bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Azolylalkyloxy Compounds with Antipicornaviral Activity
Authors: Abel M. D. , Cameron A. D. , Ha C. M. , Koski C. A. , Luu H. T. , Micetich R. G. , Nguyen D. Q. , Tempest M. L. , Daneshtalab M.
Published: May 2015

A novel series of azolylalkyloxy compounds was designed, synthesized and evaluated for antipicornaviral activity. Several of the compounds exhibited in vitro activity comparable to that of Disoxarll. An investigation of qualitative structure-activity relationships indicated that the optimal length of the alkyI chain is six or seven carbon atoms, with seven being marginally superior. The effect of different azole moieties on activity was relatively small, with 3-methylisoxazole and 4-methylthiazole being most effective. The nature of the oxy substituent was found to be extremely important for antipicornaviral activity. The 2-dibenzofuryl group proved to be the most effective oxy substituent for this class of compounds. Compounds 11 and 22, combining dibenzofuran with 3-methylisoxazole and 4-methylthiazole, respectively, were highly effective in vitro against a wide range of human rhinoviruses as well as several enteroviruses.
The Effect of Absolute Configuration on the Anti-HIV and Anti-HBV Activity of Nucleoside Analogues
Authors: Furman P. A. , Wilson J. E. , Reardon J. E. , Painter G. R.
Published: May 2015

This review concerns the effect of stereoisomerism on the selective activity of anti-HIV and anti-HBV nucleoside analogues.

The synthesis of a number of nucleoside analogues with anti-HIV and anti-HBV activity yields mixtures of 1-β-D and 1-β-L stereoisomers. Anti-HIV and anti-HBV activity is associated primarily with one of the two enantiomers and the more potent activity does not always reside with the 1-β-D configuration characteristic of natural nucleosides. In the case of HIV, the origin of this stereoselectivity appears to be the result of differential metabolism of the analogues and not due to differential inhibition of the target enzyme; the HIV reverse transcriptase. However, mutations at position 184 of the HIV-RT does result in stereoselective inhibition of the enzyme. On the other hand, with HBV, there is also a stereoselective inhibition of the HBV DNA polymerase, where the 5′-triphosphate of the 1-β-L enantiomer is the more potent inhibitor.
Herpesviruses as Co-Factors of HIV Disease: Case not Proven
Authors: Jeffries D. J.
Published: May 2015

Factors other than human immunodeficiency virus (HIV) may be important in determining disease progression in AIDS. The concept that viruses may act as co-factors in HIV pathogenesis has been based on in vitro studies of potential molecular or biological interactions between HIV and other viruses, some epidemiological evidence for an adverse effect of cytomegalovirus on progression to AIDS, and the apparent survival advantage conferred by aciclovir prophylaxis in people with AIDS.

It is possible that molecular or cellular interaction between herpesviruses or other infectious agents and HIV are necessary to encourage the virus into maximal production or to amplify pre-existing replication. However, there is no evidence as yet that this occurs, and studies that claim to show such an effect cannot be convincing unless they take account of the significant associations of progression with virus phenotype, host response, age and genetic factors.

This paper was presented as the case against in a debate on ‘Herpesviruses as co-factors of HIV disease’. The case for was made by Paul Griffiths (see page 17)
Pharmacokinetics of (-)-β-D-2,6-Diaminopurine Dioxolane and its Metabolite, Dioxolane Guanosine, in Woodchucks (Marmota Monax)
Authors: Rajagopalan Prabhu , Boudinot F. D. , Chu Chung K. , Tennant B. C. , Baldwin B. H. , Schinazi R. F.
Published: May 2015

The woodchuck ( Marmota monax) is a useful animal model for evaluating the in-vivo efficacy of antiviral agents against hepatitis B viral infection (HBV). The pharmacokinetics of a newly synthesized antiviral agent (-)-β-D-2,6-diaminopurine dioxolane (DAPD) in woodchucks is reported. DAPD is a nucleoside analogue, having potent and selective activity against human immunodeficiency virus and HBV in vitro. DAPD is susceptible to deamination in vivo by the ubiquitously present enzyme adenosine deaminase yielding the active metabolite dioxolane guanosine (DXG). The pharmacokinetics of DAPD and DXG were characterized following intravenous (i.v.) and oral (p.o.) administration of 20 mg kg−1 of DAPD to woodchucks. Plasma and urine samples were collected, and nucleoside concentrations were determined by HPLC. Following intravenous administration, the half-life of DAPD averaged 6.7 ± 4.3 h, and that of DXG averaged 17.6 ± 14.5 h. The mean total clearance and steady state volume of distribution of DAPD were 0.33 ± 0.14 L h kg−1 and 1.76 ± 0.65 L kg−1, respectively. The oral bioavailability of DAPD ranged from 3.7-8.2%; however, the apparent availability of DXG following oral administration of DAPD was 10.5-53%.
Properties and Anti-Hiv Activity of Hairpin Antisense Oligonucleotides Containing 2′-Methoxynucleosides with Base-Pairing in the Stem Region at the 3′-End
Authors: Hosono K. , Kuwasaki T. , Inagawa T. , Takai K. , Nakashima H. , Saito T. , Yamamoto N. , Takaku H.
Published: May 2015

A new type of hairpin antisense oligodeoxyribo-nucleotide, containing 2′-methoxynucleosides with base-pairing in the stem region at the 3′-end, was tested for 3′-exonuclease resistance and anti-HIV activity. An increased resistance to nuclease degradation has been observed by incubation of the hairpin oligo-nucleotides with DNA polymerase and foetal bovine serum. Of particular interest is the hairpin antisense oligonucleotide containing 2′-methoxynucleosides with base-pairing in the stem region at the 3′-end, which has increased nuclease resistance and hybridizes effectively with a complementary RNA. Furthermore, these compounds were assayed for inhibition of virus replication in HIV-1 infected MT-4 cells. In the anti-HIV activity test, the hairpin oligonucleotide phosphorothioate derivatives showed higher anti-HIV activities compared to their linear counterparts.
Synthesis of Mimics to 5-(2″-thienyl)-2′,3′-β-Dideoxyuridine Triphosphate
Authors: Persson T. , Hörnfeldt A.-B. , Gronowitz S. , Johansson N.G.
Published: May 2015

A series of 5′-amido derivatives of 5-(2″-thienyl)-2′,3′,5′-β-trideoxyuridine were prepared. The compounds were tested for their inhibition of cellular DNA polymerase α and α HIV-RT. The succinic fumaric and maleic acid derivatives of 5-(2″-thienyl)-2′,3′,5′-β-trideoxyuridine were investigated. None of the compounds inhibited HIV-RT. The fumaric acid derivative inhibited DNA pol α with IC50 33 μg ml−1. The succinic acid derivative was about half as active with IC50 76 μg ml−1. The 5′-N-acyl derivatives also were structurally compared to the monomethyl ester of the triphosphate using the Sybyl program.
Further Characterization of the Potent and Prolonged Inhibition of Herpes Simplex Virus Replication in Human Cell Lines by Penciclovir
Authors: Bacon T.H. , Howard B.A.
Published: May 2015

The replication of herpes simplex virus type 1 (HSV-1) or HSV-2 in MRC-5 cells infected at 0.01 pfu cell−1 treated continuously for 72 h, was inhibited more efficiently by penciclovir than aciclovir ( p = 0.0001). However, multiple cycles of replication were required in order to distinguish the compounds. Virus from cultures treated for 72 h with either compound, at 3 or 10 μg ml−1 was resistant to penciclovir and aciclovir (50% effective concentrations > 10 μg ml−1), but infectivity titres of supernatants from these aciclovirtreated cultures were higher than for penciclovir. Increased production of resistant virus in aciclovirtreated cultures may be the consequence of the less potent inhibition of virus replication by aciclovir. Penciclovir caused prolonged inhibition of HSV-1 and HSV-2 replication in three human cell lines infected at 1 pfu cell−1 following treatment for 18 h, whereas virus replication resumed rapidly after withdrawal of aciclovir. Neither compound showed prolonged activity after 18 h treatment, when the multiplicity of infection was reduced to 0.01 pfu cell−1. This surprising observation prompted experiments testing the effect of repeated pulse treatment in cultures infected at low multiplicity. Penciclovir inhibited HSV-1 replication significantly more effectively than aciclovir in MRC-5 cells infected at 10−4 pfu cell−1 treated daily for 6 h ( p < 0.001, n = 5) but only a trend was observed for HSV-2 ( p = 0.06, n = 6).
Anti-HCMV Activity of Cidofovir in Combination with Antiviral Compounds and Immunosuppressive Agents: In-Vitro Analyses
Authors: Mulato A. S. , Cherrington J. M. , Chen M. S.
Published: May 2015

Cidofovir 1-[(S)-3-hydroxy-2-(phosphonomethoxy) propyl] cytosine, HPMPC] is an acyclic cytosine nucleotide analogue with potent in-vitro and in-vivo activity against a broad spectrum of herpesviruses including human cytomegalovirus (HCMV). Cidofovir has recently been shown to delay the progression of HCMV retinitis in AIDS patients. Therefore, the effects of several antiviral compounds (GCV, AZT, ddC., ddl, d4T, 3TC and PMEA) on the anti-HCMV activity of cidofovir were investigated in vitro. Cidofovir in combination with GCV demonstrated synergistic inhibition of HCMV replication. Very little significant antiviral synergy or antagonism was measured for any of the other combinations. Furthermore, none of the combinations showed increased cytotoxicity in comparison with each drug alone. Additionally, the antiviral activity of cidofovir was determined in the presence of several immunosuppressive agents (hydrocortisone, cyclosporine A, methotrexate and mycophenolic acid) that are commonly used in the management of organ transplantation rejection in transplant patients. None of these agents altered the antiviral activity of cidofovir in vitro.
The FIAU Derivative (2′S)-2′-Deoxy-2′-C-Methyl-5-Iodouridine (SMIU) is a Novel, Less Cytotoxic and Potent anti-HSV and anti-VZV Agent
Authors: Kira T. , Awano H. , Shuto S. , Matsuda A. , Baba M. , Konno K. , Shigeta S.
Published: May 2015

In this study, the anti-herpetic activities of novel 2′-methyl nucleoside analogues which were substituted at the 5 position of the pyrimidine with a halogen were investigated. The 2′-fluoro-5-iodo-aracytosine (FIAC) congeners (2′S)-2′-deoxy-2′- C-methylcytidine which were substituted with Br or I at the 5 position (SMBC or SMIC); and 2′-fluoro-5-iodo-arauridine (FIAU) congeners (2′S)-2′-deoxy-2′-C-methyluridine which were substituted with Br or I at the 5 position (SMBU or SMIU), proved to have potent antiviral activities against herpes simplex virus type-1 (HSV-1) and varicella-zoster virus (VZV) but not against herpes simplex virus type-2 (HSV-2). SMIU has a higher selective index against HSV-1 than FIAU, and both SMIC and SMIU showed higher inhibitory effects against VZV replication than aciclovir. The four effective compounds were not inhibitory to a thymidine kinase (TK)-negative HSV-1 strain, and this result indicates that phosphorylation of the compounds by HSV or VZV-TK is necessary for the activation of these compounds.
Synergistic Inhibition of HIV-1 Reverse Transcriptase and HIV-1 Replication by Combining Trovirdine with AZT, ddl and ddC in Vitro
Authors: Zhang H. , Vrang L. , Rydergård C. , Åhgren C. , Öberg B.
Published: May 2015

Trovirdine (LY300046·HCI) is a potent and selective non-nucleoside human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) inhibitor (Åhgren et al., Antimicrob Ag Chemother 39: 1329, 1995). Combinations of trovirdine with other RT inhibitors, AZT, ddC., ddl and their triphosphates, were studied as well as the pyrophosphate analogue PFA in both cell-free HIV-1 polymerase assays and HIV-1-infected MT-4 cell cultures. Synergistic effects and weak synergism were observed both using RT and HIV-1 - infected cells and using different HIV-1 RT mutants and HIV-1 drug-resistant variants known to be resistant to the inhibitory effects of trovirdine. The best combination with substantial synergism was ddC-TP and trovirdine at a 20:1 molar ratio combination in a cell-free enzyme assay. This combination showed the weak synergy in MT-4 cells. Synergism was judged by the median-effect method. The inhibitory effect of trovirdine was independent of increased concentrations of AZT triphosphate and ddC triphosphate implying that trovirdine acts in a mutually exclusive manner with AZT-TP and ddC-TP as determined by the Dixon plot. The combination effects were expressed by the combination index (Cl) using end points of 50%, 70% and 90% inhibition of HIV-1 RT activity and HIV-1 replication in MT-4 cells.
4′-Thio-5-Ethyl-2′-Deoxyuridine5′-Triphosphate (TEDUTP): Synthesis and Substrate Properties in DNA-Synthesizing Systems
Authors: Alexandrova L.A. , Semizarov D.G. , Krayevsky A.A. , Walker R.T.
Published: May 2015

An efficient synthesis of the 5′-phosphate and 5′-triphosphate of a 4′-thio-2′-deoxynucleoside is described for the first time. The 5′-triphosphate of the antiherpesvirus agent 4′-thio-5-ethyl-2′-deoxyuridine (TEDU) has been shown to be a good substrate for human placental DNA polymerase α, calf thymus terminal deoxynucleotidyl transferase, and the reverse transcriptases of human immunodeficiency virus and avian myeloblastosis virus. As it is known that TEDU is a substrate only for herpesvirus-encoded thymidine kinases and not the cellular kinases, it is likely that the utilization of TEDUTP by DNA-synthesizing enzymes results in the selective toxicity seen in vitro in herpesvirus-infected cells.
Anti-HIV Activity of MDL 74968, a Novel Acyclonucleotide Derivative of Guanine: Drug Resistance and Drug Combination Effects in Vitro
Authors: Taylor D.L. , Ahmed S.P. , Brennan T.M. , Navé J.-F. , Casara P. , Tyms A.S.
Published: May 2015

MDL 74968 (9-[2-methylidene-3-(phosphonomethoxy)-propyl]guanine), a novel acyclonucleotide derivative of guanine, inhibited human immunodeficiency virus type 1 (HIV-1) replication in vitro with activity comparable to that of adefovir (PMEA; 9-(2-phosphonomethoxyethyl)adenine). MDL 74968 was investigated in combination with two licensed nucleoside analogues, zidovudine and didanosine, using a cell viability assay, and drug interactions were evaluated by the isobologram technique, by calculating combination indices and by the MacSynergy™ program. Inhibition of HIV-1 replication was only additive in both cases. MDL 74968 had equivalent antiviral activity against strains of HIV-1 HXB2 engineered to have mutations which conferred resistance to the nucleoside analogues lamivudine, didanosine and zidovudine and the non-nucleoside inhibitor of reverse transcriptase (RT) nevirapine, as against the wild type strain. Continued passage of HIV-1 RF in C8166 cells in the presence of MDL 74968 for 5 months (30 passages) failed to select drug resistant mutants. Continued passage of virus in the presence of the same concentration of adefovir for the same length of time selected a virus in a single culture, which was 3-fold resistant to adefovir and cross-resistant to MDL 74968. Genotypic characterization of this virus revealed a lysine to arginine exchange (AAA to AGA) at position 65 in the RT gene. This virus was not cross-resistant to either zidovudine or nevirapine but showed reduced sensitivity to zalcitabine, didanosine and lamivudine. Continued passage of HIV-1 RF in the presence of nevirapine or zidovudine, using similar experimental protocols selected drug resistant viruses after eight and 17 passages, respectively, but these viruses remained sensitive to adefovir and MDL 74968.
Virus Proteinase Inhibitors — What Next after HIV?
Authors: Mills J. S.
Published: May 2015

The recent approval by the regulatory authorities in the United States of several HIV proteinase inhibitors as therapeutics for the treatment of AIDS confirms that virus proteinases are valid molecular targets in the search for new antiviral drugs. This review summarizes the available approaches that can be taken to discover virus proteinase inhibitors and reviews the current status of our knowledge with respect to virus proteinases in viruses of clinical significance other than HIV. The major focus is on proteinases identified in the viruses that cause the common cold, hepatitis C virus and the herpesviruses.
Modulation of the Antiviral 2-5A System in Human Immunodeficiency Virus-1-Infected CEM Cells by Propentofylline
Authors: Leuck J. , Kuusksalu A. , Kelve M. , Vlassov V. , Müller W.E.G. , Schröder H.C.
Published: May 2015

2′,5′-OIigoadenylates (2-5A) play an essential role in the establishment of the antiviral state of cells exposed to virus infection. However, - after an initial increase observed in some cell lines - the activity of the interferon (IFN)-inducible, 2-5A-forming 2′,5′-oligoadenylate synthetase (2-5A synthetase) strongly decreases soon after infection of cells with the human immunodeficiency virus-1 (HIV-1). In the present report, we show that in IFN-treated human T lymphoblastoid CEM cells, the decrease in 2-5A synthetase activity had already occurred at day 1 post infection (p.i.)- At days 3 and 5 p.i., the 2-5A synthetase activity in the IFN-treated infected cells amounted to only 10-12% of that in IFN-treated uninfected control cells. The decrease in 2-5A synthetase activity was accompanied by a decrease in 2-5A synthetase mRNA and protein. We found that the decrease in 2-5A synthetase activity can be retarded by addition of the cAMP phosphodiesterase inhibitor, propentofylline. At a concentration of 30-100 μM, propentofylline displayed a significant cytoprotective and antiviral effect on HIV-1-infected CEM cells.
In-vitro anti Myxovirus Activity and Mechanism of Antiinfluenzavirus Activity of Polyoxometalates PM-504 and PM-523
Authors: Shigeta S. , Mori S. , Watanabe J. , Yamase T. , Schinazi R. F.
Published: May 2015

Sixty polyoxometalates were examined for anti-influenza A virus (FluV-A) activity in vitro. Two of the most potent and least cytotoxic compounds, PM-504 K9H5(Ge2Ti6W18O77)16H2O] and PM-523 (iPrNH3)6H [PTi2W10O38(O2)9H2O2] were selected for further studies. Examination of the antiviral effects of PM-504 and PM-523 against other human ortho- and paramyxoviruses revealed that both compounds had broad spectrum antimyxovirus activities. From a time of addition study and FACS analysis for influenza A virus infected cells, the compounds were found not to inhibit binding of virus to MDCK cells. However, these compounds inhibited haemolysis of chicken erythrocytes by virus and also inhibited fluorescence dequenching of octadecylrhodamine B-labelled virus after binding to cells. This indicates that these polyoxometalates inhibited fusion of the virus envelope to the cellular membrane.
Identification of N-Hydroxamic Acid and N-Hydroxyimide Compounds that Inhibit the Influenza Virus Polymerase
Authors: Cianci C. , Chung T.D.Y. , Meanwell N. , Putz H. , Hagen M. , Colonno R. J. , Krystal M.
Published: May 2015

The RNA-dependent RNA polymerase of influenza virus transcribes messenger RNA through a unique cap-scavenging mechanism. The polymerase binds to the cap structure at the 5′ ends of host mRNAs, which are then cleaved and used as primers for viral mRNA synthesis. In an effort to discover antiviral compounds against this target, an in-vitro transcription assay was utilized to screen a proprietary chemical collection. Results of this screening effort identified an N-hydroxamic acid structure as an inhibitor of the capped RNA-dependent transcriptase activity. Subsequent sub-structure searching and screening based upon this pharmacophore identified two related N-hydroxyimide compounds as specific inhibitors. These compounds were found to inhibit the cap-scavenging mechanism through inhibition of the endonuclease function of the polymerase.
HPMPC (cidofovir), PMEA (adefovir) and Related Acyclic Nucleoside Phosphonate Analogues: A Review of their Pharmacology and Clinical Potential in the Treatment of Viral Infections
Authors: Naesens L , Snoeck R , Andrei G , Balzarini J , Neyts J , De Clercq E
Published: May 2015

The acyclic nucleoside phosphonate (ANP) analogues are broad-spectrum antiviral agents, with potent and selective antiviral activity in vitro and in vivo. The prototype compounds are: ( S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC, cidofovir), which is active against a wide variety of DNA viruses; 9-(2-phosphonylmethoxyethyl)adenine (PMEA, adefovir), which is active against retro-, herpes- and hepadnaviruses, and ( R)-9-(2-phosphonylmethoxypropyl) adenine (PMPA), which is active against retro- and hepadnaviruses. The antiviral action of the ANP analogues is based on a specific interaction of the active diphosphorylated metabolite with the viral DNA polymerase. The long intracellular half-life of the active metabolite accounts for the optimal efficacy in infrequent dosing schedules. The potential of HPMPC as a broad-spectrum anti-DNA virus agent, as originally observed in vitro and in vivo, has been confirmed in clinical trials. HPMPC has recently been commercially released in the USA for the treatment of cytomegalovirus retinitis in AIDS patients. In addition, topical systemic HPMPC is being (or will be) explored for use against other herpesviruses (i.e. herpes simplex virus, Epstein-Barr virus, or varicella-zoster virus), by adenoviruses, or by human papilloma- or polyomaviruses. Intravenous HPMPC is associated with dose-dependent nephrotoxicity, that should be counteracted by prehydration and concomitant administration of probenecid, and by the application of an infrequent dosing schedule. The oral prodrug of PMEA, bis(pivaloyloxymethyl)-PMEA, is currently being evaluated in patients infected with human immunodeficiency virus (HIV) or hepatitis B virus. Finally, preclinical data on the efficacy of PMPA in animal retrovirus models point to its potential usefulness against HIV infections, when given either prophylactically or therapeutically in the treatment of established HIV infections.
Selective Activity of Various Nucleoside and Nucleotide Analogues against Human Herpesvirus 6 and 7
Authors: Takahashi K , Suzuki M , Iwata Y , Shigeta S , Yamanishi K , De Clercq E
Published: May 2015

We have developed a new sensitive enzyme immunoassay (EIA) and MTT (tetrazolium salt) assay for screening compounds against two variants of human herpesvirus 6 (HHV-6A, HHV-6B) and human herpesvirus 7 (HHV-7) and evaluated the anti-HHV-6 and HHV-7 activity of a series of anti-herpesvirus compounds and acyclic nucleoside phosphonate analogues. The results indicate that the pattern of activity of these compounds against these betaherpesviruses is similar to that for human cytomegalovirus (HCMV). The highest potency and selectivity against the two variants of HHV-6 and HHV-7 was demonstrated by S2242 (N7-isomer of 6-deoxy-ganciclovir). Also, ganciclovir (GCV), foscarnet, (phosphonoformic acid; PFA) and the acyclic nucleoside phosphonate analogues such as cidofovir (HPMPC) exhibited selective inhibitory activity against these viruses. Thymidine kinase (TK)-dependent drugs (acyclovir, ACV; brivudin, BVDU; and sorivudine, BVaraU) showed little, if any, activity. These results suggest a structural homology of the DNA polymerase and a lack of TK gene among these three betaherpesviruses (HHV-6, HHV-7 and HCMV). The finding that HHV-7 was highly sensitive to GCV also suggests that HHV-7 may have an HCMV-UL97-homologue gene for the phosphorylation of GCV. The present EIA method is more rapid and sensitive than the previously reported procedures and could be useful for the large-scale screening of compounds against HHV-6 and HHV-7.
Inhibitory Effect of Polyionic Compounds on the Adsorption of Herpes Simplex Virus Type 1 (KOS)
Authors: Yang Y-W , Yang J-C
Published: May 2015

The polyionic compounds, including dextran sulphates and poly-L-lysines, were evaluated for their inhibitory effect on the cytopathic effect of herpes simplex virus (HSV-1, KOS) in vitro. The anti-HSV activities of poly-L-lysines were found to increase with increasing molecular weight of the polymers. Both dextran sulphates and poly-L-lysines were found to block adsorption of HSV-1 to Vero cells. The inhibitory effect of adsorption of [3H] labelled virus was related to the molecular weight of the polymers. Polymers of higher molecular weight were found to be more effective than the lower molecular weight samples in inhibiting virus adsorption. The results from the microelectrophoresis measurements demonstrated that poly-L-lysines adsorb and confer positive charges on the Vero cells. Dextran sulphates, on the other hand, may adsorb onto the HSV-1 membrane surfaces instead of binding onto the cell membranes and interfere with adsorption of virions to the cells. The inhibitory effects of these polymers on viral cytopathogenic effect were probably attributable to the electrostatic and steric hindrance effects exerted by the polymers as reflected in the difference in zeta potential of cellular membrane treated with these compounds.
Distribution to the Brain and Protein Binding of 3′and 5-Substituted 2′,3′-Dideoxyuridine Derivatives, Studied by Microdialysis
Authors: Borg N , Zhou X-X , Johansson N-G , Öberg B , Ståhle L
Published: May 2015

The aim of this study was to investigate a series of 3′ and 5-substituted 2′,3′-dideoxyuridine derivatives (ddUD) with respect to plasma protein binding, half-life and distribution across the blood-brain barrier in the rat. The microdialysis technique was used to study protein binding in human plasma ( in vitro), and to sample the extracellular space of rats with microdialysis probes implanted into the striatum of the brain and the gastrocnemic muscle ( in vivo). The compounds were analysed by HPLC with UV-detection. The octanol/water partition coefficients of the ddUD varied from 0.08-0.84. The protein binding of the ddUDs was approximately 80%. After s.c. administration (25 or 50 mg kg−1), the brain and muscle extracellular levels differed; brain levels were 0.18-0.36 of peripheral (muscle) concentrations. A multivariate analysis, which included data on zidovudine, alovudine and thymidine, demonstrated a relationship between the physicochemical and some of the pharmacokinetic properties of uridine analogues. The analysis shows that half-life and protein binding increases with decreasing p Ka. However, penetration to the brain is not correlated with the partition into octanol. It is concluded that the transport to the brain is not primarily dependent upon passive diffusion over a lipophilic barrier but, rather, to other chemical properties of the ddUDs. This is suggestive of a specific transport mechanism, e.g. the thymidine carrier.
Incorporation of Selected Nucleoside Phosphonates and Anti-Human Immunodeficiency Virus Nucleotide Analogues into DNA by Human DNA Polymerases α, β and γ
Authors: Cihlar T , Chen MS
Published: May 2015

Incorporation of selected diphosphates of nucleoside phosphonates and triphosphates of currently approved anti-human immunodeficiency virus nucleoside analogues into DNA by human DNA polymerases α, β and γ was studied. All three polymerases were able to incorporate diphosphates of 9-(2-phosphonomethoxyethyl)adenine (PMEApp), 9-(2-phosphonomethoxyethyl)guanine (PMEGpp), ( R)-9-(2-phosphonomethoxypropyl)adenine (PMPApp), ( R)-9-(2-phosphononomethoxypropyl)-2,6-diaminopurine (PMPDAPpp) and ( 2R,5R)-9-[2,5-dihydro-5-(phosphonomethoxy)-2-furanyl]adenine (D4APpp) into primer/template DNA of defined sequence. After incorporation, these nucleoside phosphonates acted as terminators of primer extension. Kinetic constants of their incorporation were determined and compared with those for incorporation of ddATP, ddCTP, (-)-2′-deoxy-3′-thiacytidine triphosphate (3TC-TP), 2′,3′-didehydro-3′-deoxythymidine triphosphate (d4T-TP) and 3′-azido-3′-deoxythymidine triphosphate (AZT-TP). Relative efficiencies of incorporation (percentage of the incorporation efficiency for the corresponding natural deoxynucleoside triphosphate) by DNA polymerase a ranged from 0.05% for 3TC-TP to 51% for PMEGpp. DNA polymerase β catalysed the incorporation with relative efficiencies ranging from 0.014% for AZT-TP to 125% for ddCTP, and efficiencies of incorporation by DNA polymerase γ varied between 0.13% for 3TC-TP and 25% for ddCTP. Generally, the lowest incorporation efficiencies with all three polymerases were found for PMPApp (0.06–1.4%) and PMPDAPpp (0.075–2.2%).
Arylketotetramethylene Analogues of Disoxaril with Anti-Human Rhinovirus 14 Activity
Authors: Mai A , Artico M , Sbardella G , Massa S , De Montis A , Puddu I , Musiu C , La Colla P
Published: May 2015

Arylketotetramethylene analogues of disoxaril (WIN 51711) were synthesized by reaction of 1-aryl-5-chloropentan-1-ones with 2-(4-hydroxyphenyl)-4,5-dihydro oxazoles, ethyl 4-hydroxybenzoates and 4-hydroxybenzonitrile. The new derivatives were tested for antiviral activity against various human rhinovirus (HRV) serotypes. The best activity was exhibited by the ethoxycarbonyl derivatives, whereas the oxazoline counterparts were less active and the cyano derivatives totally inactive. 5-[4-(4,5-Dihydro-2-oxazolyl)phenoxy]-1-(4-methoxyphenyl)pentan-1-one and ethyl 4-[5-(4-methylthiophenyl)-5-oxopentoxy] benzoate were more active than, and as active as, disoxaril, respectively, against HRV-14. Moreover, they were 10 times less cytotoxic.
Development of a Continuous Fluorescence Assay for Rhinovirus 14 3C Protease Using Synthetic Peptides
Authors: Wang QM , Johnson RB , Cohen JD , Voy GT , Richardson JM , Jungheim LN
Published: May 2015

Rhinovirus 3C protease is an attractive target for therapeutic intervention owing to its important role in virion maturation and infectivity. In order to facilitate the identification of potential 3C protease inhibitors, we have developed a continuous fluorescence assay using 5-[(2-aminoethyl)amino]naphthalene-1-sulphonic acid (Edans) as a fluorescent donor and 4-(4-dimethylaminophenylazo)benzoic acid (Dabcyl) as a quenching acceptor. Several fluorogenic peptide substrates for 3C protease were synthesized by both solution chemistry and solid phase peptide synthesis. One of the synthetic Edans/Dabcyl substrates, with an amino acid sequence derived from the 2C/3A site of the virus polyprotein, yielded a 24-fold increase in fluorescence intensity after 3C cleavage. Data regarding substrate cleavage kinetics, assay sensitivity and optimization are presented. The application of this assay to the evaluation of 3C protease inhibitors is also shown.
The Herpesvirus Family in the 21st Century
Authors: Griffiths P
Published: May 2015

Eight members of the human herpesvirus (HHV) family have been discovered to date. All the viruses have a characteristic virion structure and share a number of other features. From the perspective of potential treatments, these include the encoding of a protease enzyme which is essential for virus assembly, a DNA polymerase and at least one kinase enzyme which can phosphorylate nucleosides. The herpesviruses also demonstrate a number of mechanisms for avoiding the host immune system, including interference with different stages of the presentation of viral peptides on the cell surface by class I human leukcocyte antigen (HLA) proteins. Three members of the herpesvirus family (HHV-6, HHV-7 and HHV-8) have been discovered within the last 10 years. Both HHV-6 and HHV-7 cause exonthem subitum, although HHV-7 seems to be less pathogenic than HHV-6. HHV-6 also appears to be associated with a number of other disorders. HHV-8 was discovered by the newly developed technique of representational difference analysis, and was identified in Kaposi's sarcoma (KS) tissue. Although the studies to date do not prove that HHV-8 causes KS, they show that the virus is closely associated with the disease. Since discovery of these HHV has been facilitated by the development of new techniques, further technological advances could help to uncover new members of the family.
The Value of Antivirals in Genital Herpes
Authors: Woolley P
Published: May 2015

Although aciclovir has been the most extensively used nucleoside analogue for the treatment of genital herpes, its poor bioavailability, frequent dosing (five times daily), and the short intracellular half-life of the active triphosphate (≤1–2 h) has led to the development of a new generation of agents. The prodrug valaciclovir (active agent aciclovir), and famciclovir (active agent penciclovir) have improved pharmacokinetics compared with aciclovir. Compared with oral aciclovir, valaciclovir yields aciclovir with three-fivefold higher serum levels and the oral prodrug famciclovir yields even higher serum levels of penciclovir. The active agent, penciclovir triphosphate, has a prolonged intracellular half-life in vitro [10 h for cells infected with herpes simplex virus type 1 (HSV-1) and 20 h for HSV-2-infected cells]. Evidence also suggests that famciclovir may have an effect on the establishment of latency in primary infection, thus reducing the risk of subsequent recurrent disease. Ongoing clinical trials are underway exploring this possibility. For patients with frequent recurrences of genital herpes, or patients psychologically disabled by the condition, twice-daily antiviral therapy offers the most effective reduction in the frequency of clinical recurrence. Twice-daily therapy also has the advantage that patients are at less risk of asymptomatic breakthrough and the potential risk of transmission if they forget to take one dose.
Can Herpes Simplex Virus Latency Be Prevented Using Conventional Nucleoside Analogue Chemotherapy?
Authors: Field HJ , Thackray AM
Published: May 2015

This review summarizes work that has been published recently in several papers reporting the effects of famciclovir and valaciclovir therapy on the establishment of herpes simplex virus (HSV) latency in a murine cutaneous infection model. For both HSV-1 and HSV-2 infections, therapy with famciclovir or valaciclovir from 1 or 2 days after virus inoculation reduced the ability to reactivate infectious virus from explanted ganglia when this was attempted several weeks after the primary infection. For famciclovir, the reduced ability to reactivate virus was also apparent in mice in which the onset of therapy was delayed for up to 3–5 days after virus inoculation. When more sensitive methods were employed to detect latency, all mice were found to be positive for latent infections in the ganglia, including those from mice receiving early therapy. However, for mice that had received oral famciclovir treatment the relative number of latently infected ganglion cells, as determined by infectious centres, appeared to be greatly reduced; this is thought to explain the failure to reactivate virus by means of the explant method. These results show a marked difference in activity between famciclovir and valaciclovir in this model and suggest that prompt therapy of first episode herpes by means of famciclovir may be able to reduce the establishment of latency in humans, where the establishment of latent infections in ganglionic neurons is thought to be a slower process than that observed in mice.
Combinations of Antiviral and Anti-Inflammatory Preparations for the Topical Treatment of Herpes Simplex Virus Assessed using a Murine Zosteriform Infection Model
Authors: Awan AR , Harmenberg J , Flink O , Field HJ
Published: May 2015

Recently we have reported a zosteriform murine infection model which employs the adoptive transfer of immune cells (ATI) to recipient infected mice to produce a disease that mimics human recurrent herpes simplex virus (HSV) disease. Mice were infected with HSV-1 by scarification at the lateroventral line of the neck; 2 days later, the mice received immune cells from HSV-1-infected syngeneic mice. Although virus was cleared more quickly from the target tissues of virus replication in recipient mice, ATI resulted in a heightened inflammatory response and delayed healing. This model was used to test the effects of topical formulations containing foscarnet and/or the anti-inflammatory agent, hydrocortisone. Virus clearance and clinical signs, including ear thickness and zosteriform spread of lesions, were studied. Treatment with 3% foscarnet accelerated virus clearance but had little effect on clinical parameters. By contrast, 0.5% hydrocortisone increased the titre and extended the presence of infectious virus for at least 6 days, although the reduction in clinical signs was greater than that obtained with topical foscarnet. Foscarnet in combination with hydrocortisone produced a marked reduction in clinical signs while virus replication was reduced. These results are discussed in relation to the inflammation and discomfort experienced by patients and a possible role for anti-inflammatory formulations in the treatment of HSV reactivation episodes in man.
Synthesis and Antiviral Evaluation of SATE-Foscarnet Prodrugs and New Foscarnet—AZT Conjugates
Authors: Meier C , Aubertin A-M , de Monte M , Faraj A , Sommadossi J-P , Périgaud C , Imbach J-L , Gosselin G
Published: May 2015

The synthesis of a range of di- and triester derivatives of phosphonoformate (PFA; foscarnet) as potential lipophilic, membrane-soluble prodrugs is described. In addition to normal alkyl esters in the carboxylate and phosphonate residues of PFA, the bioreversible S-(pivaloyl)thioethyl ( t-butyl-SATE) group was introduced in an attempt to deliver PFA after bioactivation inside the cells. Furthermore, PFA—AZT conjugates were prepared in order to develop combinational drugs. The key synthetic step was in all cases the formation of the P—C bond to build up the different PFA esters. In contrast to the diester derivatives, the triesters of PFA showed high hydrolytic instability during chromatographic purification. The compounds were evaluated in vitro for their ability to inhibit viruses in several tissue culture systems. All PFA alkyl di- and triesters proved poorly active or inactive against human immunodeficiency virus (HIV) and inactive against hepatitis B virus. In contrast, the PFA—AZT conjugates exhibited significant anti-HIV activity. However, this activity was nearly completely lost in thymidine kinase-deficient cells, suggesting a fast unselective chemical hydrolysis of the conjugates to yield the nucleoside analogue AZT in the cell culture medium. Furthermore, no synergistic effect of PFA and AZT was observed.
Approaches to Antiviral Chemotherapy for Acute Respiratory Infections
Authors: Shigeta Shiro
Published: May 2015

The causative agents of acute respiratory infections (ARI) in infants and children are mostly thought to be viruses. Some ARI in adult patients may be caused by bacteria but most often the causes are virus infections. When ARI affect immunocompromised patients or the elderly the mortality rates are significantly higher than in immunocompetent individuals. Many types of viruses cause ARI. Among them, influenza viruses A and B and respiratory syncytial virus (RSV) are thought to be the most important because of the severity of illness after infection and their high communicability in the human population. Recently, several novel antiviral drugs against ARI have been developed and some are proceeding in clinical trials. This review covers current investigations into antiviral compounds targeted at several points in the virus life-cycle. This includes PM-523, which broadly inhibits ortho- and paramyxoviruses, two neuraminidase inhibitors for influenza virus, neutralizing antibody to RSV and chimeric soluble ICAM-1–IgA molecules targeted against rhinoviruses.
1,2,5-Benzothiadiazepine and Pyrrolo[2,1-d]-[1,2,5]Benzothiadiazepine Derivatives with Specific Anti-Human Immunodeficiency Virus Type 1 Activity
Authors: Di Santo R , Costi R , Artico M , Massa S , Marongiu ME , Loi AG , De Montis A , La Colla P
Published: May 2015

We synthesized and tested as novel inhibitors of human immunodeficiency virus type 1 (HIV-1) bi- and tricyclic thiadiazine ring homologues of 7-chloro-2-ethyl-2 H-1,2,4-benzothiadiazin-3-(4 H)-one 1,1-dioxide, which is a compound endowed with anti-HIV-1 activity at low micromolar concentrations. Benzothiadiazepine derivatives were obtained by alkylation of 8-chloro-2,3-dihydro-3-methyl-1,2,5-benzothiadiazepin-4(5 H)-one 1,1-dioxide, which was obtained by intramolecular cyclization of 2-(2-amino-5-chloro-benzenesulphonamido) propanoic acid. Pyrrolobenzothiadiazepines were synthesized from N-substituted 5-chloro-2-(1 H-pyrrol-1-yl)benzenesulphonamides by treating with triphosgene. N6-substituted pyrrolo[2,1-d][1,2,5]benzothiadiazepin-7(6 H)-one 5,5-dioxides were active, thoughnot very potent. Both a chlorine atom and an unsaturated alkyl chain were found to be determinants of anti-HIV-1 activity. The highest potency was shown by a derivative with a TIBO-related 3,3-dimethylallyl chain. 2,3-Dihydro-1,2,5-benzothiadiazepin-4(5 H)-one 1,1-dioxides were scarcely active in HIV-1-infected MT-4 cell assays; however, the introduction of the dimethylallyl chain into 7-chloro-1,2,5-benzothiadiazepine moiety led to a bicyclic derivative which was more potent and less cytotoxic than the tricyclic pyrrole-containing counterpart.
Isolation and Characterization of the Fungal Metabolite 3-O-Methylviridicatin as an Inhibitor of Tumour Necrosis Factor α-Induced Human Immunodeficiency Virus Replication
Authors: Heguy A , Cai P , Meyn P , Houck D , Russo S , Michitsch R , Pearce C , Katz B , Bringmann G , Feineis D , Taylor DL , Tyms AS
Published: May 2015

The cytokine tumour necrosis factor α (TNF-α) has been shown to play a role in human immunodeficiency virus (HIV) replication by activating transcription of the provirus in both T cells and macrophages. Therefore, agents that block TNF-α-induced HIV expression could have therapeutic value in the treatment of AIDS. We have sought to identify antiviral agents that block TNF-α induction of HIV LTR-directed transcription, using a cell-based, virus-free assay system in automated high-throughput screening. HeLa cells were transfected with an HIV LTR–luciferase reporter plasmid and a stable line was isolated in which TNF-α increased luciferase production by two- to threefold. This cell line was used to screen approximately 15 000 fungal extracts. An inhibitory activity specific for TNF-α-induced HIV LTR transcription was observed in culture OS-F67406. The active component was isolated and identified as a known metabolite, 3-O-methylviridicatin, by NMR and mass spectrometry. No biological activity has been associated with this compound previously. This compound blocks TNF-α activation of the HIV LTR in the HeLa-based system, with an IC50 of 5 μM, and inhibited virus production in the OM-10.1 cell line, a model of chronic infection responsive to induction by TNF-α, with an IC50 of 2.5 μM.
Specific Inhibition of Influenza Virus RNA Polymerase and Nucleoprotein Gene Expression by Liposomally Encapsulated Antisense Phosphorothioate Oligonucleotides in MDCK Cells
Authors: Abe T , Suzuki S , Hatta T , Takai K , Yokota T , Takaku H
Published: May 2015

We have demonstrated that antisense phosphorothioate oligonucleotides (S-ODNs) inhibit influenza A virus replication in MDCK cells. Liposomally encapsulated and free antisense S-ODNs with four target sites (PB1, PB2, PA and NP genes) were tested for their abilities to inhibit virus-induced cytopathogenic effects in a MTT assay using MDCK cells. The liposomally encapsulated S-ODN complementary to the site around the PB2 AUG initiation codon showed highly inhibitory effects. In contrast, the inhibitory effect of the liposomally encapsulated S-ODN targeted to PB1 was considerably decreased in comparison with that directed to the PB2 target site. The liposomally encapsulated antisense S-ODNs exhibited higher inhibitory activities than the free oligonucleotides, and showed sequence-specific inhibition, whereas free antisense S-ODNs were observed to inhibit viral adsorption to MDCK cells. Liposomal preparations of oligonucleotides facilitated their release from endocytic vesicles, and thus cytoplasmic and nuclear localization was observed. The activities of the antisense S-ODNs were effectively enhanced by using the liposomal carrier. Interestingly, the liposomally encapsulated FITC-S-ODN-PB2–as accumulated in the nuclear region of MDCK cells. However, weak fluorescence was observed within the endosomes and the cytoplasm of MDCK cells treated with the free antisense S-ODNs. The cationic lipid particles may thus be a potentially useful delivery vehicle for oligonucleotide-based therapeutics and transgenes, appropriate for use in vitro or in vivo.
Novel 3′-Spiro Nucleoside Analogues of TSAO-T. Part II. a Comparative Study Based on NMR Conformational Analysis in Solution and Theoretical Calculations
Authors: Alvarez R , Jimeno M-L , Gago F , Balzarini J , Pérez-Pérez M-J , Camarasa M-J
Published: May 2015

The structures of two novel 3′-spiro nucleosides analogues of the potent human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) inhibitor TSAO-m3T, in solution, as derived from NMR spectroscopy are described. In these TSAO analogues the spiro amino oxathioledioxide moiety has been replaced by spiro amino oxazolone or spiro amino oxathiazoledioxide moieties. A comparative study based on theoretical calculations of the hydrophobicity, the solvation free energies and molecular electrostatic potentials (MEP) of the three compounds is also described. No significant conformational differences were detected in solution between TSAO-m3T and its analogues that might account for the differencesobserved in their inhibitory activity against HIV-1 RT. The calculated hydrophobicity (log P) values, dipole moments and the electrostatic contributions to the solvation free energies of the three spiro ring systems were also similar. However, the differences found in the calculated MEPs of the spiro systems between TSAO-m3T and its analogues suggest that the different electrostatic surroundings of the 4″-amino group of the spiro moiety in the analogues may be responsible for a detrimental electrostatic interaction of the spiro rings with the Glu-B138 of RT.
Creating a film poem with stylistic analysis: A pedagogical approach
Authors: O’Halloran Kieran
Published: May 2015

A film poem is a cinematic artwork that takes a written, often canonical, poem as its stimulus. Many are imaginative and arresting performances of poems, going far beyond the likely intentions of the poet into something completely new. However, with this genre, the poem’s stylistic detail is largely irrelevant to its visual realisation. I highlight how this limitation can be addressed by bringing film poems into stylistics teaching and assessment. After providing background on the film poem genre, I model an assignment where students draw on their cinematic literacy to dramatise a poem imaginatively. As with other film poems, the student creates a series of cinematic images and connects them to the poem’s lines, activating new meanings in them. In contrast with the traditional construction of film poems, the procedure involves another stage – the student also connects the images they have created to the poem’s stylistic detail. In turn, as I show, this extra connection helps drive the film’s narrative, adding to the creativity of the film. This staged procedure is different from established (pedagogical) stylistic practice where interpretation and stylistic analysis of a poem are simultaneous, with the stylistic analysis providing support for the burgeoning interpretation. To model this student assignment, I produce a film script of Philip Larkin’s poem, ‘Wants’. The script depicts the activities of a serial killer; some readers may find the script graphic.