-
Journal of Virology Feb 1987An aphidicolin-resistant (Aphr) mutant of herpes simplex virus (HSV) type 2 strain 186 previously has been shown to induce an altered viral DNA polymerase that is more...
An aphidicolin-resistant (Aphr) mutant of herpes simplex virus (HSV) type 2 strain 186 previously has been shown to induce an altered viral DNA polymerase that is more resistant to aphidicolin and more sensitive to phosphonoacetic acid (PAA) than is wild-type DNA polymerase. In this study the mutation responsible for the aphidicolin-resistant phenotype was physically mapped by marker transfer experiments. The physical map limits for the Aphr mutation were contained in a 1.1-kilobase pair region within the HSV DNA polymerase locus. The 1.1-kilobase-pair fragment of the Aphr mutant also conferred hypersensitivity to PAA, and DNA sequence analysis revealed an AT to GC transition within this fragment of the Aphr mutant. Analysis of the three potential open reading frames within the 1,147-base-pair fragment and comparison with the amino acid sequence of DNA polymerase of HSV type 1 indicated that the Aphr mutant polymerase had an amino acid substitution from a tyrosine to a histidine in the well-conserved region of the DNA polymerase. These results indicate that this single amino acid change can confer altered sensitivity to aphidicolin and PAA and suggest that this region may form a domain that contains the binding sites for substrates, PPi, and aphidicolin.
Topics: Animals; Aphidicolin; Base Sequence; Cell Line; DNA-Directed DNA Polymerase; Diterpenes; Drug Resistance, Microbial; Genes; Genes, Viral; Mutation; Phenotype; Phosphonoacetic Acid; Simplexvirus
PubMed: 3027369
DOI: 10.1128/JVI.61.2.388-394.1987 -
Antimicrobial Agents and Chemotherapy Feb 1998The pharmacokinetics, absolute bioavailability, accumulation, and tolerability over 8 days of an oral formulation of foscarnet (90 mg/kg of body weight once daily [QD]...
The pharmacokinetics, absolute bioavailability, accumulation, and tolerability over 8 days of an oral formulation of foscarnet (90 mg/kg of body weight once daily [QD] [n = 6], 90 mg/kg twice daily [BID] [n = 6], and 180 mg/kg QD [n = 31) were investigated in 15 asymptomatic, human immunodeficiency virus-seropositive male patients free of active cytomegalovirus infection and with normal upper gastrointestinal function. Peak plasma drug concentrations were (mean +/- standard deviation) 46.4 +/- 10.8 microM (90 mg/kg QD), 45.7 +/- 6.9 microM (90 mg/ kg BID), and 64.9 +/- 31.7 microM (180 mg/kg QD) on day 1 and rose to 86.2 +/- 35.8, 78.7 +/- 35.2, and 86.4 +/- 25.0 microM, respectively, on day 8. The mean peak concentration in plasma following the intravenous administration of foscarnet (90 mg/kg) was 887.3 +/- 102.7 microM (n = 13). The terminal half-life in plasma remained unchanged, averaging 5.5 +/- 2.2 h on day 1 (n = 15) and 6.6 +/- 1.9 h on day 8 (n = 13), whereas it was 5.7 +/- 0.7 h following intravenous dosing. Oral bioavailabilities were 9.1% +/- 2.2% (90 mg/kg QD), 9.5% +/- 1.7% (90 mg/kg BID), and 7.6% +/- 3.7% (180 mg/kg QD); the accumulation ratios on the 8th day of dosing were 2.1 +/- 1.1, 1.8 +/- 0.4, and 1.7 +/- 0.7, respectively. The overall 24-h urinary excretion of oral foscarnet averaged 7.8% +/- 2.6% (day 1) and 13.4% +/- 6.0% (day 8), whereas it was 95.0% +/- 4.9% after intravenous dosing. The glomerular filtration rate and creatinine clearance remained constant, and the mean 24-h renal clearances of foscarnet for the entire study group were 96 +/- 18 ml/min (day 1), 88 +/- 13 ml/min (day 8), and 103 +/- 16 ml/min after intravenous dosing. Adverse effects were largely confined to gastrointestinal disturbances, with all subjects experiencing diarrhea that was dose dependent in its severity. The results suggest that the formulation studied would require significant improvement with respect to tolerability and bioavailability to gain clinical acceptance.
Topics: Administration, Oral; Adult; Antiviral Agents; Biological Availability; Foscarnet; HIV; HIV Infections; HIV Seropositivity; Humans; Male; Middle Aged; Xylose
PubMed: 9527775
DOI: 10.1128/AAC.42.2.293 -
Virology Jun 2000Pyrazofurin (PZF), a cytidine analog and an inhibitor of orotate monophosphate decarboxylase, has been shown to decrease the levels of UTP and CTP in treated cells. When...
Pyrazofurin (PZF), a cytidine analog and an inhibitor of orotate monophosphate decarboxylase, has been shown to decrease the levels of UTP and CTP in treated cells. When Sindbis virus (SV)-infected Aedes albopictus cells were treated with PZF, the yield of virus was reduced 100- to 1000-fold. By serial passage of our standard SV(STD) in Ae. albopictus cells in the presence of increasing concentrations of PZF, a mutant, SV(PZF), was derived, which was not inhibited by PZF. SV(PZF) is also resistant to adenosine, guanosine, and phosphono-acetyl-N-aspartate, all of which have been shown to decrease levels of UTP and CTP. Analysis of chimeric viruses containing sequences from the SV(PZF) and parental genomes showed that the sequence between nt 5262 and 7999 conferred the PZF-resistant phenotype. Sequencing of this region identified four mutations (nt 5750, 6627, 7543, and 7593), which are predicted to lead to amino acid changes: opal550L in nsP3 and M287L, K592I, and P609T in nsP4. Characterization of viruses containing one or more of these mutations demonstrated that all three mutations in the nsP4 coding region are required to produce full resistance to PZF. Using a molecular model of nsP4 based on the structure of HIV reverse transcriptase, we located amino acid change M287L at the tip of the fingers domain and K592I and P609T at the base of the thumb domain of the viral RNA polymerase. We suggest that these three amino acid changes in nsP4 alter the geometry of the NTP binding pocket so as to increase the affinity of the enzyme for CTP and UTP.
Topics: Adenosine; Aedes; Amides; Amino Acid Substitution; Animals; Aspartic Acid; Binding Sites; Cells, Cultured; Chick Embryo; DNA-Directed RNA Polymerases; Dose-Response Relationship, Drug; Drug Resistance, Microbial; Fibroblasts; Guanosine; Models, Molecular; Mutation; Phenotype; Phosphonoacetic Acid; Protein Structure, Tertiary; Pyrazoles; Recombination, Genetic; Ribonucleosides; Ribose; Sindbis Virus; Virus Replication
PubMed: 10873749
DOI: 10.1006/viro.2000.0329 -
Dental Materials Journal 2011The effect of metal primers on adhesion of a resin composite to dental metal alloys was investigated. Experimental primers containing a dithiooctanoate monomer... (Comparative Study)
Comparative Study
Design of a metal primer containing a dithiooctanoate monomer and a phosphonic acid monomer for bonding of prosthetic light-curing resin composite to gold, dental precious and non-precious metal alloys.
The effect of metal primers on adhesion of a resin composite to dental metal alloys was investigated. Experimental primers containing a dithiooctanoate monomer [10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT) or 6-methacryloyloxyhexyl 6,8-dithiooctanoate (6-MHDT)] and a phosphonic acid monomer [6-methacryloyloxyhexyl phosphonoacetate (6-MHPA) or 6-methacryloyloxyhexyl 3-phosphonopropionate (6-MHPP)] were prepared. After treating Au, Au alloy, Ag alloy, Au-Ag-Pd alloy, and Ni-Cr alloy with the experimental primers, their shear bond strengths (SBSs) with a prosthetic light-curing resin composite (Solidex, Shofu Inc., Japan) were measured after 1-day storage followed by 5,000 thermal cycles. The SBSs between Solidex and the primer-treated metals which were incubated in air at 50°C for 2 months were further measured. Results showed that the SBSs [mean (SD)] of all metal adherends treated with primer DT-PA-1 (5.0 wt% 10-MDDT, 1.0 wt% 6-MHPA) ranged between 31.2 (5.2) and 34.5 (5.8) MPa. The SBSs of the primer-treated metals did not degrade after 2-month incubation at 50°C. Therefore, a combined primer application consisting of a dithiooctanoate monomer and a phosphonic acid monomer provided efficacious bonding to Au as well as precious and non-precious metal alloys.
Topics: Caprylates; Chromium Alloys; Composite Resins; Dental Alloys; Dental Bonding; Dental Materials; Dental Veneers; Gold Alloys; Humans; Materials Testing; Methacrylates; Organophosphonates; Organophosphorus Compounds; Palladium; Phosphonoacetic Acid; Resin Cements; Shear Strength; Silver; Sulfur Compounds; Temperature; Time Factors
PubMed: 21597216
DOI: 10.4012/dmj.2010-163 -
Antimicrobial Agents and Chemotherapy Jun 1983A plaque-reduction assay was used to examine the susceptibility of five phosphonoformic acid-resistant variants of herpes simplex virus type 1 to arabinosylnucleosides...
A plaque-reduction assay was used to examine the susceptibility of five phosphonoformic acid-resistant variants of herpes simplex virus type 1 to arabinosylnucleosides and aphidicolin. These viruses were cross-resistant to arabinosylhypoxanthine and to arabinosyladenine when tested in the absence of deoxycoformycin, a deaminase inhibitor. In the presence of deoxycoformycin, no cross-resistance between arabinosyladenine and phosphonoformic acid was observed. The two variants tested were cross-resistant to arabinosylthymine, and all five variants were collaterally susceptible to aphidicolin inhibition.
Topics: Antiviral Agents; Aphidicolin; Arabinonucleosides; Coformycin; DNA-Directed DNA Polymerase; Diterpenes; Drug Resistance, Microbial; Foscarnet; Pentostatin; Phosphonoacetic Acid; Simplexvirus; Thymidine; Thymidine Kinase; Vidarabine
PubMed: 6311091
DOI: 10.1128/AAC.23.6.914 -
Biomedizinische Technik. Biomedical... Oct 2015A deeper knowledge on the effects of the degradation of magnetic nanoparticles on their magnetic properties is required to develop tools for the identification and...
BACKGROUND
A deeper knowledge on the effects of the degradation of magnetic nanoparticles on their magnetic properties is required to develop tools for the identification and quantification of magnetic nanoparticles in biological media by magnetic means.
METHODS
Citric acid and phosphonoacetic acid-coated magnetic nanoparticles have been degraded in a medium that mimics lysosomal conditions. Magnetic measurements and transmission electron microscopy have been used to follow up the degradation process.
RESULTS
Particle size is reduced significantly in 24 h at pH 4.5 and body temperature. These transformations affect the magnetic properties of the compounds. A reduction of the interparticle interactions is observed just 4 h after the beginning of the degradation process. A strong paramagnetic contribution coming from the degradation products appears with time.
CONCLUSIONS
A model for the in vivo degradation of magnetic nanoparticles has been followed to gain insight on the changes of the magnetic properties of iron oxides during their degradation. The degradation kinetics is affected by the particle coating, in our case being the phosphonoacetic acid-coated particles degraded faster than the citric acid-coated ones.
Topics: Biomimetic Materials; Body Fluids; Citric Acid; Coated Materials, Biocompatible; Electric Impedance; Kinetics; Lysosomes; Magnetite Nanoparticles; Materials Testing; Particle Size; Phosphonoacetic Acid; Temperature
PubMed: 26035106
DOI: 10.1515/bmt-2015-0043 -
American Journal of Transplantation :... Jan 2019
Topics: Antiviral Agents; Control Groups; Cord Blood Stem Cell Transplantation; Encephalitis; Foscarnet; Ganciclovir; Herpesvirus 6, Human; Humans; Prospective Studies; Syndrome
PubMed: 30102463
DOI: 10.1111/ajt.15069 -
Clinical and Experimental Dermatology Sep 1999The outbreak of HIV infection introduced a new phenomenon in varicella zoster virus (VZV) pathology, namely the long-standing wart-like skin lesions that are frequently... (Review)
Review
The outbreak of HIV infection introduced a new phenomenon in varicella zoster virus (VZV) pathology, namely the long-standing wart-like skin lesions that are frequently associated with resistance to thymidine kinase (TK)-dependent antiviral agents. This paper reviews the clinical, histological, and molecular aspects and the therapeutic management of these verrucous lesions. The majority of lesions are characterized by chronically evolving, unique or multiple wart-like cutaneous lesions. The main histopathological features include hyperkeratosis, verruciform acanthosis and VZV-induced cytopathic changes with scant or absent cytolysis of infected keratinocytes. The mechanism that establishes the chronic nature of the lesions appears to be associated with a particular pattern of VZV gene expression exhibiting reduced or nondetectable gE and gB synthesis. Drug resistance to TK-dependent antiviral agents is a result of nonfunctional or deficient viral TK. This necessitates alternative therapeutic management using antiviral agents that target the viral DNA polymerase.
Topics: Acyclovir; Antiviral Agents; Drug Resistance, Microbial; Foscarnet; HIV Infections; Herpesvirus 3, Human; Humans; Skin Diseases, Viral
PubMed: 10564318
DOI: 10.1046/j.1365-2230.1999.00498.x -
Journal of Virology Oct 2018Epstein-Barr virus (EBV) ZEBRA protein activates the EBV lytic cycle. Cellular AP-1 proteins with alanine-to-serine [AP-1(A/S)] substitutions homologous to ZEBRA(S186)...
Epstein-Barr virus (EBV) ZEBRA protein activates the EBV lytic cycle. Cellular AP-1 proteins with alanine-to-serine [AP-1(A/S)] substitutions homologous to ZEBRA(S186) assume some functions of EBV ZEBRA. These AP-1(A/S) mutants bind methylated EBV DNA and activate expression of some EBV genes. Here, we compare expression of 67 viral genes induced by ZEBRA versus expression induced by AP-1(A/S) proteins. AP-1(A/S) activated 24 genes to high levels and 15 genes to intermediate levels; activation of 28 genes by AP-1(A/S) was severely impaired. We show that AP-1(A/S) proteins are defective at stimulating viral lytic DNA replication. The impairment of expression of many late genes compared to that of ZEBRA is likely due to the inability of AP-1(A/S) proteins to promote viral DNA replication. However, even in the absence of detectable viral DNA replication, AP-1(A/S) proteins stimulated expression of a subgroup of late genes that encode viral structural proteins and immune modulators. In response to ZEBRA, expression of this subgroup of late genes was inhibited by phosphonoacetic acid (PAA), which is a potent viral replication inhibitor. However, when the lytic cycle was activated by AP-1(A/S), PAA did not reduce expression of this subgroup of late genes. We also provide genetic evidence, using the BMRF1 knockout bacmid, that these genes are true late genes in response to ZEBRA. AP-1(A/S) binds to the promoter region of at least one of these late genes, BDLF3, encoding an immune modulator. Mutant c-Jun and c-Fos proteins selectively activate expression of EBV lytic genes, including a subgroup of viral late genes, in the absence of viral DNA replication. These findings indicate that newly synthesized viral DNA is not invariably required for viral late gene expression. While viral DNA replication may be obligatory for late gene expression driven by viral transcription factors, it does not limit the ability of cellular transcription factors to activate expression of some viral late genes. Our results show that expression of all late genes may not be strictly dependent on viral lytic DNA replication. The c-Fos A151S mutation has been identified in a human cancer. c-Fos A151S in combination with wild-type c-Jun activates the EBV lytic cycle. Our data provide proof of principle that mutant cellular transcription factors could cause aberrant regulation of viral lytic cycle gene expression and play important roles in EBV-associated diseases.
Topics: Amino Acid Substitution; Antigens, Viral; Antiviral Agents; Binding Sites; Cell Line, Tumor; DNA Methylation; DNA, Viral; Gene Expression Regulation; HEK293 Cells; Herpesvirus 4, Human; Host-Pathogen Interactions; Humans; Lymphocytes; Membrane Glycoproteins; Mutation; Phosphonoacetic Acid; Promoter Regions, Genetic; Protein Binding; Signal Transduction; Trans-Activators; Transcription Factor AP-1; Viral Proteins; Virus Replication
PubMed: 30021895
DOI: 10.1128/JVI.01062-18 -
Transport and signaling through the phosphate-binding site of the yeast Pho84 phosphate transceptor.Proceedings of the National Academy of... Feb 2010A novel concept in eukaryotic signal transduction is the use of nutrient transporters and closely related proteins as nutrient sensors. The action mechanism of these...
A novel concept in eukaryotic signal transduction is the use of nutrient transporters and closely related proteins as nutrient sensors. The action mechanism of these "transceptors" is unclear. The Pho84 phosphate transceptor in yeast transports phosphate and mediates rapid phosphate activation of the protein kinase A (PKA) pathway during growth induction. We have now identified several phosphate-containing compounds that act as nontransported signaling agonists of Pho84. This indicates that signaling does not require complete transport of the substrate. For the nontransported agonist glycerol-3-phosphate (Gly3P), we show that it is transported by two other carriers, Git1 and Pho91, without triggering signaling. Gly3P is a competitive inhibitor of transport through Pho84, indicating direct interaction with its phosphate-binding site. We also identified phosphonoacetic acid as a competitive inhibitor of transport without agonist function for signaling. This indicates that binding of a compound into the phosphate-binding site of Pho84 is not enough to trigger signaling. Apparently, signaling requires a specific conformational change that may be part of, but does not require, the complete transport cycle. Using Substituted Cysteine Accessibility Method (SCAM) we identified Phe(160) in TMD IV and Val(392) in TMD VIII as residues exposed with their side chain into the phosphate-binding site of Pho84. Inhibition of both transport and signaling by covalent modification of Pho84(F160C) or Pho84(V392C) showed that the same binding site is used for transport of phosphate and for signaling with both phosphate and Gly3P. Our results provide to the best of our knowledge the first insight into the molecular mechanism of a phosphate transceptor.
Topics: Binding Sites; Cyclic AMP-Dependent Protein Kinases; Glycerophosphates; Membrane Transport Proteins; Mutagenesis, Site-Directed; Phosphonoacetic Acid; Proton-Phosphate Symporters; Reproducibility of Results; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Signal Transduction
PubMed: 20133652
DOI: 10.1073/pnas.0906546107