Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acyclovir, an acrylic purine nucleoside analog, is a highly potent inhibitor of herpes simplex virus (HSV), types 1 and 2, and varicella zoster virus, and has extremely low toxicity for the normal host cells. This selectivity is due to the ability of these viruses to code for a viral thymidine kinase capable of phosphorylating acyclovir to a monophosphate; this capability is essentially absent in uninfected cells. The acyclovir monophosphate (acyclo-GMP) is subsequently converted to acyclovir triphosphate (acyclo-GTP) by cellular enzymes. Acyclo-GTP persists in HSV-infected cells for many hours after acyclovir is removed from the medium. The amounts of acyclo-GTP formed in HSV-infected cells are 40 to 100 times greater than in uninfected Vero cells. Acyclo-GTP acts as a more potent inhibitor of the viral DNA polymerases than of the cellular polymerases. The DNA polymerases of HSV-1 and HSV-2 also use acyclo-GTP as a substrate and incorporate acyclo-GMP into the DNA primer-template to a much greater extent than do the cellular enzymes. The viral DNA polymerase binds strongly to the acyclo-GMP-terminated template, and in thereby inactivated.
 ...
PMID:Mechanism of action and selectivity of acyclovir. 628 36

9-([2-Hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine (2'-nor-2'-deoxyguanosine; 2'NDG) selectively inhibits the replication of herpes group viruses. In cell culture studies 2'NDG was at least 10-fold more potent than acyclovir (ACV) in inhibition of human cytomegalovirus replication and Epstein-Barr virus-induced lymphocyte transformation and was about as effective as ACV in inhibition of herpes simplex viruses 1 and 2 and varicella zoster virus. Orally administered 2'NDG was 6- to 50-fold more efficacious than ACV in treating systemic or local HSV-1 infection or HSV-2 intravaginal infection in mice. The mode of action of 2'NDG appears to involve phosphorylation by herpes simplex virus thymidine kinase and subsequent phosphorylations by cellular kinases to produce 2'NDG triphosphate, which is a potent inhibitor of herpes virus DNA polymerase. Compared to ACV, 2'NDG was a more efficient substrate for HSV-1 thymidine kinase (Vmax/Km for 2'NDG 30-fold higher than that of ACV), whereas 2'NDG monophosphate is a more efficient substrate for GMP kinase (Vmax/Km for 2'NDG monophosphate 492-fold higher than that for ACV monophosphate). The combined effect is more rapid production of the inhibitory triphosphate from 2'NDG than from ACV.
 ...
PMID:9-([2-hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine: a selective inhibitor of herpes group virus replication. 630 64

Acyclovir, the new virucidal drug recently approved by the Food and Drug Administration for the treatment of herpes simplex virus (HSV), is the first available effective drug to treat such infections. Acyclovir boasts activity against four of the five major herpes-group viruses, including herpes simplex (types 1 and 2), varicella-zoster, and Epstein-Barr. The drug, phosphorylated preferentially in viral cells, exclusively attacks infected cells possessing virus-specific DNA polymerase, giving acyclovir low toxicity coupled with high efficacy. Problems of renal toxicity and viral resistance now dampen some of the initial expectations. Present-day research continues to reveal insights into the mechanism and action of acyclovir.
 ...
PMID:Acyclovir. 630 47

3'-NH2-BV-dUrd, the 3'-amino derivative of (E)-5-(2-bromovinyl)-2'-deoxyuridine, was found to be a potent and selective inhibitor of herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) replication. 3'-NH2-BV-dUrd was about 4-12 times less potent but equally selective in its anti-herpes activity as BV-dUrd. Akin to BV-dUrd, 3'-NH2-BV-dUrd was much less inhibitory to herpes simplex virus type 2 than type 1. It was totally inactive against a thymidine kinase-deficient mutant of HSV-1. The 5'-triphosphate of 3'-NH2-BV-dUrd (3'-NH2-BV-dUTP) was evaluated for its inhibitory effects on purified herpes viral and cellular DNA polymerases. Among the DNA polymerases tested, HSV-1 DNA polymerase and DNA polymerase alpha were the most sensitive to inhibition by 3'-NH2-BV-dUTP (Ki values 0.13 and 0.10 microM, respectively). The Km/Ki ratio for DNA polymerase alpha was 47, as compared with 4.6 for HSV-1 DNA polymerase. Thus, the selectivity of 3'-NH2-BV-dUrd as an anti-herpes agent cannot be ascribed to a discriminative effect of its 5'-triphosphate at the DNA polymerase level. This selectivity most probably resides at the thymidine kinase level. 3'-NH2-BV-dUrd would be phosphorylated preferentially by the HSV-1-induced thymidine kinase (Ki 1.9 microM, as compared with greater than 200 microM for the cellular thymidine kinase), and this preferential phosphorylation would confine the further action of the compound to the virus-infected cell.
 ...
PMID:Antiviral activity of the 3'-amino derivative of (E)-5-(2-bromovinyl)-2'-deoxyuridine. 630 80

Acyclovir (acycloguanosine) is a new antiviral compound with activity against certain herpes viruses. Acyclovir is phosphorylated preferentially in virus-infected cells into its active form, acyclovir triphosphate, an inhibitor of viral-induced DNA polymerase. Acyclovir, which possesses an acyclic carbohydrate moiety, also causes premature DNA chain termination. Acyclovir has shown clinical activity against herpes simplex virus (HSV) types 1 and 2 and varicella zoster virus (VZV), but its usefulness in cytomegalovirus, Epstein-Barr virus, and chronic hepatitis B infections requires further study. In randomized clinical trials of infections caused by HSV and VZV, intravenous acyclovir has been shown to shorten the duration of viral shedding and lesion pain and hasten the resolution of skin lesions, with minimal toxicity.
 ...
PMID:The clinical use of intravenous acyclovir. 631 3

Mutants of Varicella-Zoster Virus (VZV) which are resistant to phosphonoacetic acid (PAA), bromodeoxyuridine (BuDR), and acyclovir (ACV) were obtained by serial passages of VZV with increasing concentrations of these drugs. A PAA-resistant mutant and a BuDR-resistant mutant were found also to be resistant to ACV. Five of 8 ACV-resistant mutants acquired resistance to PAA, but none acquired resistance to BuDR. The BuDR-resistant mutant did not induce viral thymidine kinase (TK) activity, but all the ACV-resistant mutants selected in ACV showed viral TK activity which was suppressed with anti-VZV serum and had almost the same electrophoretic mobility as that of the parent strain on polyacrylamide gel electrophoresis in non-denaturing conditions. However, in competitive TK assay with ACV, 2 of 8 ACV-resistant mutants showed no change of phosphorylation of radioactive thymidine, while the other 6 showed decreased phosphorylation of radioactive thymidine. It was suggested that TK induced by the former 2 ACV-resistant mutants had lost affinity to ACV, and so the mutants could grow in the presence of ACV. Thus of the 8 ACV-resistant mutants selected in ACV, 2 were sensitive to PAA with altered TK activity, 5 were resistant to PAA with unaltered TK activity, and 1 was sensitive to PAA with unaltered TK activity, and may have altered DNA polymerase activity to ACV, retaining sensitivity to PAA. These results suggest that resistance of VZV to ACV results from alterations in the virus-specified TK or DNA polymerase, as demonstrated in HSV resistant to ACV.
 ...
PMID:Isolation of drug resistant mutants of varicella-zoster virus: cross resistance of acyclovir resistant mutants with phosphonoacetic acid and bromodeoxyuridine. 631 58

Acyclovir, 9-(2-hydroxyethoxymethyl)guanine, is an acyclic nucleoside analogue which has a high activity and selectivity for herpes viruses, particularly herpes simplex viruses types 1 and 2 and varicella zoster virus. This selectivity is due to the initial activation of the drug by phosphorylation by a herpes virus-specified thymidine kinase. Normal cellular enzymes do not phosphorylate acyclovir to any significant degree. Acyclovir monophosphate is subsequently converted to a triphosphate which is a more potent inhibitor of herpes virus DNA polymerases than of cellular DNA polymerases. The relationship between the amount of acyclovir triphosphate formed and its inhibition constant (Ki) for the particular viral or cellular DNA polymerase is predictive of the inhibitory activity of acyclovir on DNA replication.
 ...
PMID:The biochemistry and mechanism of action of acyclovir. 631

Acyclovir (Zovirax) is a qualified success as an effective and nontoxic antiviral chemotherapeutic agent and at present is approved for the treatment of initial genital herpes and limited life-threatening cutaneous herpes simplex viral infections in the immunocompromised host. Its efficacy in Epstein-Barr, varicella-zoster, and cytomegalorvirus infections appears less promising. According to one controlled study, its efficacy in the treatment of herpes labialis (HSV-1) infections has been disappointing. The highly selective action of acyclovir against viral DNA polymerase and its inhibition of viral DNA chain elongation result in a low incidence of human (host cell) toxicity, as manifested by local irritation at injection sites and a modest incidence of adverse renal effects, which can be reduced by judicious drug use. Newer antiviral agents now under development hold substantial promise for the future of antiviral chemotherapy.
 ...
PMID:Acyclovir and herpesvirus infections. A review of the literature. 632 78

Acyclovir is a new antiviral drug that acts as a specific inhibitor of herpesvirus DNA polymerase. It shows good in vitro activity against herpes simplex and varicella-zoster viruses. The drug may be administered topically to the skin, intravenously, orally, or topically to the eye (only topical and intravenous preparations are currently available). Acyclovir kinetics are described by a two-compartment open model. The drug and its metabolites are excreted by the kidney via glomerular filtration and tubular secretion. Dosage adjustment is required in patients with renal failure. Safety and tolerance studies in animals and humans have shown acyclovir to be very well tolerated. The most important adverse effect is crystalluria and elevated serum creatinine related to bolus intravenous administration. Other reported adverse effects include infusion site inflammation and rash. Topical acyclovir is effective for treating initial genital herpes and mucocutaneous herpes in the compromised host, but has not been shown to be clinically useful for recurrent labial or genital herpes. Intravenous acyclovir is effective for mucocutaneous herpes infections in the compromised host and initial genital herpes in the normal host; it is being evaluated for the treatment of herpes simplex virus encephalitis and varicella-zoster infections. An investigational oral preparation may prove to be effective therapy for both initial and recurrent genital herpes. Acyclovir therapy does not eliminate latent virus or prevent subsequent recurrences.
 ...
PMID:Acyclovir: mechanism of action, pharmacokinetics, safety and clinical applications. 635 82

DNA sequence analysis revealed a gene encoding the Marek's disease virus (MDV) DNA polymerase (pol) within the BamHI-E fragment of the long unique region of the virus genome. Identification is based on an extensive amino acid homology between the MDV open reading frame and the DNA pol (UL30) of the herpes simplex virus. We describe here a 3540-base-pair fragment of the MDV DNA encoding 1180 amino acids with a M(r) of 133,920 daltons as the viral DNA pol gene, with the analysis of transcription and translation. In Northern blot hybridization, a transcript of 4.0 kb was detected in GA-MDV-infected duck embryo fibroblast (DEF) cells. An antiserum was generated in rabbit using TryE-pol fusion protein expressed in E. coli. This antiserum specifically immunoprecipitated a protein of 135 kD from lysates of MDV-GA-infected DEF cells. MDV DNA pol showed extensive homology to five distantly related herpesviruses: equine herpesvirus (EHV), varicella-zoster virus (VZV), herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV), and human cytomegalovirus (HCMV). Comparison of amino acid sequences among the herpesviruses highlights nine highly conserved regions. Three of the conserved regions are in the N-terminus in the 3'-5' exonuclease domains and the remaining six are in the C-terminus in the catalytic domains. The predicted structural characters are in good agreement with the published data on a number of human herpesvirus DNA pol. The identification of MDV DNA pol gene may lead to a better understanding of MDV replication.
 ...
PMID:Identification and characterization of a Marek's disease virus gene encoding DNA polymerase. 765 4


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>