₄/H₂O₂ treatment process reduced the ecotoxicological risk associated to direct photolysis of the antiretrovirals aqueous solutions, but required significantly higher UV₂₅₄ doses (≥2000 mJ cm^-2) in comparison to common water UV disinfection processes.

A Search for Dual Action HIV-1 Reverse Transcriptase, Bacterial RNA Polymerase Inhibitors

Using molecular modeling approach, potential antibacterial agents with triazole core were proposed. A moderate to weak level of antibacterial activity in most of the compounds have been observed, with best minimal inhibitory concentration (MIC) value of 0.003 mg/mL, as shown by the 15 against S. epidermidis. Studied compounds were also submitted to the antifungal assay. The best antifungal activity was detected for 16 with MIC at 0.125 and 0.25 mg/mL against C. albicans and C. parapsilosis, respectively.

Multiple Lipid Nanoparticles (MLN), a New Generation of Lipid Nanoparticles for Drug Delivery Systems: Lamivudine-MLN Experimental Design

PURPOSE

An optimized methodology for the development of a new generation of lipid nanoparticles, the multiple lipid nanoparticles (MLN) is described. MLN have characteristics between nanostructured lipid carriers (NLC) and multiple emulsions (W/O/W), but without the outer aqueous phase.

METHODS

The production is based on a hot homogenization method combined with high shear and ultrasonication. The antiretroviral agent lamivudine (3TC), was loaded in the MLN. For comparison purposes, NLC-3TC formulation was also developed and physico-chemically characterized by the same parameters as MLN-3TC. The development and optimization of MLN and NLC formulations were supported by a Quality by Design (QbD) approach.

RESULTS

The MLN-3TC formulation exhibited a size of about 450 nm, polydispersity <0.3 and negative zeta potential > -20 mV. Furthermore, the morphology assessed by TEM showed a structure with multiples aqueous vacuoles. MLN-3TC was physically stable for at least 45 days, had low cytotoxicity and drug release studies showed a sustained and controlled release of 3TC under gastric and plasma-simulated conditions (at pH 7.4 for about 45 h).

CONCLUSIONS

The optimized formulations present suitable profiles for oral administration. Overall, the results reveal that MLN present higher loading capacity and storage stability than NLC.

STABILITY INDICATIVE HPLC DETERMINATION OF RELATED SUBSTANCES AND IDENTIFICATION OF POTENTIAL DEGRADANTS USING LC-MS IN TRIPLE COMBINATION ANTIRETROVIRAL TABLETS

A rapid stability indicating liquid chromatography method was developed and validated for the simultaneous quantitation of related substances of antiretrovirals in combined oral dosage formulation. Separation was achieved using a Waters, Xterra RP-18 column (250 x 4.6 mm) with a mobile phase containing a gradient mixture of sodium acetate trihydrate solution and acetonitrile with a flow rate of 1 mL/min, detec- tion at 254 nm. A simple preparative and LC-MS method were applied for the isolation and identification of degradation products. The active drugs were subjected to stress studies and significant degradation was observed. The spectral purity of the active drugs was determined to establish the stability indicating power of the developed method. The developed chromatographic method was validated as per ICH guidelines and is capable to identify and quantify all the 17 impurities at a level of 0.01 and 0.03%, respectively, with respect to test concentration. The wide range of linearity and good resolution imply that the method is suitable for routine quantification of related substances as well as for the assay of the actives.

Simultaneous quantification of tenofovir, emtricitabine, rilpivirine, elvitegravir and dolutegravir in mouse biological matrices by LC-MS/MS and its application to a pharmacokinetic study

Combination antiretroviral (cARV) treatment is more common in human immunodeficiency virus (HIV) infection. In many instances, treatment regimen includes two or more combination of drugs from six different classes. Some of the antiretroviral combination medications are under study at preclinical and clinical stages. A precise method is required to quantify the drug concentration in biological matrices to study pharmacokinetic behavior and tissue distribution profile in animals and/or humans. We have developed and validated a sensitive and precise liquid chromatography-tandem mass spectrometry method for simultaneous quantification of selected antiretroviral drugs, tenofovir (TNF), emtricitabine (FTC), rilpivirine (RPV), dolutegravir (DTG) and elvitegravir (EVG) in mouse biological matrices. This method involves a solid phase extraction, simple isocratic chromatographic separation using Restek Pinnacle DB BiPh column (50mm×2.1mm, 5μm) and mass spectrometric detection by an API 3200 Q Trap instrument. The total run time for each sample was 6min. The method was validated in the concentration range of 5-2000ng/mL for FTC, RPV, DTG, EVG and 10-4000ng/mL for TNF respectively with correlation coefficients (r(2)) higher than 0.9976. The results of intra and inter-run assay precision and accuracy were within acceptance limits for all the five analytes. This method was used to support the study of pharmacokinetics and tissue distribution profile of nanoformulated antiretroviral drugs in mice.

A Cross-Sectional Survey of HIV Testing and Prevalence in Twelve Brazilian Correctional Facilities

BACKGROUND

Prior studies have reported higher HIV prevalence among prisoners than the general population in Brazil, but data have been derived from single prisons. The aim of this study was to evaluate HIV testing practices, prevalence and linkage to care among inmates in a network of 12 prisons.

METHODS

We administered a questionnaire to a population-based sample of inmates from 12 prisons in Central-West Brazil and collected sera for HIV and syphilis testing from January to December 2013. We evaluated factors associated with HIV testing and infection using multivariable logistic regression models. Six months after HIV testing, we assessed whether each HIV-infected prisoner was engaged in clinical care and whether they had started antiretroviral therapy.

RESULTS

We recruited 3,362 inmates, of whom 2,843 (85%) were men from 8 prisons, and 519 (15%) were women from 4 prisons. Forty-five percent of participants reported never having been tested for HIV previously. In multivariable analysis, the variables associated with previous HIV testing were lack of a stable partner (adjusted odds ratio [AOR]: 1.38; 95% CI: 1.18-1.60), completed more than four years of schooling (AOR 1.40; 95% CI: 1.20-1.64), history of previous incarceration (AOR: 1.68; 95% CI: 1.43-1.98), history of mental illness (AOR 1.52; 95% CI: 1.31-1.78) and previous surgery (AOR 1.31; 95% CI: 1.12-1.52). Fifty-four (1.6%) of all participants tested positive for HIV; this included 44 (1.54%) men and 10 (1.92%) women. Among male inmates, HIV infection was associated with homosexuality (AOR 6.20, 95% CI: 1.73-22.22), self-report of mental illness (AOR 2.18, 95% CI: 1.13-4.18), history of sexually transmitted infections (AOR 3.28, 95% CI: 1.64-6.56), and syphilis sero-positivity (AOR 2.54, 95% CI: 1.20-5.39). Among HIV-infected individuals, 34 (63%) were unaware of their HIV status; only 23 of these 34 (68%) newly diagnosed participants could be reached at six month follow-up, and 21 of 23 (91%) were engaged in HIV care.

CONCLUSIONS

HIV testing rates among prison inmates are low, and the majority of HIV-infected inmates were unaware of their HIV diagnosis. Incarceration can be an opportunity for diagnosis and treatment of HIV among vulnerable populations who have poor access to health services, but further work is needed on transitional HIV care for released inmates.

Anti-Retroviral Lectins Have Modest Effects on Adherence of Trichomonas vaginalis to Epithelial Cells In Vitro and on Recovery of Tritrichomonas foetus in a Mouse Vaginal Model

Trichomonas vaginalis causes vaginitis and increases the risk of HIV transmission by heterosexual sex, while Tritrichomonas foetus causes premature abortion in cattle. Our goals were to determine the effects, if any, of anti-retroviral lectins, which are designed to prevent heterosexual transmission of HIV, on adherence of Trichomonas to ectocervical cells and on Tritrichomonas infections in a mouse model. We show that Trichomonas Asn-linked glycans (N-glycans), like those of HIV, bind the mannose-binding lectin (MBL) that is part of the innate immune system. N-glycans of Trichomonas and Tritrichomonas bind anti-retroviral lectins (cyanovirin-N and griffithsin) and the 2G12 monoclonal antibody, each of which binds HIV N-glycans. Binding of cyanovirin-N appears to be independent of susceptibility to metronidazole, the major drug used to treat Trichomonas. Anti-retroviral lectins, MBL, and galectin-1 cause Trichomonas to self-aggregate and precipitate. The anti-retroviral lectins also increase adherence of ricin-resistant mutants, which are less adherent than parent cells, to ectocervical cell monolayers and to organotypic EpiVaginal tissue cells. Topical application of either anti-retroviral lectins or yeast N-glycans decreases by 40 to 70% the recovery of Tritrichomonas from the mouse vagina. These results, which are explained by a few simple models, suggest that the anti-retroviral lectins have a modest potential for preventing or treating human infections with Trichomonas.

Mapping antiretroviral drugs in tissue by IR-MALDESI MSI coupled to the Q Exactive and comparison with LC-MS/MS SRM assay

This work describes the coupling of the IR-MALDESI imaging source with the Q Exactive mass spectrometer. IR-MALDESI MSI was used to elucidate the spatial distribution of several HIV drugs in cervical tissues that had been incubated in either a low or high concentration. Serial sections of those analyzed by IR-MALDESI MSI were homogenized and analyzed by LC-MS/MS to quantify the amount of each drug present in the tissue. By comparing the two techniques, an agreement between the average intensities from the imaging experiment and the absolute quantities for each drug was observed. This correlation between these two techniques serves as a prerequisite to quantitative IR-MALDESI MSI. In addition, a targeted MS(2) imaging experiment was also conducted to demonstrate the capabilities of the Q Exactive and to highlight the added selectivity that can be obtained with SRM or MRM imaging experiments.

Structural basis of Mos1 transposase inhibition by the anti-retroviral drug Raltegravir

DNA transposases catalyze the movement of transposons around genomes by a cut-and-paste mechanism related to retroviral integration. Transposases and retroviral integrases share a common RNaseH-like domain with a catalytic DDE/D triad that coordinates the divalent cations required for DNA cleavage and integration. The anti-retroviral drugs Raltegravir and Elvitegravir inhibit integrases by displacing viral DNA ends from the catalytic metal ions. We demonstrate that Raltegravir, but not Elvitegravir, binds to Mos1 transposase in the presence of Mg(2+) or Mn(2+), without the requirement for transposon DNA, and inhibits transposon cleavage and DNA integration in biochemical assays. Crystal structures at 1.7 Å resolution show Raltegravir, in common with integrases, coordinating two Mg(2+) or Mn(2+) ions in the Mos1 active site. However, in the absence of transposon ends, the drug adopts an unusual, compact binding mode distinct from that observed in the active site of the prototype foamy virus integrase.

The role of lopinavir/ritonavir (Kaletra®) in the management of HIV infected adults

As the HIV pandemic enters its third decade, more sophisticated and efficacious therapies are continually being developed. This article provides an in-depth review of the first coformulated boosted protease inhibitor available on the world market, lopinavir/ritonavir (Kaletra). Included in this review is an overview of the current market place, the chemistry, pharmacokinetics, clinical efficacy and side-effect profile of lopinavir/ritonavir. In addition, an expert opinion and commentary on the clinical applications of this drug is provided.

Towards an improved anti-HIV activity of NRTI via metal-organic frameworks nanoparticles

Nanoscale mesoporous iron carboxylates metal-organic frameworks (nanoMOFs) have recently emerged as promising platforms for drug delivery, showing biodegradability, biocompatibility and important loading capability of challenging highly water-soluble drugs such as azidothymidine tryphosphate (AZT-TP). In this study, nanoMOFs made of iron trimesate (MIL-100) were able to act as efficient molecular sponges, quickly adsorbing up to 24 wt% AZT-TP with entrapment efficiencies close to 100%, without perturbation of the supramolecular crystalline organization. These data are in agreement with molecular modelling predictions, indicating maximal loadings of 33 wt% and preferential location of the drug in the large cages. Spectrophotometry, isothermal titration calorimetry, and solid state NMR investigations enable to gain insight on the mechanism of interaction of AZT and AZT-TP with the nanoMOFs, pointing out the crucial role of phosphates strongly coordinating with the unsaturated iron(III) sites. Finally, contrarily to the free AZT-TP, the loaded nanoparticles efficiently penetrate and release their cargo of active triphosphorylated AZT inside major HIV target cells, efficiently protecting against HIV infection.

A validated assay by liquid chromatography-tandem mass spectrometry for the simultaneous quantification of elvitegravir and rilpivirine in HIV positive patients

Because of the large variability in the pharmacokinetics of anti-HIV drugs, therapeutic drug monitoring in patients may contribute to optimize the overall efficacy and safety of antiretroviral therapy. An LC-MS/MS method for the simultaneous assay in plasma of the novel antiretroviral agents rilpivirine (RPV) and elvitegravir (EVG) has been developed to that endeavor. Plasma samples (100 μL) extraction is performed by protein precipitation with acetonitrile, and the supernatant is subsequently diluted 1:1 with 20-mM ammonium acetate/MeOH 50:50. After reverse-phase chromatography, quantification of RPV and EVG, using matrix-matched calibration samples, is performed by electrospray ionization-triple quadrupole mass spectrometry by selected reaction monitoring detection using the positive mode. The stable isotopic-labeled compounds RPV-(13) C6 and EVG-D6 were used as internal standards. The method was validated according to FDA recommendations, including assessment of extraction yield, matrix effects variability (<6.4%), as well as EVG and RPV short and long-term stability in plasma. Calibration curves were validated over the clinically relevant concentrations ranging from 5 to 2500 ng/ml for RPV and from 50 to 5000 ng/ml for EVG. The method is precise (inter-day CV%: 3-6.3%) and accurate (3.8-7.2%). Plasma samples were found to be stable (<15%) in all considered conditions (RT/48 h, +4°C/48 h, -20°C/3 months and 60°C/1 h). Selected metabolite profiles analysis in patients' samples revealed the presence of EVG glucuronide, that was well separated from parent EVG, allowing to exclude potential interferences through the in-source dissociation of glucuronide to parent drug. This new, rapid and robust LCMS/MS assay for the simultaneous quantification of plasma concentrations of these two major new anti-HIV drugs EVG and RPV offers an efficient analytical tool for clinical pharmacokinetics studies and routine therapeutic drug monitoring service.

Charge-surrounded pockets and electrostatic interactions with small ions modulate the activity of retroviral fusion proteins

Refolding of viral class-1 membrane fusion proteins from a native state to a trimer-of-hairpins structure promotes entry of viruses into cells. Here we present the structure of the bovine leukaemia virus transmembrane glycoprotein (TM) and identify a group of asparagine residues at the membrane-distal end of the trimer-of-hairpins that is strikingly conserved among divergent viruses. These asparagines are not essential for surface display of pre-fusogenic envelope. Instead, substitution of these residues dramatically disrupts membrane fusion. Our data indicate that, through electrostatic interactions with a chloride ion, the asparagine residues promote assembly and profoundly stabilize the fusion-active structures that are required for viral envelope-mediated membrane fusion. Moreover, the BLV TM structure also reveals a charge-surrounded hydrophobic pocket on the central coiled coil and interactions with basic residues that cluster around this pocket are critical to membrane fusion and form a target for peptide inhibitors of envelope function. Charge-surrounded pockets and electrostatic interactions with small ions are common among class-1 fusion proteins, suggesting that small molecules that specifically target such motifs should prevent assembly of the trimer-of-hairpins and be of value as therapeutic inhibitors of viral entry.

Human T-cell leukaemia virus types-1 (HTLV-1) and bovine leukaemia virus (BLV) are divergent blood borne viruses that cause hematological malignancies in humans and cattle respectively. In common with other enveloped viruses, infection of cells by HTLV-1 and BLV is dependent on the membrane fusion properties of the viral envelope glycoproteins. Here we have solved the crystal structure of the BLV transmembrane glycoprotein, and, through a functional and comparative analysis with HTLV-1, we have identified features that are critical to fusion protein function. In particular, we demonstrate that electrostatic interactions with small ions dramatically stabilize the assembly and fusion-associated forms of the BLV TM, but are not required for the cell surface display of native pre-fusogenic envelope. Moreover, we show that charged residues that border a deep hydrophobic pocket contribute directly to appropriate folding of fusion-active envelope and are critical to membrane fusion. Importantly, the charged residues that border the pocket are key features that determine the specificity and activity of peptide inhibitors of envelope function. Our study demonstrates that charge-surrounded pockets and electrostatic interactions with small ions are significant leitmotifs of diverse class-1 fusion proteins and that these elements represent ideal targets for novel small-molecule inhibitors of viral entry.

Fate of the antiretroviral drug tenofovir in agricultural soil

Tenofovir (9-(R)-(2-phosphonylmethoxypropyl)-adenine) is an antiretroviral drug widely used for the treatment of human immunodeficiency virus (HIV-1) and Hepatitis B virus (HBV) infections. Tenofovir is extensively and rapidly excreted unchanged in the urine. In the expectation that tenofovir could potentially reach agricultural lands through the application of municipal biosolids or wastewater, and in the absence of any environmental fate data, we evaluated its persistence in selected agricultural soils. Less than 10% of [adenine-8-(14)C]-tenofovir added to soils varying widely in texture (sand, loam, clay loam) was mineralized in a 2-month incubation under laboratory conditions. Tenofovir was less readily extractable from clay soils than from a loam or a sandy loam soil. Radioactive residues of tenofovir were removed from the soil extractable fraction with DT(50)s ranging from 24±2 to 67+22days (first order kinetic model) or 44+9 to 127+55days (zero order model). No extractable transformation products were detectable by HPLC. Tenofovir mineralization in the loam soil increased with temperature (range 4°C to 30°C), and did not occur in autoclaved soil, suggesting a microbial basis. Mineralization rates increased with soil moisture content, ranging from air-dried to saturated. In summary, tenofovir was relatively persistent in soils, there were no extractable transformation products detected, and the response of [adenine-8-(14)C]-tenofovir mineralization to soil temperature and heat sterilization indicated that the molecule was biodegraded by aerobic microorganisms. Sorption isotherms with dewatered biosolids suggested that tenofovir residues could potentially partition into the particulate fraction during sewage treatment.

Adaptive evolution of Mus Apobec3 includes retroviral insertion and positive selection at two clusters of residues flanking the substrate groove

Mouse APOBEC3 (mA3) is a cytidine deaminase with antiviral activity. mA3 is linked to the Rfv3 virus resistance factor, a gene responsible for recovery from infection by Friend murine leukemia virus, and mA3 allelic variants differ in their ability to restrict mouse mammary tumor virus. We sequenced mA3 genes from 38 inbred strains and wild mouse species, and compared the mouse sequence and predicted structure with human APOBEC3G (hA3G). An inserted sequence was identified in the virus restrictive C57BL strain allele that disrupts a splice donor site. This insertion represents the long terminal repeat of the xenotropic mouse gammaretrovirus, and was acquired in Eurasian mice that harbor xenotropic retrovirus. This viral regulatory sequence does not alter splicing but is associated with elevated mA3 expression levels in spleens of laboratory and wild-derived mice. Analysis of Mus mA3 coding sequences produced evidence of positive selection and identified 10 codons with very high posterior probabilities of having evolved under positive selection. Six of these codons lie in two clusters in the N-terminal catalytically active cytidine deaminase domain (CDA), and 5 of those 6 codons are polymorphic in Rfv3 virus restrictive and nonrestrictive mice and align with hA3G CDA codons that are critical for deaminase activity. Homology models of mA3 indicate that the two selected codon clusters specify residues that are opposite each other along the predicted CDA active site groove, and that one cluster corresponds to an hAPOBEC substrate recognition loop. Substitutions at these clustered mA3 codons alter antiviral activity. This analysis suggests that mA3 has been under positive selection throughout Mus evolution, and identified an inserted retroviral regulatory sequence associated with enhanced expression in virus resistant mice and specific residues that modulate antiviral activity.

APOBEC3 (mA3) is a cytidine deaminase with antiretroviral activity. Genetic variants of mA3 are associated with the restriction factor Rfv3 (recovery from Friend leukemia virus) and with resistance to mouse mammary tumor virus. We sequenced mA3 from laboratory strains and wild mouse species to examine its evolution. We discovered that the mA3 allele in virus resistant mice is disrupted by insertion of the regulatory sequences of a mouse leukemia virus, and this insertion is associated with enhanced mA3 expression. We also subjected the Mus mA3 protein coding sequences to statistical analysis to determine if specific sites are subject to strong positive selection, that is, show an increased number of amino acid replacement mutations. We identified 10 such sites, most of which distinguish the mA3 genes of Rfv3 virus restrictive and nonrestrictive mice. Six of these sites are in two clusters that, in human APOBEC3G, are important for function. We generated a structural model of mA3, positioned these clusters opposite each other along the putative mA3 active site groove, and demonstrated that substitutions at these sites alter antiviral activity. Thus, mA3 has been involved in genetic conflicts throughout mouse evolution, and we identify an inserted regulatory sequence and two codon clusters that contribute to mA3 antiviral function.

Segmented polyurethane intravaginal rings for the sustained combined delivery of antiretroviral agents dapivirine and tenofovir

Dual segment polyurethane intravaginal rings (IVRs) were fabricated to enable sustained release of antiretroviral agents dapivirine and tenofovir to prevent the male to female sexual transmission of the human immunodeficiency virus. Due to the contrasting hydrophilicity of the two drugs, dapivirine and tenofovir were separately formulated into polymers with matching hydrophilicity via solvent casting and hot melt extrusion. The resultant drug loaded rods were then joined together to form dual segment IVRs. Compression testing of the IVRs revealed that they are mechanically comparable to the widely accepted NuvaRing IVR. Physical characterization of the individual IVR segments using wide angle X-ray scattering and differential scanning calorimetry determined that dapivirine and tenofovir are amorphous and crystalline within their polymeric segments, respectively. In vitro release of tenofovir from the dual segment IVR was sustained over 30 days while dapivirine exhibited linear release over the time period. A 90 day accelerated stability study confirmed that dapivirine and tenofovir are stable in the IVR formulation. Altogether, these results suggest that multisegment polyurethane IVRs are an attractive formulation for the sustained vaginal delivery of drugs with contrasting hydrophilicity such as dapivirine and tenofovir.

Novel tight binding PETT, HEPT and DABO-based non-nucleoside inhibitors of HIV-1 reverse transcriptase

Non-nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) are a key component of effective combination antiretroviral therapies for HIV/AIDS. NNRTIs despite their chemical diversity, bind to a common allosteric site of HIV-1 RT, the primary target for anti-AIDS chemotherapy, and noncompetitively inhibit DNA polymerization. NNRTIs currently in clinical use have a low genetic barrier to resistance and therefore, the need for novel NNRTIs active against drug-resistant mutants selected by current therapies is of paramount importance. We describe the chemistry and biological evaluation of highly potent novel phenethylthiazolylthiourea (PETT), 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) and dihydroalkoxybenzyloxopyrimidine (DABO) derivatives targeting the hydrophobic binding pocket of HIV-1 RT. These NNRTIs were rationally designed by molecular modeling and docking studies using a novel composite binding pocket that predicted how drug-resistant mutations would change the RT binding pocket shape, volume, and chemical make-up and how these changes could affect NNRTI binding. Several ligand derivatization sites were identified for docked NNRTIs that fit the composite binding pocket. The best fit was determined by calculating an inhibition constant (Ludi Ki) of the docked compound for the composite binding pocket. Compounds with a Ludi Ki of <1 microM were identified as the most promising tight binding NNRTIs. These NNRTIs displayed high selective indices with robust anti-HIV-1 activity against the wild-type and drug-resistant isolates carrying multiple RT gene mutations. The high rate of treatment failure due to the emergence of drug resistance mutations makes the discovery of broad-spectrum PETT, HEPT and DABO-based NNRTIs useful as a component of effective combination regimens.

HIV-1 Integrase: From Biology to Chemotherapeutics

AIDS has claimed the lives of 25 million people worldwide, an additional 40 million people are HIV-infected and new cases are being diagnosed every year. Despite the fact that HAART has moved AIDS from the category of terminal diseases to that of treatable chronic illnesses, its long-term therapeutic success may be compromised by the development of resistance to the currently used drugs. Despite the availability of RT, PR and fusion inhibitors, the development of further drugs such as inhibitors that target the third enzyme IN is essential for the clinical management of HIV-infected patients. The absence of cellular homolgues to IN and the unique nature of the reactions catalyzed by IN, make it an ideal target for drug design. Considerable progress towards designing HIV-1 IN inhibitors has been made over the last years and several lead compounds have been identified, synthesized and clinically studied. This review focuses on the existing knowledge of the biology of HIV-1 IN with emphasis on the mechanism of integration, structure and function and the technologies for measuring IN activity. This is followed by the current trends on designing HIV-1 IN inhibitors with the aid of molecular informatics and a review on the main classes of HIV-1 IN inhibitors reported this far with special emphasis on the clinical candidates.

Phosphonated Carbocyclic 2‘-Oxa-3‘-azanucleosides as New Antiretroviral Agents

Phosphonated carbocyclic 2'-oxa-3'-azanucleosides have been synthesized and tested for their antiretroviral activity. The obtained results have shown that some of the compounds were as powerful as azydothymidine in inhibiting the reverse transcriptase activity of the human retrovirus T-cell leukemia/lymphotropic virus type 1 and in protecting human peripheral blood mononuclear cells against human retrovirus T-cell leukemia/lymphotropic virus type 1 transmission in vitro. These data indicate that phosphonated carbocyclic 2'-oxa-3'-azanucleosides possess the necessary requirements to efficiently counteract infections caused by human retroviruses.

Modifications of aminoglycoside antibiotics targeting RNA

The increased awareness of the central role of RNA has led to realization that RNA, as structural and functional information accumulation, is also drug target to small molecular therapy. Aminoglycosides are a group of well-known antibiotics, which function through binding to specific sites in prokaryotic ribosomal RNA (rRNA) and affecting the fidelity of protein synthesis. Unfortunately, their clinical practice has been curtailed by toxicity and rapid increasing number of resistant strains. Therefore, it is highly desirable to design new modified aminoglycosides that will overcome the undesirable properties of natural occurring aminoglycosides. On the other hand, aminoglycosides as potential antiviral (HIV) agents were also reported. Herein, we survey the current efforts to develop new aminoglycoside derivatives with modification and reconstruction on each sugar ring and review the latest advances in structure-activity relationships (SAR).

The intrinsic antiretroviral factor APOBEC3B contains two enzymatically active cytidine deaminase domains

The mammalian APOBEC3 proteins are cytidine deaminases that function as inhibitors of retrovirus replication and retrotransposon mobility. An issue that has remained controversial is whether the editing of deoxycytidine residues to deoxyuridine is necessary and sufficient for this inhibition or whether APOBEC3 proteins also exert a second, distinct inhibitory mechanism. Here, we present an analysis of the ability of mutants of APOBEC3G and APOBEC3B, both of which contain two consensus cytidine deaminase active sites, to inhibit the replication of human immunodeficiency virus. Our data confirm that APOBEC3G only contains a single, carboxy-terminal active site but, surprisingly, reveal that both cytidine deaminase consensus sequences in APOBEC3B are enzymatically active. Enzymatically inactive mutant forms of APOBEC3G and APOBEC3B were found to retain the ability to inhibit the infectivity of HIV-1 virions produced in their presence by approximately 4-fold and approximately 8-fold, respectively. While this inhibition was significantly less than the level seen with wild-type forms of A3G or A3B, these data, nevertheless argue that the inhibition of HIV-1 by APOBEC3 proteins is at least partly independent of DNA editing.

Electrospray tandem mass spectroscopic characterisation of 18 antiretroviral drugs and simultaneous quantification of 12 antiretrovirals in plasma

The determination of antiretroviral drug concentrations in patients treated with highly active antiretroviral therapy (HAART) is an essential part of optimum patient management because of the multitude of pharmacokinetic drug interactions between these drugs and the risk of treatment failure or viral resistance if therapeutic concentrations are not reached. Currently, 21 different antiretrovirals are used in various combinations rendering therapeutic drug monitoring a laborious task. We therefore aimed to simultaneously determine as many antiretrovirals as possible using triple quadrupole mass spectroscopy with electrospray ionisation. For this purpose, spectra and fragmentation patterns of the protease inhibitors amprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir, the non-nucleoside reverse transcriptase inhibitors delavirdine, efavirenz, and nevirapine, the nucleoside reverse transcription inhibitors abacavir, didanosine, emtricitabine, lamivudine, stavudine, zalcitabine, and zidovudine, and the nucleotide reverse transcriptase inhibitor tenofovir were evaluated. A bioanalytical method to determine all protease and non-nucleoside reverse transcriptase inhibitors, and zalcitabine and zidovudine concentrations in biological matrices was developed. Samples were prepared by protein precipitation with methanol after addition of three different internal standards. Antiretrovirals were separated by high-performance liquid chromatography on a Nucleosil C18-100 Nautilus column using a gradient of 20 mM ammonium acetate including 0.1% aqueous acetic acid and acetonitrile and detected by electrospray ionisation/tandem mass spectrometry in the negative (efavirenz, stavudine, zidovudine) or positive ionisation mode (all other compounds). The bioanalytical method was successfully validated according to FDA guidelines and applied to plasma and cerebrospinal fluid samples of patients treated for acquired immunodeficiency syndrome (AIDS).

Simultaneous determination of 17 antiretroviral drugs in human plasma for quantitative analysis with liquid chromatography–tandem mass spectrometry

This work describes a sensitive method for the simultaneous determination of 17 antiretroviral drugs including nucleoside analog reverse transcriptase inhibitors, non-nucleoside analog reverse transcriptase inhibitors, protease inhibitors and a nucleotide analog reverse transcriptase inhibitor in 50 microL of human plasma. This method employed high-performance liquid chromatography-tandem mass spectrometry with electrospray ionization. The analytes were monitored in multiple reaction monitoring mode and the polarity was switched from positive to negative to positive to detect all compounds after a single injection. A combination of liquid-liquid extraction and protein precipitation was used to extract all compounds, with at least 75% recovery for all analytes. Within- and between-day accuracies were at least 85% for 1-500 ng/mL for nelfinavir, indinavir and abacavir, 10-500 ng/mL for didanosine and stavudine and 5-500 ng/mL for all other compounds. This method is very effective for quantifying and screening antiretroviral drugs in clinical samples with limited (50 microL) volumes.

Template properties of mutagenic cytosine analogues in reverse transcription

We have studied the mutagenic properties of ribonucleotide analogues by reverse transcription to understand their potential as antiretroviral agents by mutagenesis of the viral genome. The templating properties of nucleotide analogues including 6-(β-D-ribofuranosyl)-3,4-dihydro-8H-pyrimido[4,5-c](1,2)oxazin-7-one, N⁴-hydroxycytidine, N⁴-methoxycytidine, N⁴-methylcytidine and 4-semicarbazidocytidine, which have been reported to exhibit ambiguous base pairing properties, were examined. We have synthesized RNA templates using T3 RNA polymerase, and investigated the specificity of the incorporation of deoxyribonucleoside triphosphates opposite these cytidine analogues in RNA by HIV and AMV reverse transcriptases. Except for N⁴-methylcytidine, both enzymes incorporated both dAMP and dGMP opposite these analogues in RNA. This indicates that they would be highly mutagenic if present in viral RNA. To study the basis of the differences among the analogues in the incorporation ratios of dAMP to dGMP, we have carried out kinetic analysis of incorporation opposite the analogues at a defined position in RNA templates. In addition, we examined whether the triphosphates of these analogues were incorporated competitively into RNA by human RNA polymerase II. Our present data supports the view that these cytidine analogues are mutagenic when incorporated into RNA, and that they may therefore be considered as candidates for antiviral agents by causing mutations to the retroviral genome.

Role of nanotechnology in HIV/AIDS treatment: potential to overcome the viral reservoir challenge

Insufficient concentrations and very short residence time of the anti-retroviral agents at the cellular and anatomical sites are among major factors that contribute to the failure of eradicating HIV from reservoirs and the development of multidrug resistance against antiretroviral agents. In recent years, nanotechnology-based drug delivery systems have shown remarkable ability to overcome many of the same anatomical and physiological barriers and deliver the therapeutic agents locally at the site of systemic diseases such as cancer.

3'-azido-3'-deoxy-5'-O-isonicotinoylthymidine: a novel antiretroviral analog of zidovudine. III. Solubility studies

The pH-solubility behavior and solubility of 3'-azido-3'-deoxy-5'-O-isonicotinoylthymidine (AZT-Iso), an antiretroviral derivative of zidovudine with important biological activity, was studied in water, ethanol, ethanol: water, and n-octanol. The N-pyridine pKa value was determined from its pH-solubility profile, which was in accordance with that of the experimental value of methyl isonicotinate. Also, the ethanol cosolvency in ethanol:water mixtures at 25 degrees C was studied, and log-linear and nonlinear solubilization models were applied to the experimental solubility AZT-Iso data, which allowed us to predict its solubility in those solvent mixtures at a determined content of cosolvent.

In vitro and in vivo anti-retroviral activity of the substance purified from the aqueous extract of Chelidonium majus L

We have isolated a substance with anti-retroviral activity from the freshly prepared crude extract of Chelidonium majus L. (greater celandine) by 9-aminoacridine precipitation method and ion exchange chromatography using Dowex-50W/H+ resin followed by the gel filtration on Sephadex-75 column. Elemental and phenol/sulfuric acid method analyses as well as the mass spectrometry of the purified substance indicated that it may represent a low-sulfated poly-glycosaminoglycan moiety with molecular weight of approximately 3800 Da. The substance prevented infection of human CD4+ T-cell lines AA2 and H9 with HIV-1 at concentration of 25 microg/mL as well as the cell-to-cell virus spread in H9 cells continuously infected with HIV-1, as determined by the measurement of reverse transcriptase activity and p24 content in cell cultures. Furthermore, we have shown in a murine AIDS model that the treatment with purified substance significantly prevented splenomegaly and the enlargement of cervical lymph nodes in C57Bl/6 mice chronically infected with the pool of murine leukemia retroviruses. The mechanism(s) of anti-retroviral activity of this substance have to be elucidated.

An in vitro study of the design and development of a novel doughnut-shaped minitablet for intraocular implantation

A novel doughnut-shaped minitablet (DSMT) was developed and evaluated as a biodegradable intraocular drug delivery system for rate-modulated delivery of antiviral bioactives. The DSMT device was manufactured using a special set of punches fitted with a central-rod in a Manesty tableting press. The DSMT device released the antiretrovirals foscarnet and ganciclovir at a first-order rate. The erosion kinetics was assessed by gravimetric analysis and scanning electron microscopy. The device gradually eroded when immersed in simulated vitreous humor (SVH) (pH 7.4, 37 degrees C) and released bioactives in a sustained manner. The novel geometric design and veracity of the DSMT device was retained even after 24 weeks of erosion. When considering the duration of the bioactive released from the DSMT device, it was found that by the careful selection of the type and concentration of polymer employed in formulating the DSMT device, it was possible to produce a device that could release drug for any period up to 12 months.

HIV-1 integrase inhibitors: 2003–2004 update

The integration of viral cDNA into the host genome is an essential step in the HIV-1-life cycle and is mediated by the virally encoded enzyme, integrase (IN). Inhibition of this process provides an attractive strategy for antiviral drug design. The discovery of beta-diketo acid inhibitors played a major role in validating IN as a legitimate antiretroviral drug target. Over a decade of research, a plethora of IN inhibitors have been discovered and some showed antiviral activity consistent with their effect on IN. To date, at least two compounds have been tested in human but none are close to the FDA approval. In this review, we provide a comprehensive report of all small-molecule IN inhibitors discovered during the years 2003 and 2004. Compilation of such data will prove beneficial in developing QSAR, virtual screening, pharmacophore hypothesis generation, and validation.

Stronger anti-HIV-1 activity of C-peptide derived from HIV-1 89.6 gp41 C-terminal heptad repeated sequence

C34-LAI containing amino acids 118 to 151 of the HIV-1(LAI) gp41 ectodomain exhibits potent anti-HIV-1 activity. However, the N-terminal halves of C34 peptides vary more according to the HIV-1 strain than the C-terminal halves. Therefore, an analysis was conducted on the anti-HIV-1 activities of the C34 peptides derived from various HIV-1 strains. C34-89.6 exhibited the strongest anti-HIV-1 activity among the C34 peptides tested. Interestingly, its N-terminal half was more acidic than those of the other C34 peptides, whereas its C-terminal half was more basic. Since the C-peptides derived from the HIV-1(LAI) strain are used extensively, the anti-HIV-1 activities of these peptides were compared between the HIV-1 strains 89.6 and LAI. When using chimeric peptides, it was found that the C-terminal basic region of C34-89.6 was more critical than its N-terminal basic region. The anti-HIV-1 activity of T20-89.6 and C28-89.6 was also stronger than that of T20-LAI and C28-LAI, respectively. The anti-HIV-1 activity of C28-89.6 was weakened when the C-terminal basic residues were changed to the corresponding residues of C28-LAI. However, no conformational differences were found among the C28 peptides. Accordingly, these results imply that introducing the C-terminal basic residues of the HIV-1 89.6 C-peptide may be useful for developing potent anti-HIV-1 drugs.

Determination of antiretroviral agents in human serum by capillary electrophoresis

In this work, a simple and rapid electrokinetic chromatography method for the simultaneous separation of different protease inhibitors (indinavir, ritonavir, saquinavir, nelfinavir), nucleoside reverse transcriptase inhibitors (stavudine, zidovudine, didanosine) and non-nucleoside reverse transcriptase inhibitors (nevirapine, efavirenz) was developed. The analyses were performed in a 75 microm i.d. uncoated fused-silica capillary with 48.5 cm length (effective length of 40 cm) using a running buffer consisting of 20 mmol L(-1) sodium dodecyl sulfate, 10 mmol L(-1) sodium tetraborate, 30% acetonitrile and 5% ethanol. Samples were injected hydrodynamically by applying 50 mbar pressure during 6 s. All analytes were separated within 10 min with a voltage of 20 kV. The proposed method was validated for zidovudine, didanosine and efavirenz in human serum. Serum samples were prepared using a solid-phase extraction procedure (Waters Oasis HLB cartridges). For quantitative purposes, stavudine was chosen as the internal standard (IS). Method validation parameters were determined revealing good migration time repeatability (<0.7% RSD) and peak area repeatability (<1.2% RSD). Intra- and inter-day precisions were less than 1.7% and 4.4% RSD, respectively. Matrix matching analytical curves for each drug were linear in the 1.0-20.0 microg mL(-1) interval (r > 0.998). Limits of detection (LOD) were in range of 0.3-0.5 microg mL(-1). The extraction recoveries were higher than 90% with exception of efavirenz, which was 77.4%. Based on the performance characteristics, the proposed method was found suitable for the determination of zidovudine, didanosine and efavirenz in serum samples.

Rhinovirus-stabilizing activity of artificial VLDL-receptor variants defines a new mechanism for virus neutralization by soluble receptors

Members of the low-density lipoprotein receptor family possess various numbers of ligand binding repeats that non-equally contribute to binding of minor group human rhinoviruses. Using an artificial concatemer of five copies of repeat 3 of the human very-low density lipoprotein receptor, we demonstrate protection of HRV2 against low-pH mediated uncoating and inhibition of penetration of an RNA-specific fluorescent dye into the intact virion. This indicates that the recombinant receptor inhibits viral breathing and irreversible conformational modifications of the capsid that precede RNA release, providing a new mechanism for rhinovirus neutralization by soluble receptor molecules.

Mutational comparison of the single-domained APOBEC3C and double-domained APOBEC3F/G anti-retroviral cytidine deaminases provides insight into their DNA target site specificities

Human APOBEC3F and APOBEC3G are double-domained deaminases that can catalyze dC→dU deamination in HIV-1 and MLV retroviral DNA replication intermediates, targeting T–C or C–C dinucleotides, respectively. HIV-1 antagonizes their action through its vif gene product, which has been shown (at least in the case of APOBEC3G) to interact with the N-terminal domain of the deaminase, triggering its degradation. Here, we compare APOBEC3F and APOBEC3G to APOBEC3C, a single-domained deaminase that can also act on both HIV-1 and MLV. We find that whereas APOBEC3C contains all the information necessary for both Vif-binding and cytidine deaminase activity in a single domain, it is the C-terminal domain of APOBEC3F and APOBEC3G that confer their target site specificity for cytidine deamination. We have exploited the fact that APOBEC3C, whilst highly homologous to the C-terminal domain of APOBEC3F, exhibits a distinct target site specificity (preferring Y–C dinucleotides) in order to identify residues in APOBEC3F that might affect its target site specificity. We find that this specificity can be altered by single amino acid substitutions at several distinct positions, suggesting that the strong dependence of APOBEC3-mediated deoxycytidine deamination on the 5′-flanking nucleotide is sensitive to relatively subtle changes in the APOBEC3 structure. The approach has allowed the isolation of APOBEC3 DNA mutators that exhibit novel target site preferences.

Antiretroviral Drug Content in Products from Developing Countries

Generic and brand name antiretroviral drugs are becoming increasingly available in developing countries. We analyzed 6 antiretroviral medications from 4 international sources for drug content. The active ingredient in tested drug products was within 15% of the labeled amount (range, -12% to +15%) for drugs that were properly stored.

Conformational studies of novel antiretroviral analogs of zidovudine

Conformational properties of three novel zidovudine analogs, namely 3'-azido-3'-deoxy-5'-O-isonicotinoylthymidine (AZT-Iso, 2), (-)-trans-(5S,6S)-5-bromo-6, 5'-epoxy-5,6-dihydro-3'-azido-3'-deoxythymidine (3) and (+)-trans-(5R,6R)-5-bromo-6,5'-epoxy-5,6-dihydro-3'-azido-3'-deoxythymidine (4), have been investigated by AM1 calculations and NMR studies, and compared with those of the parent nucleoside (AZT, 1). Based on the results obtained the following correlation may be established, a) AZT and AZT-Iso exhibit a conformational behavior analog to other pyrimidinic nucleosides, displaying a dynamic equilibrium in solution where the two conformers (North and South) undergo a constant transformation. b) Compounds 3 and 4 show a different conformational profile. The estimate of the pseudorotation phase angle reveals the rigid structures of the latter compounds, which do not evidence conformational equilibrium in solution; the azide group being the only group free to rotate. c) Diastereoisomers 3 and 4 exhibit an extra conformational parameter compared with other pyrimidinic nucleosides: the chair or boat conformation in the third ring formed between the sugar and the base. In all cases, a reasonable correlation was obtained between theoretical and NMR spectroscopic data.