Publications

(R)-9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine is a potent inhibitor of feline immunodeficiency virus infection

The antiviral efficacy of acyclic nucleoside phosphonates, including 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and (R)-9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine [(R)-PMPDAP] against feline immunodeficiency virus (FIV) infection was determined. (R)-PMPDAP showed the highest selectivity index (> 2,000) in vitro. Treatment of experimentally FIV-infected asymptomatic cats with PMEA or (R)-PMPDAP had no effect on the CD4+/CD8+ ratio. However, mean plasma viral RNA concentrations decreased significantly in the (R)-PMPDAP-treated cats. Our data show that, in comparison to PMEA, (R)-PMPDAP is a more potent and less toxic inhibitor of FIV replication both in vitro and in vivo.

Cell Type-Dependent Effect of Sodium Valproate on Human Immunodeficiency Virus Type 1 Replication <i>in Vitro</i>

Sodium valproate (VPA), a simple branched-chain fatty acid that has anticonvulsant activity and is used in the treatment of many forms of epilepsy, has been reported to stimulate human immunodeficiency virus (HIV) type 1 replication in acutely infected CEM and chronically infected U1 cells (Chemico-Biological Interactions 1994;91:111-121). When attempting to reproduce and extend these findings, we confirmed that VPA is able to stimulate HIV-1(IIIB) replication in acutely infected CEM and C8166 T lymphocytic cell lines and chronically infected ACH-2 and U937/IIIB/LAI cells in a concentration-dependent manner. The stimulatory effect of VPA on HIV replication in CEM cells was not increased by pretreatment of the cells with VPA for 24 hr before infection. However, we could not detect any stimulatory effect of VPA on HIV-1(IIIB) replication in acutely infected peripheral blood mononuclear cells (PBMCs), MT-4, MT-2, HUT-78, and MOLT-4 (clone 8) cells and in chronically infected HUT-78/IIIB/LAI cells. The stimulatory effect by VPA under certain conditions (see above) may be ascribed to an enhanced HIV transcription, as VPA was found to enhance the HIV long terminal repeat (LTR)-directed expression of beta-galactosidase in transiently transfected HLtat, P4, and COS7 cells. VPA did not enhance beta-galactoside expression mediated by the cytomegalovirus (CMV) promoter. VPA did not affect HIV-induced syncytium formation. Nor had VPA any direct inactivating effect on HIV.

Antiviral effects of dihydroxypropyladenine ((RS)-DHPA) and bromovinyldeoxyuridine (BVDU) on plant viruses

Preparation and anti-HIV activities of aurintricarboxylic acid fractions and analogs: direct correlation of antiviral potency with molecular weight

Aurintricarboxylic acid (ATA) was fractionated by a combination of dialysis, ultrafiltration, and gel permeation chromatography. The number average and weight average molecular weights of the ATA fractions were determined by the universal calibration method. The sulfonic acid analogue of ATA was prepared and separated in high and low molecular weight fractions. The phosphonic acid analogue of ATA was also synthesized. All of the ATA fractions were tested for prevention of the cytopathic effect of HIV-1 and HIV-2 in MT-4 cell culture as well as against HIV-1 in CEM cell culture. The abilities of the fractions and analogues to inhibit syncytium formation between HIV-1- and HIV-2-infected HUT-78 cells and uninfected MOLT-4 cells were evaluated. In addition, the fractions and analogues were tested for cytotoxicity in mock-infected MT-4 cells, prevention of the binding of the OKT4A monoclonal antibody to the CD4 receptor, inhibition of the binding of anti-gp120 monoclonal antibody to gp120, inhibition of attachment of HIV-1 virions to MT-4 cells, and inhibition of HIV-1 reverse transcriptase. In all of these assays except cytotoxicity, there was a correlation of potency with molecular weight. The higher the molecular weight, the higher the activity. Several of the lower molecular weight fractions of ATA, which bound to gp120 but not to CD4, prevented HIV-1 and HIV-2 cytopathicity. A similar profile was observed for the phosphonic acid analogue of ATA and the lower molecular weight fraction of the sulfonic acid analogue. The results on the ATA fractions indicate that the binding of ATA to gp120 in the absence of CD4 binding is sufficient for anti-HIV activity. The active compounds bind more avidly to gp120 than to CD4. The anti-HIV activity of the ATA fractions is due to inhibition of virus binding due to an interference with the gp120-CD4 interaction.

CCDC 207803: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

ChemInform Abstract: Synthesis of Novel 5′‐Substituted TSAO‐T Analogues with anti‐HIV‐1 Activity.

Abstract ChemInform 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.

Tetrazolium-based plaque assay for HIV-1 and HIV-2, and its use in the evaluation of antiviral compounds

Fluoro-substitution and 7-alkylation/arylalkylation as prospective modifications of biologically active 6-aryl derivatives of TACV and TGCV

Differential activities of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine derivatives against different human immunodeficiency virus type 1 mutant strains

A series of 23 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine derivatives that were highly potent inhibitors of wild-type human immunodeficiency virus type 1 strain IIIB (HIV-1/IIIB) replication in CEM cells were evaluated against a panel of HIV-1 mutant strains containing the replacement of leucine by isoleucine at position 100 (100-Leu-->Ile), 103-Lys-->Asn, 106-Val-->Ala, 138-Glu-->Lys, 181-Tyr-->Cys, 181-Tyr-->Ile, or 188-Tyr-->His in their reverse transcriptase (RT). A different structure-antiviral activity relationship was found, depending on the nature of the mutated amino acid in the HIV-1 RT. The results show that 5-ethyl-1-ethoxymethyl-6-(3,5-dimethylbenzyl)uracil, 5-ethyl-1-ethoxymethyl-6-(3,5-dimethylphenylthio)uracil, and 5-ethyl-1-ethoxymethyl-6-(3,5-dimethylphenylthio)-2-thiouracil remain active against the majority of viruses containing single mutations which confer resistance to nonnucleoside RT inhibitors.

ChemInform Abstract: Synthesis of Some Novel Thiosemicarbazone Derivatives Having Anticancer, anti‐HIV as well as Antibacterial Activity.

Abstract Some new thiosemicarbazones containing benzimidazole moiety (VI) are synthesized and screened for their ability to inhibit the growth of 60 human cancer cell lines, in vitro replication on HIV virus strains as well as inhibition capacity for several bacterial strains.

SIV/HIV-1 Hybrid Virus Expressing the Reverse Transcriptase Gene of HIV-1 Remains Sensitive to HIV-1-Specific Reverse Transcriptase Inhibitors After Passage in Rhesus Macaques

We have previously described an animal model for the therapy of human immunodeficiency virus type 1 (HIV-1) infection with HIV-1-specific reverse transcriptase (RT) inhibitors based on a simian immunodeficiency virus (SIV), in which the RT gene of SIV was replaced by the RT gene of HIV-1. In vitro, replication of the hybrid virus, RT-SHIV, was delayed compared with parental SIV. RT-SHIV could induce AIDS-like symptoms and pathologic alterations in rhesus macaques. Characterization of re-isolates recovered from RT-SHIV-infected macaques one-half year after infection revealed that the re-isolates replicated with kinetics similar to those of SIV. Inefficient processing of the Gag-Pol precursor of RT-SHIV may be one reason for the retarded growth of RT-SHIV, because the protease cleavage site between the protease gene and the RT gene was frequently mutated in the RT-SHIV re-isolates. Adaptation of RT-SHIV to the growth in macaques did not result in a relevant loss of sensitivity to nonnucleoside RT inhibitors (NNRTIs). However, because a minor sub-population of the RT-SHIV re-isolates contained a mutation conferring low-level resistance to ddI and ddC, the RT-SHIV/macaque model may underestimate the efficacy of these drugs. Nevertheless, this report further supports the suitability, reliability, and usefulness of the RT-SHIV/macaque model to investigate the antiviral properties of most RT inhibitors in an in vivo setting.

Thymidylate synthetase-deficient mouse FM3A mammary carcinoma cell line as a tool for studying the thymidine salvage pathway and the incorporation of thymidine analogues into host cell DNA

A thymidylate (dTMP) synthetase-deficient murine mammary carcinoma cell line (FM3A/TS-), auxotrophic for thymidine (dThd), proved extremely useful for studying the dependence of cell growth on the exogenous supply of dThd, the relation between cell growth and DNA synthesis, and the ability of a series of 25 5-substituted 2'-deoxyuridines (dUrd) to substitute for dThd in sustaining cell growth. FM3A/TS-cells did not proliferate unless dThd was supplied to the cell culture medium. The 5-halogenated dUrd derivatives 5-chloro-dUrd, 5-bromo-dUrd and 5-iodo-d Urd also sustained FM3A/TS- cell growth. The extents of incorporation of [methyl-3H]dThd and 5-iodo-[6-3H]dUrd into DNA were closely correlated with their stimulatory effects on FM3A/TS- cell growth. This suggests that the stimulatory effects of the dUrd analogues on the growth rate of FM3A/TS- cells may be considered as evidence for their incorporation into host cell DNA. Based on this premise it is postulated that, in addition to 5-chloro-dUrd, 5-bromo-dUrd, 5-iodo-dUrd and dThd itself, the following dThd analogues are also incorporated into FM3A/TS- cell DNA (in order of the extent to which they are incorporated): 5-hydroxy-dUrd greater than 5-propynyloxy-dUrd greater than 5-ethyl-dUrd greater than 5-ethynyl-dUrd approximately 5-vinyl-dUrd. Thus, the dTMP synthetase-deficient FM3A/TS- cell line represents a unique system to dissociate the de novo and salvage pathways of dTMP biosynthesis and to distinguish those dUrd analogues that are incorporated into DNA from those that are not.

Herpes Simplex Acyclovir-Resistant Mutant in Experimental Keratouveitis

Acyclovir is a potent and selective antiviral agent. Unfortunately, drug-resistant (acyclovir-resistant) mutants have already been reported in herpes simplex virus type 1 (HSV-1) orofacial infections. We have developed a laboratory acyclovir-resistant HSV-1 mutant. The natural course of acyclovir-resistant HSV-1 keratitis was found to be less virulent than that observed in wild type HSV-1 keratitis, but the rate of ganglionic latency was as high as that induced by the parental strain. In vitro studies and in vivo observation of rabbit corneas infected with acyclovir-resistant HSV-1 both demonstrated a significant sensitivity to vidarabine and bromovinyldeoxyuridine ([E]-5-[2-bromovinyl]-2'-deoxyuridine). The thymidine kinase activity of the acyclovir-resistant mutant was 69% of that of the wild type HSV-1.

Intracellular Metabolism of the N7-Substituted Acyclic Nucleoside Analog 2-Amino-7-(1,3-dihydroxy-2-propoxymethyl)purine, a Potent Inhibitor of Herpesvirus Replication

Reflections on the Rega Institute for Medical Research, at the fiftieth anniversary of the Rega Stichting vzw (Rega Instituut vzw, Rega Foundation)

The idea to start the Rega Foundation was conceived in 1971 at an informal meeting organized by Prof. Piet De Somer (where Prof. Alfons Billiau, Prof. André Vlerick and I were also present), before the Foundation was formally created in 1972. From the early years some antiviral compounds, such as BVDU and the aminoacyl esters of acyclovir (from which ultimately valacyclovir evolved) originated. The advent of AIDS in 1981 and the discovery of the etiologic agent (HIV) thereof in 1983 have led to the identification of an avalanche of anti-HIV compounds in which the Rega Institute has played a primordial role. Foremost among these compounds was tenofovir, discovered in collaboration with Antonín Holý from the IOCB (Institute of Organic Chemistry and Biochemistry) in Prague. Tenofovir laid the basis for the treatment of HIV (AIDS) and hepatitis B virus (HBV) infections, and in combination with emtricitabine it was the first chemical ever approved by the US FDA (Food and Drug Administration) for the prophylaxis of HIV infections.

Synthesis and Preliminary Antiviral Activities of Piperidine‐substituted Purines against <scp>HIV</scp> and Influenza A/H1N1 Infections

We have developed a series of N(2) -(1-(substituted-aryl)piperidin-4-yl)-N(6) -mesityl-9H-purine-2,6-diamine derivatives as potent antiviral agents. Preliminary biological evaluation indicated that nearly half of them possessed remarkable HIV inhibitory potencies in cellular assays. In particular, FZJ13 appeared to be the most notable one, which displayed anti-HIV-1 activity compared to 3TC. Moreover, an unexpected finding was that FZJ05 displayed significant potency against influenza A/H1N1 (strain A/PR/8/34) in Madin-Darby canine kidney cells with EC50 values much lower than those of ribavirin, amantadine, and rimantadine. The results suggest that these novel purine derivatives have the potential to be further developed as new therapeutic agents against HIV-1 or influenza virus.

Bicyclic Nucleoside Inhibitors of Varicella-Zoster Virus: 5′-Chloro and 3′-Chloro Derivatives

We have recently discovered bicyclic furopyrimidines as potent and selective inhibitors of VZV. In order to investigate the structural requirements for antiviral activity we have succesfully synthesised some 3'-chloro and 5'-chloro derivatives. The compounds have been tested against VZV and CMV, but displayed no significant in vitro activity.

Structure–activity relationships for dipeptide prodrugs of acyclovir: Implications for prodrug design

Inclination angle control for optimal tool orientation in 5-axis milling based on faceted models