acyclovir and fialuridine

We have developed a toxic, or suicide, vector whose action is based on the targeted expression of the herpes simplex virus 1 thymidine kinase gene product in cultured cells or transgenic animals. This protein is able to convert nucleoside analogs such as acyclovir and 1-(2-deoxy-2-fluoro-beta-D-arabino-furanosyl)-5-iodouracil (FIAU) to toxic intermediates. The activation of these compounds disrupts cellular DNA replication, leading to rapid cell death. Neither acyclovir, FIAU, nor the herpes thymidine kinase alone is harmful to cells. This approach is simple and should have widespread applicability in studying lineage formation in cultured cells and transgenic animals.

Topics: Acyclovir; Animals; Antiviral Agents; Arabinofuranosyluracil; Blotting, Northern; Blotting, Southern; Cell Line; Cell Line, Transformed; Cell Survival; Densitometry; DNA Replication; Gene Expression Regulation; Mice; Mice, Transgenic; Plasmids; Rats; Simplexvirus; Spleen; Thymidine Kinase; Thymus Gland; Transfection; Uridine

The three 2'-fluoropyrimidine nucleosides 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC), 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouracil (FIAU), and 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-methyluracil (FMAU), showed high activity in RK13 monolayers against equine rhinopneumonitis virus, (EHV-1, IC50 range 0.02-0.18 microM), Aujeszky's disease virus (SHV-1, pseudorabies, IC50 range 0.25-7 microM) and infectious bovine rhinotracheitis virus (1BR, BHV-1, IC50 range 0.1-3 microM). The activity of these compounds was compared with 9-(1,3-dihydroxy-2-propoxymethyl)guanine (BW B759U, DHPG) in two laboratory animal disease models: EHV-1-induced hepatitis in hamsters and SHV-1-induced encephalitis in mice. All the compounds, provided from 3 to 5 h pre-infection for 5 days, were effective in preventing EHV-1 mortality (at 3-5 mg/kg per day) and in significantly reducing SHV-1 mortality (at 60 mg/kg per day). While FIAU had the greatest activity in vitro, FMAU tended to be more potent in vivo. The reasons for these differences between relative in vitro and in vivo activities are briefly discussed.

Topics: Acyclovir; Animals; Antiviral Agents; Arabinofuranosyluracil; Cricetinae; Cytarabine; Ganciclovir; Herpesviridae Infections; Herpesvirus 1, Equid; Herpesvirus 1, Suid; Male; Mice; Pseudorabies; Pyrimidine Nucleosides

The herpes simplex virus (HSV) thymidine kinase (tk) gene was transfected into Chinese hamster ovary (CHO) 51-11 gly- cells to test its effect on the cytotoxic and mutagenic activity of anti-herpetic nucleoside analogues. Insertion of the viral tk was verified by Southern blot analysis, by sensitivity to acyclovir, and by elevated in vitro thymidine kinase (TK) activity. TK activity was increased by superinfection with a tk- virus and inhibited by antibody to viral TK. Acyclovir (ACV) was somewhat more cytotoxic in the 51-D3 cell line that expresses the viral TK than in the 51-11 parent line. Growth in ACV did not increase over background mutations at the hprt locus. FIAC (2'-fluoro-5-iodio-aracytosine) was slightly cytotoxic to the parent 51-11 line and the tk-containing clone 51-D3. FMAU (2'-fluoro-5-methyl-arauracil) had pronounced cytotoxicity in both cell lines: the 50% survival points were 1.0 microM for 51-11 cells and 0.2 microM for 51-D3. The clone 51-D3 was more sensitive than 51-11 to low concentrations of FIAU (2'-fluoro-5-iodo-arauracil), and when treated with FIAU 51-D3 had a mutation frequency to glycine independence 5 times greater than that of 51-11 cells. With both cell lines the mutation frequency at the hprt locus did not increase after growth in the presence of FIAC or FIAU. A 7-fold increase in mutation frequency at the hprt locus was detected after 51-D3 cells were grown with iododeoxyuridine. Trifluorothymidine was more toxic to 51-D3 than to 51-11 cells and increased the mutation frequency 2-fold. Cytosine-beta-D-arabinofuranoside showed no differential cytotoxicity on the two cell lines and did not increase the mutation frequency at the hprt locus.

Topics: Acyclovir; Animals; Antiviral Agents; Arabinofuranosyluracil; Cell Division; Cell Line; Cricetinae; Cricetulus; Cytarabine; DNA, Viral; Idoxuridine; Mutagenicity Tests; Nucleosides; Simplexvirus; Thymidine Kinase; Transfection; Trifluridine

Selective uptake of nucleoside analogues by herpes simplex virus infected cells may serve as the basis for a specific non-invasive diagnostic test for herpes simplex encephalitis. We have examined the effect of acyclovir on the selective uptake of [131I] 1-(2'-fluoro-2'-deoxy-beta-D-arabinofuranosyl)-5-iodouracil in herpes simplex virus infected primary rabbit kidney cells. Infected cells treated with acyclovir continued to concentrate [131I] 1-(2'-fluoro-2'-deoxy-beta-D-arabinofuranosyl)-5-iodouracil for up to 24 h after the addition of the antiviral agent. These results indicated that therapy with acyclovir for as long as 24 h would not prevent the selective trapping of nucleoside analogues. This has important implications for the use of nucleoside analogues in diagnostic brain scans to detect herpes simplex encephalitis.

Topics: Acyclovir; Animals; Arabinofuranosyluracil; Cells, Cultured; Simplexvirus; Time Factors; Uridine

Topics: Acyclovir; Animals; Antineoplastic Agents; Arabinofuranosyluracil; Cytarabine; Mammary Neoplasms, Experimental; Mice; Mice, Inbred C3H; Nucleosides; Radiation-Sensitizing Agents; Vidarabine; Whole-Body Irradiation

Seven herpes simplex virus mutants which have been previously shown to be resistant to arabinosyladenine were examined for their sensitivities to four types of antiviral drugs. These drugs were a pyrophosphate analog, four nucleoside analogs altered in their sugar moieties, two nucleoside analogs altered in their base moieties, and one altered in both. The seven mutants exhibited five distinct phenotypes based on their sensitivities to the drugs relative to wild-type strain KOS. All mutants exhibited resistance to acyclovir and arabinosylthymine, as well as marginal resistance to iododeoxyuridine, whereas all but one exhibited resistance to phosphonoformic acid. The mutants exhibited either sensitivity or hypersensitivity to other drugs tested--2'-nor-deoxyguanosine, 5-methyl-2'-fluoroarauracil, 5-iodo-2'-fluoroarauracil, and bromovinyldeoxyuridine--some of which differed only slightly from drugs to which the mutants were resistant. These results suggest ways to detect and treat arabinosyladenine-resistant isolates in the clinic. Antiviral hypersensitivity was a common phenotype. Mutations conferring hypersensitivity to 2'-nor-deoxyguanosine in mutant PAAr5 and to bromovinyldeoxyridine in mutant tsD9 were mapped to nonoverlapping regions of 1.1 and 0.8 kilobase pairs, respectively, within the herpes simplex virus DNA polymerase locus. Thus, viral DNA polymerase mediates sensitivity to these two drugs. However, we could not confirm reports of mutations in the DNA polymerase locus conferring resistance to these two drugs. All of the mutants exhibited altered sensitivity to two or more types of drugs, suggesting that single mutations affect recognition of the base, sugar, and triphosphate moieties of nucleoside triphosphates by viral polymerase.

Topics: Acyclovir; Antiviral Agents; Arabinofuranosyluracil; Arabinonucleosides; Bromodeoxyuridine; DNA-Directed DNA Polymerase; Drug Resistance, Microbial; Foscarnet; Ganciclovir; Genes, Viral; Idoxuridine; Mutation; Phosphonoacetic Acid; Simplexvirus; Thymidine; Vidarabine

The effect of several antiviral drugs on the reactivation of herpes simplex virus type 1 in explant cultures of latently infected mouse trigeminal ganglia was investigated. Phosphonoacetate and phosphonoformate, which act directly on the virus-induced DNA polymerase, require a drug concentration of 400 micrograms/ml for the inhibition of virus reactivation in latently infected ganglia. Arabinosyladenine and arabinosyladenine monophosphate, which are phosphorylated to triphosphates by cellular enzymes and inhibit virus synthesis either by blocking the DNA polymerase or by incorporation into viral DNA, require a concentration of only 100 micrograms/ml for the inhibition of the reactivation process. Drugs that are phosphorylated by the virus-induced thymidine kinase, such as acyclovir, arabinosylthymine, bromovinyldeoxyuridine, and three fluorinated pyrimidine nucleosides require the lowest drug concentrations for complete inhibition of virus reactivation in latently infected ganglia explant cultures. Our data suggest that the inhibition of virus reactivation is dependent not only on drug concentration, but also on the number of latently infected neurons in the ganglia.

Topics: Acyclovir; Animals; Antibodies, Viral; Antiviral Agents; Arabinofuranosyluracil; Arabinonucleosides; Bromodeoxyuridine; Culture Media; Culture Techniques; Cytarabine; Foscarnet; Mice; Mice, Hairless; Neutralization Tests; Phosphonoacetic Acid; Simplexvirus; Thymidine; Trigeminal Nerve; Vidarabine Phosphate; Virus Activation

FIAC [1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine], FIAU [1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-iodouracil], and FMAU [1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-methyluracil] were evaluated for their efficacies in the treatment of genital infections with herpes simplex virus type 2 in guinea pigs. Intraperitoneal administration of these drugs in daily doses of 100 mg/kg of body weight initiated 24 h after virus inoculation and repeated 2 successive days thereafter inhibited development of genital lesions and reduced shedding of virus without evoking untoward reactions. In a comparative study with this 3-day dosage schedule, the efficacy of daily doses of 50 mg of FMAU per kg was greater than that of the same doses of FIAC and FIAU, in that order; all these were more effective than daily doses of 50, 100, or 200 mg of acyclovir or of 500 mg of phosphonoformic acid per kg. These differences in efficacy were enhanced when treatment was delayed for 2 to 3 days after inoculation.

Topics: Acyclovir; Animals; Antiviral Agents; Arabinofuranosyluracil; Cytarabine; Female; Foscarnet; Guinea Pigs; Herpes Genitalis; Injections, Intraperitoneal; Male; Phosphonoacetic Acid; Uridine; Virus Replication