Inhibition Of Human Immunodeficiency Virus Research Articles

Targeting Dynamic Pockets of HIV-1 Protease by Structure-Based Computational Screening for Allosteric Inhibitors

We present the discovery of low molecular weight inhibitors of human immunodeficiency virus 1 (HIV-1) protease subtype B that were identified by structure-based virtual screening as ligands of an allosteric surface cavity. For pocket identification and prioritization, we performed a molecular dynamics simulation and observed several flexible, partially transient surface cavities. For one of these presumable ligand-binding pockets that are located in the so-called "hinge region" of the identical protease chains, we computed a receptor-derived pharmacophore model, with which we retrieved fragment-like inhibitors from a screening compound pool. The most potent hit inhibited protease activity in vitro in a noncompetitive mode of action. Although attempts failed to crystallize this ligand bound to the enzyme, the study provides proof-of-concept for identifying innovative tool compounds for chemical biology by addressing flexible protein models with receptor pocket-derived pharmacophore screening.

Dengue Virus Serotype 1 Non-Structural Protein NS5 Expression Interferes with HIV Replication in a CD4+ T-Cell Line

The NS5 protein expression of certain flaviviruses, such as Dengue virus type 2, West Nile virus, Hepatitis C virus, and GB virus type C, is associated with a reduced in vitro human immunodeficiency virus (HIV) viral load. To evaluate the suppression effect of the dengue virus serotype 1 (DENV1) NS5 protein on HIV replication, a CD4+ T-cell line was transfected with a plasmid that contained the coding sequence of the DENV1 NS5 gene, and later, it was infected with HIV. DENV1 NS5 protein expression suppressed HIV replication by 28.88% (P < 0.005) on the fifth day compared with the control cells. These results confirm the suppression effect on HIV replication when the DENV1 NS5 protein is expressed in CD4+ T cells. Additional studies are needed to understand exactly how the DENV1 NS5 protein participates in the inhibition of HIV in vitro. HIV interaction with other infectious agents, especially in tropical regions, is associated with accelerated HIV/acquired immunodeficiency syndrome (AIDS) disease progression. However, Watt and others1 reported that HIV and dengue interaction was associated with a reduced HIV viral load. In regard to this finding, there are only four reports on HIV and DENV interaction in humans. The first study refers to an HIV patient infected with DENV1, in which a reduction in the viral load was observed during the coinfection.1 The second study describes an HIV patient with dengue hemorrhagic fever in Brazil,2 and the third report is a case series that includes five HIV patients infected with dengue in Singapore.3 Finally, a DENV3 and HIV coinfection in Cuba was described.4 Previous in vitro studies have reported that NS5 protein expression in certain flaviviruses, including DENV2, West Nile virus, Hepatitis C virus, Yellow Fever virus, and GB virus type C(GBV-C), is associated with HIV replication suppression in CD4+ T cells, which is attributed to an increase in the stromal cell-derived factor-1 (SDF-1) cytokine level expression.5 SDF-1 is the principle ligand for the CXCR4 coreceptor, and it blocks HIV fusion and entry into the CD4+ T lymphocytes.6 Despite the fact that these studies have suggested that the NS5 protein expression of DENV2 and other flaviviruses is associated with elevated levels of SDF-1 expression, the participation of the NS5 polyprotein during HIV suppression is not clear. The present study evaluated the effect of DENV1 NS5 protein expression on HIV replication in a CD4+ T-cell line. An in vitro study was carried out, in which Jurkat CD4+ T-cell cultures were infected with HIV. A DENV1 NS5 gene coding sequence was introduced into the experimental group, whereas the control group was only infected with HIV. HIV p24 antigen levels were measured as a viral replication estimator at the end of the experiment.

Clicking 3'-azidothymidine into novel potent inhibitors of human immunodeficiency virus.

3'-Azidothymidine (AZT) was the first approved antiviral for the treatment of human immunodeficiency virus (HIV). Reported efforts in clicking the 3'-azido group of AZT have not yielded 1,2,3-triazoles active against HIV or any other viruses. We report herein the first AZT-derived 1,2,3-triazoles with submicromolar potencies against HIV-1. The observed antiviral activities from the cytopathic effect (CPE) based assay were confirmed through a single replication cycle assay. Structure-activity-relationship (SAR) studies revealed two structural features key to antiviral activity: a bulky aromatic ring and the 1,5-substitution pattern on the triazole. Biochemical analysis of the corresponding triphosphates showed lower ATP-mediated nucleotide excision efficiency compared to AZT, which along with molecular modeling suggests a mechanism of preferred translocation of triazoles into the P-site of HIV reverse transcriptase (RT). This mechanism is corroborated with the observed reduction of fold resistance of the triazole analogue to an AZT-resistant HIV variant (9-fold compared to 56-fold with AZT).

Identification of myxobacteria-derived HIV inhibitors by a high-throughput two-step infectivity assay

BackgroundDrug-resistance and therapy failure due to drug-drug interactions are the main challenges in current treatment against Human Immunodeficiency Virus (HIV) infection. As such, there is a continuous need for the development of new and more potent anti-HIV drugs. Here we established a high-throughput screen based on the highly permissive TZM-bl cell line to identify novel HIV inhibitors. The assay allows discriminating compounds acting on early and/or late steps of the HIV replication cycle.ResultsThe platform was used to screen a unique library of secondary metabolites derived from myxobacteria. Several hits with good anti-HIV profiles were identified. Five of the initial hits were tested for their antiviral potency. Four myxobacterial compounds, sulfangolid C, soraphen F, epothilon D and spirangien B, showed EC50 values in the nM range with SI > 15. Interestingly, we found a high amount of overlapping hits compared with a previous screen for Hepatitis C Virus (HCV) using the same library.ConclusionThe unique structures and mode-of-actions of these natural compounds make myxobacteria an attractive source of chemicals for the development of broad-spectrum antivirals. Further biological and structural studies of our initial hits might help recognize smaller drug-like derivatives that in turn could be synthesized and further optimized.

English

Three analogues of formamidine disulphide (FMD) were synthesized as potential integrase inhibitor of human immunodeficiency virus (HIV). Piperonal, 3-Nitrobenz-aldehdye and 3,4,5-trimethoxybenzaldehyde, were respectively coupled with formamidine disulphide to prepare piperoformamidine disulphide (P-FMD), 3-Nitro-formamidine disulphide (N-FMD) and 3,4,5-trimethoxyformamidine disulphide (T-FMD). The structures of the three products were confirmed with infrared (IR),&nbsp;nuclear magnetic resonance&nbsp;(NMR) and&nbsp;mass spectrometry(MS) spectroscopic techniques, as reported. &nbsp; Key words:&nbsp;Human immunodeficiency virus (HIV), acquired immune deficiency syndrome (AIDS), formamidine disulphide (FMD).

Structure-Activity Relationship of 3-O-Acylated Betulinic Acid Derivatives Obtained by Enzymatic Synthesis as Anticancer Agents

Betulinic acid (1) is a naturally occurring pentacyclic lupane-type triterpenoid that possess multiple pharmacological activities including inhibition of human immunodeficiency virus (HIV), anti-bacterial, anti-malarial, anti-inflammatory, anthelmintic, antioxidant and anticancer properties [1]. The medical uses of betulinic acid in the pharmaceutical industry is strongly limited since it is insoluble in water, which causes a difficulty in preparation of injectable formulations for biological assays and decreases its bioavailability in the organism. The introduction of polar groups at the C-3 position such as phthalates in some cases, increases, its hydrosolubility and anticancer activity [2, 3]. In this study several 3-O-acyl-betulinic acid derivatives was prepared (Scheme 1) using various anhydrides and Novozym 435 as a biocatalyst. The cytotoxicity of betulinic acid derivatives was then evaluated on human lung carcinoma (A549) and human ovarian (CAOV3) cancer cell lines. On the basis of our in vitro cytotoxic results and the structure-activity relationship (SAR), we concluded that compounds (4), (6) and (8) were the most active compounds as compared to betulinic acid (1) against human lung carcinoma (A549). In an ovarian cancer cell line, all betulinic acid derivatives prepared showed weaker cytotoxicity than betulinic acid.

Interacción entre el virus de la inmunodeficiencia humana y el virus GB tipo-C durante el estado de co-infección

The human immunodeficiency virus (HIV) infection is one of the most important problems in public health. It is estimated that 3 3 million people are infected around the world. HIV and GBV-C share the same transmission route, being frequent the co-infection. Since both viruses replicate in CD4+ lymphocytes, recent studies have described an interaction. Decreasing of HIV viral load and higher CD4 counts have been observed in co-infected patients, leading a better clinical outcome. Nevertheless, some epidemiological studies have shown contradictory results. Additionally, in vitro models report inhibition of HIV by E1, E2, NS3 and NS5A GBV-C proteins, resulting in a decreasing of p24 antigen. This review summarizes the principal findings about co-infection and mechanisms that have been proposed for HIV-1 inhibition.

Predicting human immunodeficiency virus inhibitors using multi-dimensional Bayesian network classifiers

Our aim is to use multi-dimensional Bayesian network classifiers in order to predict the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and protease inhibitors given an input set of respective resistance mutations that an HIV patient carries. Multi-dimensional Bayesian network classifiers (MBCs) are probabilistic graphical models especially designed to solve multi-dimensional classification problems, where each input instance in the data set has to be assigned simultaneously to multiple output class variables that are not necessarily binary. In this paper, we introduce a new method, named MB-MBC, for learning MBCs from data by determining the Markov blanket around each class variable using the HITON algorithm. Our method is applied to both reverse transcriptase and protease data sets obtained from the Stanford HIV-1 database. Regarding the prediction of antiretroviral combination therapies, the experimental study shows promising results in terms of classification accuracy compared with state-of-the-art MBC learning algorithms. For reverse transcriptase inhibitors, we get 71% and 11% in mean and global accuracy, respectively; while for protease inhibitors, we get more than 84% and 31% in mean and global accuracy, respectively. In addition, the analysis of MBC graphical structures lets us gain insight into both known and novel interactions between reverse transcriptase and protease inhibitors and their respective resistance mutations. MB-MBC algorithm is a valuable tool to analyze the HIV-1 reverse transcriptase and protease inhibitors prediction problem and to discover interactions within and between these two classes of inhibitors.

Effective Inhibition of Human Immunodeficiency Virus 1 Replication by Engineered RNase P Ribozyme

Using an in vitro selection procedure, we have previously isolated RNase P ribozyme variants that efficiently cleave an mRNA sequence in vitro. In this study, a variant was used to target the HIV RNA sequence in the tat region. The variant cleaved the tat RNA sequence in vitro about 20 times more efficiently than the wild type ribozyme. Our results provide the first direct evidence that combined mutations at nucleotide 83 and 340 of RNase P catalytic RNA from Escherichia coli (G83 -> U83 and G340 -> A340) increase the overall efficiency of the ribozyme in cleaving an HIV RNA sequence. Moreover, the variant is more effective in reducing HIV-1 p24 expression and intracellular viral RNA level in cells than the wild type ribozyme. A reduction of about 90% in viral RNA level and a reduction of 150 fold in viral growth were observed in cells that expressed the variant, while a reduction of less than 10% was observed in cells that either did not express the ribozyme or produced a catalytically inactive ribozyme mutant. Thus, engineered ribozyme variants are effective in inhibiting HIV infection. These results also demonstrate the potential of engineering RNase P ribozymes for anti-HIV application.

Recent Advances in the Development of Small-Molecule Compounds Targeting HIV- 1 gp41 as Membrane Fusion Inhibitors

Over the past few years, remarkable progress has been made in the development of human immunodeficiency virus (HIV) membrane fusion inhibitors. The focus has been on peptide inhibitors, which were developed by mimicking HIV sequences; however, these types of inhibitors generally lack oral bioavailability and are expensive. Therefore, development of small-molecule inhibitors has gained importance and recently progressed. This paper reviews the rapid advancements in the development of small-molecule HIV inhibitors over the last decade. Keywords: Coiled-coil, docking simulation, gp41, heptad repeat, HIV, membrane fusion, quantitative structure-activity relationship, smallmolecule inhibitors, HAART, drug targets, bioavailability

Organic Crop Management Enhances Chicoric Acid Content in Lettuce

L- chicoric acid is a dominant phenolic compound in lettuce (Lactuca sativa L.) and has been shown to accumulate in response to many abiotic stresses and crop management practices. It is a potent inhibitor of human immunodeficiency virus (HIV-1) integrase needed for the replication of this virus and for the productive infection of the host cell. L- chicoric acid has been found to act synergistically in combination with anti-HIV drugs used for treating acquired immuno-deficiency disorder (AIDS). We show in this study that organic management practices increase the chicoric acid content by nearly 2-fold compared to conventional management practices while they did not have a significant effect on the overall accumulation of phenolic compounds and antioxidants. Similar increase was observed in quercetin-3-O-glucoside under organic management. In addition, pre-plant fertilization decreased the levels of many phenolic compounds including chicoric acid under organic management unlike under conventional management. However, organically managed crop without pre-plant fertilization had better growth and produced about 2.5 times higher yield and higher chicoric acid content than did the conventionally managed crop. Thus, the results show that long term organic crop management practices, but avoiding pre-plant fertilization, can significantly enhance the yield of antiretroviral agent chicoric acid in lettuce.

In silico screening of indinavir-based compounds targeting proteolytic activity in HIV PR: binding pocket fit approach

The intense research on small molecule inhibitors of Human immunodeficiency virus (HIV)-protease (PR) has produced a diverse class of chemical scaffolds which includes clinically available HIV PR inhibitors (PRI). Till now, these inhibitors are insignificant for targeting proteolytic activity and few drug molecules on alterations can enhance the inhibition of PR enzyme. Here, we developed a method for screening of new hits from Cambridge structural database, based on binding mode of indinavir interaction participating atoms. Knowledge-based ligand screening technique approximately informs that new hits are also having same binding mode-like indinavir interaction patterns. Considering the importance of ligand fitting in binding pocket, we developed induced-fit models for each compound and we obtained accurate energy values in terms of binding and interaction energy. We found that newly search molecules are interacting better than known drug—indinavir and these new compounds are comparatively having better drug-like property. Finally, we demonstrated that pocket specific docking, energy utilization, interactions, and ADME for screened compounds are showing new hit compounds of indinavir are better HIV PRI and these new compounds can also show better activity in in vivo and in vitro conditions.

Adsorption of Chicago Sky Blue on the Langmuir Monolayer and Langmuir-Blodgett Films of Octadecylamine

This paper reports the incorporation of an inhibitor of Human Immunodeficiency Virus (HIV), viz. Chicago Sky Blue (CSB) dye within an insoluble cationic octadecylamine (ODA) Langmuir monolayer. A surface pressure-area isotherm study confirmed the strong interaction between long chain amine and CSB dye. At higher surface pressure, CSB molecules tend to squeeze out from the octadecylamine monolayer. SEM study confirms this observation. Adsorption kinetics shows that the amount of dye adsorbed depends on the concentration of the dye present in the subphase. It was observed that the absorption process mainly occurred due to the electrostatic interaction between the cationic amino group of long chain amine and the sulphonate group of CSB dye. UV-Vis absorption spectroscopic study indicates the formation of aggregates of CSB dye in the mixed (ODA-CSB) LB films.

208. Inhibition of Human Immunodeficiency Virus (HIV) Type 1 Replication through Expression of RNAi Effectors Targeting HIV-Dependency Factor HTATSF1

208. Inhibition of Human Immunodeficiency Virus (HIV) Type 1 Replication through Expression of RNAi Effectors Targeting HIV-Dependency Factor HTATSF1

Evaluation of Antifungal Activity of Medicinal Plant Extracts Against Oral Candida albicans and Proteinases

Proteinases produced by Candida albicans are one kind of virulence factor expressed that contribute to adherence and invasion of host tissue. Proteinase inhibitor of human immunodeficiency virus in experimental candidiasis suggested reduction in fungal infection, and medicinal plants could be a source of alternative agent to prevent diseases. In this study, we investigated the production of proteinases by C. albicans from clinical isolates and the action of plant extracts against strains of C. albicans and its synthesized proteinases, comparing with antifungal fluconazole and amphotericin B and proteinase inhibitors pepstatin A, amprenavir, and ritonavir. The results reported here showed that these extracts have a certain kind of action and that the search for new antifungal agents could be found at the plants.

Effect of Low-Dose Omeprazole (20 mg Daily) on the Pharmacokinetics of Multiple-Dose Atazanavir With Ritonavir in Healthy Subjects

Atazanavir, a potent protease inhibitor of human immunodeficiency virus (HIV), exhibits pH-dependent solubility. Previous studies have indicated that coadministration with omeprazole 40 mg once daily significantly decreased atazanavir exposure by approximately 75%. Concomitant use of omeprazole and atazanavir is currently not recommended. This study investigated a clinically effective, low dose of omeprazole (20 mg daily) on atazanavir pharmacokinetics in 56 healthy volunteers given atazanavir/ritonavir 300/100 and 400/100 mg once daily. All atazanavir/ritonavir plus omeprazole combinations resulted in atazanavir area under the concentration-time curve (AUC) and trough concentrations (C(min)) comparable to or exceeding those observed with atazanavir 400 mg without omeprazole. Compared with atazanavir/ritonavir 300/100 mg without omeprazole, atazanavir/ritonavir 300/100 mg plus omeprazole reduced atazanavir AUC and C(min) by 42% and 46%, respectively. Increasing the atazanavir/ritonavir dose to 400/100 mg attenuated the effect of omeprazole, resulting in approximately 30% lower atazanavir C(min), with all individual C(min) values exceeded by greater than 10-fold the population mean protein binding-adjusted EC(90) against wild-type HIV. The effect of omeprazole on atazanavir/ritonavir 400/100 mg was similar whether given 1 hour prior to atazanavir/ritonavir or separated by 12 hours. No unexpected adverse events were noted. This study found that omeprazole 20 mg once daily has significantly less profound effects on atazanavir pharmacokinetics than previously observed with omeprazole 40 mg.

A novel trifunctional IgG-like bispecific antibody to inhibit HIV-1 infection and enhance lysis of HIV by targeting activation of complement.

BackgroundThe complement system is not only a key component of innate immunity but also provides a first line of defense against invading pathogens, especially for viral pathogens. Human immunodeficiency virus (HIV), however, possesses several mechanisms to evade complement-mediated lysis (CoML) and exploit the complement system to enhance viral infectivity. Responsible for this intrinsic resistance against complement-mediated virolysis are complement regulatory membrane proteins derived from the host cell that inherently downregulates complement activation at several stages of the cascade. In addition, HIV is protected from complement-mediated lysis by binding soluble factor H (fH) through the viral envelope proteins, gp120 and gp41. Whereas inhibition of complement activity is the desired outcome in the vast majority of therapeutic approaches, there is a broader potential for complement-mediated inhibition of HIV by complement local stimulation.Presentation of the hypothesisOur previous studies have proven that the complement-mediated antibody-dependent enhancement of HIV infection is mediated by the association of complement receptor type 2 bound to the C3 fragment and deposited on the surface of HIV virions. Thus, we hypothesize that another new activator of complement, consisting of two dsFv (against gp120 and against C3d respectively) linked to a complement-activating human IgG1 Fc domain ((anti-gp120 × anti-C3d)-Fc), can not only target and amplify complement activation on HIV virions for enhancing the efficiency of HIV lysis, but also reduce the infectivity of HIV through blocking the gp120 and C3d on the surface of HIV.Testing the hypothesisOur hypothesis was tested using cell-free HIV-1 virions cultivated in vitro and assessment of virus opsonization was performed by incubating appropriate dilutions of virus with medium containing normal human serum and purified (anti-gp120 × anti-C3d)-Fc proteins. As a control group, viruses were incubated with normal human serum under the same conditions. Virus neutralization assays were used to estimate the degree of (anti-gp120 × anti-C3d)-Fc lysis of HIV compared to untreated virus.Implications of the hypothesisThe targeted complement activator, (anti-gp120 × anti-C3d)-Fc, can be used as a novel approach to HIV therapy by abrogating the complement-enhanced HIV infection of cells.

Synthesis and evaluation of β-carboline derivatives as inhibitors of human immunodeficiency virus

A series of β-carboline derivatives were synthesized by utilizing aromatization and chemoselective alkylation method recently reported from our laboratory. Synthesized derivatives were evaluated for anti-HIV activity in human CD4+ T cell line (CEM-GFP) infected with HIV-1 NL4.3 virus. 1-Formyl-β-carboline-3-carbxylic acid methyl ester (15) showed inhibition of human immunodeficiency virus at IC50=2.9μM.

ChemInform Abstract: Synthesis and Evaluation of 3′‐Azido‐2′,3′‐dideoxypurine Nucleosides as Inhibitors of Human Immunodeficiency Virus.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A simple fluorescence based assay for quantification of human immunodeficiency virus particle release

BackgroundThe assembly and release of human immunodeficiency virus (HIV) particles from infected cells represent attractive, but not yet exploited targets for antiretroviral therapy. The availability of simple methods to measure the efficiency of these replication steps in tissue culture would facilitate the identification of host factors essential for these processes as well as the screening for lead compounds acting as specific inhibitors of particle formation. We describe here the development of a rapid cell based assay for quantification of human immunodeficiency virus type 1 (HIV-1) particle assembly and/or release.ResultsUsing a fluorescently labelled HIV-derivative, which carries an eYFP domain within the main viral structural protein Gag in the complete viral protein context, the release of virus like particles could be monitored by directly measuring the fluorescence intensity of the tissue culture supernatant. Intracellular Gag was quantitated in parallel by direct fluorescence analysis of cell lysates, allowing us to normalize for Gag expression efficiency. The assay was validated by comparison with p24 capsid ELISA measurements, a standard method for quantifying HIV-1 particles. Optimization of conditions allowed the robust detection of particle amounts corresponding to 50 ng p24/ml in medium by fluorescence spectroscopy. Further adaptation to a multi-well format rendered the assay suitable for medium or high throughput screening of siRNA libraries to identify host cell factors involved in late stages of HIV replication, as well as for random screening approaches to search for potential inhibitors of HIV-1 assembly or release.ConclusionsThe fast and simple fluorescence based quantification of HIV particle release yielded reproducible results which were comparable to the well established ELISA measurements, while in addition allowing the parallel determination of intracellular Gag expression. The protocols described here can be used for screening of siRNA libraries or chemical compounds, respectively, for inhibition of HIV in a 96-well format.