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Integrase inhibitors and cellular immunity suppress retroviral replication in rhesus macaques.

We describe the efficacy of L-870812, an inhibitor of HIV-1 and SIV integrase, in rhesus macaques infected with the simian-human immunodeficiency virus (SHIV) 89.6P. When initiated before CD4 cell depletion, L-870812 therapy mediated a sustained suppression of viremia, preserving CD4 levels and permitting the induction of virus-specific cellular immunity. L-870812 was also active in chronic infection; however, the magnitude and durability of the effect varied in conjunction with the pretreatment immune response and viral load. These studies demonstrate integrase inhibitor activity in vivo and suggest that cellular immunity facilitates chemotherapeutic efficacy in retroviral infections.

Acquired Immunodeficiency Syndrome↗

Self-association of an amphipathic helix peptide inhibitor of HIV-1 integrase assessed by electro spray ionization mass spectrometry in trifluoroethanol/water mixtures.

Establishing the auto-associative properties of a molecule in solution can be important for determination of its structure and function. EAA26 (VESMNEELKKIIAQVRAQAEHLKTAY) has been designed to inhibit HIV-1 integrase via formation of a stable coiled-coil structure with a nearly homologous segment in the enzyme. The latter catalyzes the permanent incorporation of a DNA copy of the retrovirus genome into host cell DNA, and is thus essential to the life of the retrovirus. This makes integrase an obvious drug target in the therapy of AIDS. The present work has demonstrated, using electrospray ionization mass spectrometry (ESI-MS), that EAA26 is monomeric in pure water, and tetrameric and dimeric at respectively low and medium concentrations of 2,2,2-trifluoroethanol (TFE), and again monomeric at higher TFE concentrations. Thus, the apolar solvent TFE may contribute to either stabilization or disruption of the intermolecular hydrophobic contacts depending on its concentration in aqueous solution. Previous NMR and ultracentifugation results are thus confirmed, indicating the reliability of ESI-MS for defining the self-association state of biologically relevant peptides in both water and organic-water solutions.

Amino Acid Sequence↗

Rational design of novel diketoacid-containing ferrocene inhibitors of HIV-1 integrase.

Molecular interaction field, density functional, and docking studies of novel potential ferrocene inhibitors of HIV-1 integrase (IN) are reported. The high docking scores, analysis of the ligand-receptor interactions in the active site as well as the molecular interaction potential calculations at the binding site of the receptor indicate important features for novel HIV-1 IN inhibitors. We also confirm in this work a novel binding trench in HIV-1 integrase, recently reported in a theoretical work by other authors. This observation may be interesting since the lack of detailed structural information about IN-ligand interactions has hampered the design of IN inhibitors. Our proposed ligands are open to experimental synthesis and testing.

Acids↗

2,6-Bis(3,4,5-trihydroxybenzylydene) derivatives of cyclohexanone: novel potent HIV-1 integrase inhibitors that prevent HIV-1 multiplication in cell-based assays.

A number of 2,6-bisbenzylidenecyclohexane-1-one derivatives have been synthesized and tested as HIV-1 integrase (IN) inhibitors with the aim of obtaining compounds capable to elicit antiviral activity at non-cytotoxic concentrations in cell-based assays. 3,5-Bis(3,4,5-trihydroxybenzylidene)-4-oxocyclohexaneacetic acid (20d) resulted one of the most potent and selective derivatives in acutely infected MT-4 cells (EC(50) and CC(50) values of 2 and 40 microM, respectively). In enzyme assays with recombinant HIV-1 integrase (rIN), this compound proved able to inhibit both 3'-processing and disintegration with IC(50) values of 0.2 and 0.5 microM, respectively. In order to develop a model capable to predict the anti HIV-IN activity and useful to design novel derivatives, we performed a comparative molecular field analysis (CoMFA) like 3-D-QSAR. In our model the ligands were described quantitatively in the GRID program, and the model was optimized by selecting only the most informative variables in the GOLPE program. We found the predictive ability of the model to increase significantly when the number of variables was reduced from 20,925 to 1327. A Q(2) of 0.73 was obtained with the final model, confirming the predictive ability of the model. By studying the PLS coefficients in informative 3-D contour plots, ideas for the synthesis of new compounds could be generated.

Anti-HIV Agents↗

Design, synthesis, and anti-integrase activity of catechol-DKA hybrids.

Following the discovery of diketoacid-containing compounds as HIV-1 integrase (IN) inhibitors, a plethora of new molecules have been published leading to four drugs under clinical trial. In an attempt to rationally design new dimeric diketoacids (DKAs) targeting two divalent metal ions on the active site of IN, potent inhibitors against purified IN were found with varied selectivity for strand transfer. In this context, we designed and synthesized a new series of catechol-DKA hybrids. These compounds presented micromolar anti-integrase activities with moderate antiviral properties.

Acids↗

Catechol-substituted L-chicoric acid analogues as HIV integrase inhibitors.

HIV integrase catalyzes the integration of HIV DNA copy into the host cell DNA, which is essential for the production of progeny viruses. L-Chicoric acid and dicaffeoylquinic acids, isolated from plants, are well known potent inhibitors of HIV integrase. The common structural features of these inhibitors are caffeic acid derivatives connected to tartaric acid or quinic acid through ester bonds. In the present study, we have synthesized and tested the inhibitory activities of a new type of HIV IN inhibitors, which has catechol groups in place of caffeoyl groups in the structure of L-chicoric acid. Upon substitution of catechol groups at succinic acid, pyrrole-dicarboxylic acid, maleimide or maleic anhydride, the inhibitory activities (IC(50)=3.8-23.6 microM) were retained or remarkably increased when compared to parent compound L-chicoric acid (IC(50)=13.7 microM).

Caffeic Acids↗

Design and synthesis of photoactivatable aryl diketo acid-containing HIV-1 integrase inhibitors as potential affinity probes.

Aryl diketo acids (ADKs) represent an important new class of HIV-1 integrase (IN) inhibitors. In order to facilitate examination of the structural basis underlying IN?ADK interaction, biphenyl ketone and phenyl azide photophores were incorporated into ADK structures. Of particular note is the novel dual utilization of azide and phenyketone moieties for both enzyme recognition and for crosslinking. The resulting analogues maintained low micromolar inhibitory potency against IN in recombinant in vitro assays. These potential HIV-1 integrase photoaffinity labels may provide useful tools for studying enzyme interactions of the ADK inhibitor class.

Drug Design↗

Inhibition of the strand transfer step of HIV-1 integrase by non-natural dinucleotides.

New, non-natural dinucleotide 5'-monophosphates, with a surrogate isonucleoside component of l-related stereochemistry at the 'terminal' position, have been synthesized. Structures of 2a-c were confirmed by multinuclear NMR spectra ((1)H, (13)C, (31)P, COSY), UV hypochromicity and FAB HRMS data. These compounds are totally resistant to cleavage by 3'- and 5'-exonucleases. The dinucleotides showed remarkable selectivity for inhibition of the strand transfer step of HIV-1 integrase. To the best of our knowledge, these compounds represent only the second example of selective strand transfer inhibitors of HIV integrase.

Dinucleoside Phosphates↗

Design, synthesis, and biological evaluation of novel tricyclic HIV-1 integrase inhibitors by modification of its pyridine ring.

This communication details both the syntheses and biological evaluation of a novel class of HIV-1 integrase inhibitors. When the quinoline moiety is replaced with the quinoxoline moiety, the antiviral activity is significantly compromised. Similarly, introduction of imidazole to replace the pyridine ring is deleterious to the potency of the compound against the enzyme. Substitution at the 3-position of the pyridine has been investigated. The presence of the pyridine ring in the tricyclic core is preferred for antiviral activity against HIV integrase.

Drug Design↗

Synthesis of styrylbenzofuran derivatives as styrylquinoline analogues for HIV-1 integrase inhibitor.

A series of styrylbenzofuran derivatives (8a-i) as styrylquinoline isosters were efficiently prepared by Wittig reaction and evaluated for inhibitory activity against HIV-1 integrase. In this series, compounds 8g, 8h and 8i containing a free catechol ring showed moderate inhibitory activities (IC50= approximately 40 microM) against HIV-1 integrase, while less than the corresponding styrylquinoline compound (I).

Benzofurans↗

Cre-loaded integrase-defective lentiviral vectors for targeted cassette exchange in CHO cells.

Genome-modifying enzymes, such as recombinases and CRISPR-associated nucleases, enable targeted gene insertion when delivered transiently to minimize off-target effects. Precise genome engineering requires controlled enzyme activity, as well as efficient donor DNA transfer. Integrase-defective lentiviral vectors (IDLVs) provide a promising platform for transient episomal DNA transfer; however, their integration efficiency depends on complementary genome-targeting strategies. Here, we engineered Cre-loaded IDLVs (Cre-IDLVs) that co-package lentiviral vector genomes together with bioactive Cre recombinase. Cre was inserted into the Gag region of an integrase-defective gag-pol construct, allowing for efficient encapsidation and protease-mediated release during virion maturation without compromising the viral titer. The resulting particles carried donor cassettes flanked by heterospecific loxP sites. When applied to CHO founder cells harboring compatible genomic loxP landing pads, Cre-IDLVs efficiently mediated recombination-mediated cassette exchange, producing the highest number of G418-resistant colonies among the plasmid ratios tested. Genomic PCR and sequencing confirmed precise locus-specific insertion without detectable random integration in the analyzed clones. These findings establish Cre-IDLVs as a streamlined dual-delivery platform that couples transient recombinase activity with episomal donor DNA transfer. This hybrid lentiviral strategy provides a programmable approach for controlled and site-specific genome modification in mammalian cells.

Integrases↗

Cluster analysis and three-dimensional QSAR studies of HIV-1 integrase inhibitors.

Three-dimensional quantitative structure-activity relationship (3D QSAR) and cluster analysis were applied to a variety of HIV-1 integrase inhibitors. One structure was chosen from each of 11 classes of inhibitors to represent the whole class in descriptor-based cluster analysis. The 11 classes of inhibitors were classified into two groups. The molecular field analysis (MFA) models for these two clusters had r2 values of 0.90 and 0.95 and q2 values of 0.85 and 0.91 that were noticeably enhanced from those of conventional QSAR models. The five test compounds, which were proposed to have a common binding site near the metal in HIV-1 integrase based on docking studies by Sotriffer et al., were utilized to compare the predictive capability of MFA and conventional QSAR models. Among these five compounds, only L-chicoric acid belongs to cluster 1 and the other four belong to cluster 2. MFA models give better overall predictions and more importantly the activity of these test compounds is better predicted by the MFA model derived from the cluster each test compound belongs to. The necessity of dividing the inhibitors into two groups to obtain predictive QSAR models supports the likelihood of two separate binding sites.

Cluster Analysis↗

Retroviral integrase inhibitors year 2000: update and perspectives.

HIV-1 integrase is an essential enzyme for retroviral replication and a rational target for the design of anti-AIDS drugs. A number of inhibitors have been reported in the past 8 years. This review focuses on the recent developments in the past 2 years. There are now several inhibitors with known sites of actions and antiviral activity. The challenge is to convert these leads into drugs that will selectively target integrase in vivo, and can be added to our antiviral armamentarium.

Anti-HIV Agents↗

Why have ten or so nontoxic, retrovirus integrase inhibitors not been made available for AIDS treatment? A ten-year experience [correction of experiment] must liberate them.

We detected in 1989, with the inhibitor test of proviral insertion into c-erb B erythroblastosis, two retrovirus integrase inhibitors: hydroxy-methyl-ellipticine and acriflavine. They have been used for ten years in AIDS patients with high efficacy and no toxicity. Since vitamin B12 and cobalt, which it contains, have been detected as HIV1-integrase inhibitors by an in-vitro test, we have also used vitamin B12 (combined with folic acid), whose clinical action has been remarkable. Ten or so other compounds have been detected by such in-vitro tests, among which there are many compounds (such as flavones) which are used in many conditions and are not toxic.

Acquired Immunodeficiency Syndrome↗

Recognition and inhibition of HIV integrase by a novel dinucleotide.

The viral enzyme, HIV integrase, is involved in the integration of viral DNA into host cell DNA. In the quest for a small nucleotide system with nuclease stability of the internucleotide phosphate bond and critical structural features for recognition and inhibition of HIV-1 integrase, we have discovered a conceptually novel dinucleotide, pIsodApdC, which is a potent inhibitor of this key viral enzyme.

HIV Integrase↗

Integracides: tetracyclic triterpenoid inhibitors of HIV-1 integrase produced by Fusarium sp.

HIV-1 integrase is a critical enzyme in the replication of HIV-1. It is absent in the host cells and therefore is a good target for treatment of HIV-1 infections. Integracides are members of the tetracyclic triterpenoids family that were isolated from the fermentation broth of a Fusarium sp. Integracide A, a sulfated ester, exhibited significant inhibitory activity against strand transfer reaction of HIV-1 integrase. The discovery, structure elucidation including single crystal X-ray structure and HIV-1 inhibitory activity of these compounds are described.

Crystallography, X-Ray↗

Major and minor groove contacts in retroviral integrase-LTR interactions.

The 3'-processing activities of HIV-1, HTLV-2, and M-MuLV integrases (INs) with their corresponding U5 end of the viral DNA molecule were examined to define functional group determinants of U5 terminus recognition and catalysis. Nucleotide analogues were incorporated into the U5 terminus to produce conservative modifications in the surface of the major and/or minor grooves to map the hydrogen-bonding contacts required for LTR-IN interaction. Specifically, the phylogenetically conserved CA (positions 4 and 3, respectively) and the 5'-proximal nucleotide (position 5) were replaced with base analogues in plus and/or minus strands. For each integrase, similar major and minor groove contacts were identified in the guanine and adenine of the conserved CA/GT. Overall, perturbances in the minor groove resulted in a greater decrease in 3'-processing activity than the major groove substitutions. Additionally for HIV-1 and HTLV-2 INs, we observed an increase in the 3'-processing activity with an O4-MeThy substitution at position 3 of the minus strand. O4-MeThy may act to destabilize Watson-Crick base pairing and in doing so provide these INs with a more favorable interaction with the adjacent scissile bond. At position 5, a substantial divergence among the three INs was noted in the functional groups required for 3'-processing activity, thereby supporting the role of this position in providing some level of substrate specificity.

Base Sequence↗

Eigen value analysis of HIV-1 integrase inhibitors.

A three-dimensional quantitative structure activity relationship using the eigen value analysis (EVA) paradigm applied to 41 HIV-1 integrase inhibitors that inhibit integrase mediated cleavage (3'-processing step) and integration (3'-strand transfer step) in vitro was performed. The training set consisted of 35 molecules from five structurally diverse classes: salicylhydrazines, lichen acids, coumarins, quinones, and thiazolothiazepines. Models derived using semiempirical (MOPAC AM1 and PM3) calculated normal-mode frequencies were compared. The predictive ability of each resultant model was evaluated using a test set comprised of six molecules belonging to a different structural class: hydrazides. Models derived using AM1 method showed considerable internal as well as external predictivity (r(2)(cv) = 0.806, r(2)(pred) = 0.761 for 3'-processing and r(2)(cv) = 0.677, r(2)(pred) = 0.591 for 3'-strand transfer).

HIV Integrase↗