Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Viral infections, predominantly those of the herpes virus family, account for up to 16% of all clinically significant infections in AIDS patients. Acyclovir has provided successful treatment in AIDS patients suffering from severe herpes simplex and herpes zoster virus infections. Preliminary results are presented on newly developed acyclovir analogues. Desciclovir, an oral prodrug of acyclovir which is metabolized to acyclovir in vivo, allows treatment of virus infections per os, where high serum levels are needed, e.g. in Epstein-Barr virus infections. BW B759U, another analogue of acyclovir, has been used for the treatment of life-threatening or sight-threatening cytomegalovirus infections in AIDS patients. More than 80% of the patients treated for retinitis experienced stabilization or clinical improvement. Antiviral efficacy was demonstrated in 73% of the patients. Azidothymidine, a nucleoside analogue of thymidine, has been developed specifically to treat the HIV infection. Its antiviral activity is based on inhibition of reverse transcriptase. Phase I studies have demonstrated that azidothymidine is well tolerated. Its ability to cross the blood brain barrier makes it an attractive candidate for treatment of HIV. Trials to determine efficacy are in progress.
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PMID:Management of viral infections in AIDS patients. 303 16

A study was undertaken to assess the etiology, optimal diagnostic method, and incidence of healing of perianal ulcers in HIV-seropositive men. Between March 1990 and December 1991, 26 HIV-seropositive homosexual or bisexual males were referred with perianal ulcerations. According to CDC criteria, three (12 percent) were Class II, six (23 percent) were Class III, and 17 (65 percent) were Class IV. Eighteen patients had one ulcer, five had two ulcers, and two had three ulcers. In one patient the ulcer was circumanal. Patients with superficial erosions were not included. Biopsies were obtained in 23 patients for routine microscopy, HIV, cytomegalovirus, herpes simplex virus, and acid-fast bacilli. Biopsy revealed an immunoblastic lymphoma in one patient. A comparison of microscopy and culture results revealed culture to be more helpful in determining the etiology of these ulcers. Medical treatment included reverse transcriptase inhibitors (zidovudine, dideoxyinosine, and dideoxycytosine), oral and topical Zovirax (Burroughs Wellcome, Research Triangle Park, NC), ganciclovir, and oral broad-spectrum antibiotics. Surgical treatment included lateral internal sphincterotomy in three patients and seton placement in one patient. Follow-up for at least four weeks was obtained in 22 patients. Overall, healing occurred in 15 patients (68 percent): three (20 percent) were Class II, four (27 percent) were Class III, and eight (53 percent) were Class IV. Healing occurred in all four patients who underwent surgical treatment. In conclusion, aggressive diagnostic maneuvers allow the use of both medical and conservative surgical measures to successfully treat the majority of perianal ulcers in this patient population.
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PMID:Is aggressive management of perianal ulcers in homosexual HIV-seropositive men justified? 844 27

Acyclovir is an effective drug for the treatment of HSV and VZV infections, which after phosphorylation to the triphosphate, inhibits viral DNA polymerase. Acyclovir has low oral bioavailability, therefore prodrugs have been developed, and the L-valyl ester, valaciclovir, recently has been licensed for the treatment of shingles. Ganciclovir is used against CMV, and famciclovir, a lipophilic prodrug of penciclovir, is marketed for shingles. The acyclic nucleoside phosphonates are active against thymidine kinase-resistant viral strains. Promising analogs are PMEA (in clinical trial for the treatment of AIDS) and (S)-HPMPC (good in vivo activity against HSV, VZV, CMV, and EBV). Oligonucleotides incorporating acyclic nucleosides at the 3'-and 5'-ends, or constituted of amino acyclic nucleosides, are resistant to cleavage by nucleases and may be useful in antisense and/or antigene therapy. HEPT is active against HIV-1: It binds in a hydrophic pocket on reverse transcriptase, rather than in the polymerase active site. Some acyclic nucleosides are potent inhibitors of purine and pyrimidine nucleoside phosphorylase. These compounds may have a therapeutic niche in combination therapy with antiviral and anticancer nucleosides, and in the treatment of diseases involving the T-cell.
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PMID:Acyclic nucleosides as antiviral compounds. 873 25

For many years, acyclovir has been used to treat herpes simplex and varicella zoster infections in adults and children, although new drugs with improved bioavailability and dosage regimens (ie, famciclovir, valaciclovir) are replacing it for the outpatient management of these conditions in adults. Acyclovir remains the treatment of choice for severe herpes infections in both immunocompetent and immunosuppressed patients. Data on the newer antiherpes drugs in children are not available. Treatment of severe cytomegalovirus infections with ganciclovir and foscarnet is difficult because of toxicity; whether improved formulations of these drugs or newer agents prove clinically useful remains to be seen. For the most part, treatment of other herpesviruses is not indicated. The major advance in pediatric HIV treatment is the reduction in vertical transmission with peripartum zidovudine, although the optimal use of antiretrovirals in this situation remains to be determined. The nucleoside analogues zidovudine, zalcitabine, didanosine, and stavudine have been assessed in HIV-infected children; pediatric data about appropriate combinations (eg, with the protease inhibitors and the nonnucleoside reverse transcriptase inhibitors) and dosage regimens lag well behind the adult literature. The effectiveness of ribavirin in respiratory syncytial virus disease is uncertain. Preliminary data suggest that interferons may have a role in the management of chronic hepatitis B and C.
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PMID:Advances in antiviral therapy. 908 51

Acyclovir is an antiviral agent that causes termination of viral DNA synthesis by inhibiting viral reverse transcriptase. Acyclovir is used therapeutically to treat herpes simplex, cytomegalovirus, Epstein-Barr, and varicella-Zoster. Although acyclovir is thought to be low in toxicity, it has caused an obstructive nephropathy from accumulation of crystals in renal tissue. A retrospective review (January 1995 through March 2000) was conducted of acyclovir toxicoses in dogs reported to the ASPCA National Animal Poison Control Center. Of 105 ingestions, 10 were considered cases of acyclovir toxicosis. The most common signs seen were vomiting, diarrhea, anorexia, and lethargy. Ingested dosages ranged from 40 to 2195 mg/kg bw. Polyuria and polydipsia were reported in I dog. In 6/10 cases, signs developed within 3 h of ingestion. Treatment included standard decontamination procedures, (ie induction of emesis, administration of activated charcoal), diuresis, and supportive care.
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PMID:Accidental ingestion of acyclovir in dogs: 105 reports. 1111 48

For most viruses, there is a need for antimicrobials that target unique viral molecular properties. Acyclovir (ACV) is one such drug. It is activated into a human herpesvirus (HHV) DNA polymerase inhibitor exclusively by HHV kinases and, thus, does not suppress other viruses. Here, we show that ACV suppresses HIV-1 in HHV-coinfected human tissues, but not in HHV-free tissue or cell cultures. However, addition of HHV-6-infected cells renders these cultures sensitive to anti-HIV ACV activity. We hypothesized that such HIV suppression requires ACV phosphorylation by HHV kinases. Indeed, an ACV monophosphorylated prodrug bypasses the HHV requirement for HIV suppression. Furthermore, phosphorylated ACV directly inhibits HIV-1 reverse transcriptase (RT), terminating DNA chain elongation, and can trap RT at the termination site. These data suggest that ACV anti-HIV-1 activity may contribute to the response of HIV/HHV-coinfected patients to ACV treatment and could guide strategies for the development of new HIV-1 RT inhibitors.
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PMID:Acyclovir is activated into a HIV-1 reverse transcriptase inhibitor in herpesvirus-infected human tissues. 1877 44

The antiviral drug acyclovir is a guanosine nucleoside analog that potently inhibits herpes simplex virus (HSV) replication. Acyclovir treatment in patients coinfected with HSV and human immunodeficiency virus (HIV) has been observed to alter disease course and decrease HIV viral load, a finding that has been attributed to indirect effects of HSV suppression on HIV replication. Based on this hypothesis, several clinical studies have recently investigated the use of acyclovir for treatment of patients coinfected with HSV and HIV or for prophylaxis against HIV transmission. In this report, we use a single round HIV infectivity assay to show that acyclovir directly inhibits HIV infection with an IC50 of approximately 5 microm. The target of acyclovir in HIV-infected cells is validated as HIV reverse transcriptase (RT) by the emergence of the RT variant V75I under the selective pressure of acyclovir. The V75I mutation is part of the multidrug resistance pathway that enhances viral resistance to many of the best RT inhibitors approved for the treatment of HIV. Biochemical analyses demonstrate that acyclovir triphosphate is a chain terminator substrate for HIV RT and can compete with dGTP for incorporation into DNA. Although acyclovir may prove a useful lead for development of new HIV treatments, the selection of resistant mutants raises a cautionary note to the use of acyclovir monotherapy in patients coinfected with HSV and HIV.
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PMID:The antiherpetic drug acyclovir inhibits HIV replication and selects the V75I reverse transcriptase multidrug resistance mutation. 1881 98

Acyclovir, a nucleoside analog, is thought to be specific for the human herpesviruses because it requires a virally encoded enzyme to phosphorylate it to acyclovir monophosphate. Recently, acyclovir triphosphate was shown to be a direct inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. Here, we showed that acyclovir is an inhibitor of HIV-1 replication in CD4(+) T cells from cord blood that have undetectable levels of the eight human herpesviruses. Additionally, acyclovir phosphates were detected by reverse-phase-high performance liquid chromatography (RP-HPLC) and quantified in a primer extension assay from cord blood. The data support acyclovir as an inhibitor of HIV-1 replication in herpesvirus-negative cells.
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PMID:Consistent inhibition of HIV-1 replication in CD4+ T cells by acyclovir without detection of human herpesviruses. 2132 17

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