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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The polymerase chain reaction (PCR) was used to investigate samples from Indonesian and Swedish patients with cervical intraepithelial neoplasia grade III (CIN III), squamous cell carcinoma or adenocarcinoma of the cervix for the presence of a transforming fragment (BC 24) of herpes simplex virus type 2 (HSV-2) DNA. The PCR test for HSV-2 DNA was more sensitive than the infectivity endpoint titer in a cell culture system and no cross reactivity was found with either varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human papillomavirus 16 or 18, or human genomic DNA. Using this PCR test, 2 out of 5 cases with CIN III, 10 of 71 squamous cell carcinomas, and 3 of 11 adenocarcinomas of the uterine cervix were found to contain DNA sequences homologous to the BC 24 fragment of the HSV-2 genome. Only two of the samples containing this transforming region of the HSV-2 DNA were positive in a PCR assay for the HSV-2 DNA polymerase gene. The great majority of the HSV-2 BC 24 DNA positive (12 of 15) came from the Indonesian group of patients. All 15 CIN III or cancer samples positive for the HSV-2 BC 24 fragment were also positive for papillomavirus DNA. In line with observations made by others, our data support the hypothesis that HSV infection could represent one of several possible oncogenic cofactors leading to cervical carcinoma. The HSV cofactor might be more important in the Indonesian than in the Swedish population.
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PMID:Detection of the BC 24 transforming fragment of the herpes simplex virus type 2 (HSV-2) DNA in cervical carcinoma tissue by polymerase chain reaction (PCR). 779 6

Thymidine kinase (TK)-negative (TK-) mutant strains of herpes simplex virus type 1 (HSV-1) show reduced expression of alpha and beta viral genes during acute infection of trigeminal ganglion neurons following corneal infection (M. Kosz-Vnenchak, D. M. Coen, and D. M. Knipe, J. Virol. 64:5396-5402, 1990). It was surprising that a defect in a beta gene product would lead to decreased alpha and beta gene expression, given the regulatory pathways demonstrated for HSV infection of cultured cells. In this study, we have examined viral gene expression during reactivation from latent infection in explanted trigeminal ganglion tissue. In explant reactivation studies with wild-type virus, we observed viral productive gene expression over the first 48 h of explant incubation occurring in a temporal order (alpha, beta, gamma) similar to that in cultured cells. This occurred predominantly in latency-associated transcript-positive neurons but was limited to a fraction of these cells. In contrast, TK- mutant viruses showed greatly reduced alpha and beta gene expression upon explant of latently infected trigeminal ganglion tissue. An inhibitor of viral TK or an inhibitor of viral DNA polymerase greatly decreased viral lytic gene expression in trigeminal ganglion tissue latently infected with wild-type virus and explanted in culture. These results indicate that the regulatory mechanisms governing HSV gene expression are different in trigeminal ganglion neurons and cultured cells. We present a new model for viral gene expression in trigeminal ganglion neurons with implications for the nature of the decision process between latent infection and productive infection by HSV.
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PMID:Evidence for a novel regulatory pathway for herpes simplex virus gene expression in trigeminal ganglion neurons. 839 54

To determine the diagnostic value of the polymerase chain reaction (PCR) in establishing the rapid diagnosis of herpes simplex virus encephalitis (HSE) in the pediatric age group, we performed PCR to detect herpes simplex virus (HSV) in the cerebrospinal fluid of 8 neonates with HSV infection (4 with central nervous system involvement), 11 infants and children with suspected HSE (4 proved, 1 presumed, 6 excluded), and 105 control patients who had cerebrospinal fluid obtained as part of the evaluation for other diagnoses. The HSV DNA was amplified and typed by using primers specific for the DNA polymerase gene of HSV types 1 and 2. Herpes simplex virus DNA was detected in the cerebrospinal fluid of 3 of 4 neonates with CNS involvement (all with HSV type 2) and 3 of the 4 patients with proved HSE (all with HSV type 1). No HSV DNA was detected in the 4 neonates without CNS disease, the 1 patient with presumed HSE, the 6 patients who had HSE excluded from the diagnosis, and the 105 control patients. Overall, HSV PCR had a sensitivity of 75%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 98%. These results indicate that PCR is a useful noninvasive test in establishing the diagnosis of acute HSE, but a negative result did not exclude the diagnosis.
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PMID:Rapid diagnosis of herpes simplex virus encephalitis by using the polymerase chain reaction. 812 Jul 29

This study reports the successful use of three sets of primers, each from different genes on the herpes simplex virus (HSV) genome, 1) the DNA polymerase gene, 2) the glycoprotein B gene, and 3) the glycoprotein D gene, for detection of HSV DNA by polymerase chain reaction (PCR). All three sets of primers detected the same HSV DNA in the throat and genital specimens. Using the conventional viral culture as a standard, PCR provided a sensitivity of 100% and a specificity of 100% in this study. In addition, a nested-PCR protocol using two sets of primers in the glycoprotein D gene, one set internal to the other, was evaluated for the amplification of HSV DNA in cerebrospinal fluid (CSF) from patients suspected of having herpes simplex encephalitis (HSE). Five of the 10 CSF specimens tested were found positive. In conclusion, PCR detection is a valuable tool for rapid diagnosis of HSV infection, especially for CSF specimens.
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PMID:Rapid detection of herpes simplex virus by polymerase chain reaction. 1156 82

A 45-year-old matched unrelated BMT recipient had sequential mucocutaneous herpes simplex virus (HSV) type 2 infections. Five months after BMT, a penile lesion occurred and was cured using acyclovir, as expected from in vitro susceptibility results. The same lesion recurred 1 month later but worsened with acyclovir. The HSV isolate was resistant to acyclovir (IC(50) = 105 microM), and a nucleotide (G) was added to the thymidine kinase gene leading to a premature stop codon. The lesion improved markedly with foscarnet. During this treatment a second HSV infection occurred on the buttocks 2 weeks after the first one and healed completely with acyclovir. This course correlated with in vitro results of the buttock HSV isolate which was foscarnet-resistant (IC(50) = 300 microg/ml) and acyclovir-sensitive. Surprisingly, no mutation gene of the foscarnet-resistant isolate was detected in the DNA polymerase gene. This case shows that an HSV acyclovir-resistant infection may be followed by an acyclovir-sensitive one. Determination of antiviral susceptibility is needed to monitor the treatment of various HSV infections in immunocompromised BMT recipients.
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PMID:Multiple herpes simplex virus infections with various resistance patterns in a matched unrelated donor transplant recipient. 1178 35

A susceptible individual exposed to herpes simplex virus (HSV) will develop latent infection in multiple cranial nerve ganglia. There are a few quantitative studies of the viral load within the trigeminal ganglion, but none that investigate other cranial nerve ganglia. In this study, human trigeminal, geniculate, vestibular (Scarpa's) and cochlear (spiral) ganglia were obtained from willed body donors. Real time quantitative polymerase chain reaction (PCR) analysis of the HSV DNA polymerase gene was performed on ipsilateral ganglion sets from the same individual. Viral load, expressed as HSV genomes per 105 cells, was significantly greater in the vestibular ganglion (mean +/- SD, 176705 +/- 255916) than in the geniculate (9948 +/- 22066), cochlear (3527 +/- 9360), or trigeminal (2017 +/- 5578) ganglia. There was not a significant correlation among ganglia from the same individual. The results support the hypothesis that neuronal subpopulations have variable susceptibility to HSV infection.
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PMID:Quantitative analysis of herpes simplex virus in cranial nerve ganglia. 1537 Nov 51

Human herpesviruses can be found worldwide and cause many viral infections in immunocompetent as well as in immunocompromised patients. Herpes simplex virus (HSV) diseases can be the cause of life-threatening disease, especially in neonates. After initial infection, HSV persists latently in host neurons with the risk of periodical reactivation over a lifetime. The development of acyclovir, a potent and specific nucleoside inhibitor of the herpes DNA polymerase, was a milestone in the history of antiviral drugs in the late 1970s. During the last decades a better understanding of the replication and disease-causing state of HSV types 1 and 2 has been achieved enabling the development of new and potent antiviral compounds. In the mid-1990s, for example, valacyclovir and famciclovir were launched as prodrugs of acyclovir with improved bioavailability. Despite the numerous drugs available for the systemic treatment of HSV infections, the topical application of a cream containing an antiviral agent is still the most convenient method of treating herpes simplex labialis/facialis in the general population. For some time, the topical standard treatment for recurrent HSV infections has been acyclovir cream, despite the fact that the evidence for efficacy in recurrent episodes has been equivocal. Penciclovir, a novel acyclic nucleoside analogue, has demonstrated efficacy against HSV types 1 and 2 and seems to have a pharmacological advantage due to a prolonged half-life of its active form in HSV-infected cells. This review discusses and compares the topical treatment modalities available for HSV infections. As a conclusion, different studies are available that have shown that it is possible to reduce viral replication and hasten lesion resolution with 1% penciclovir treatment beyond the prodromal phase of the HSV infection. Comparing data of topical treatment with acyclovir and penciclovir revealed a superiority for penciclovir cream showing a significant decrease in time to lesion healing, lesion area and pain. While systemic acyclovir or valacyclovir may be valid drugs especially for HSV prophylaxis, 1% penciclovir cream should be preferred as topical treatment since there are good therapeutic results independent of the phase of development of herpetic eruptions.
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PMID:Penciclovir cream--improved topical treatment for herpes simplex infections. 1545 7

Herpes virus hepatitis (HSV) represents a form of acute necrotizing hepatitis, which most frequently develops in immunocompromised patients. Therapeutic options include high-dose intravenous acyclovir and liver transplantation. We report the first case of recurrent HSV hepatitis after liver retransplantation, which occurred despite continuous administration of high-dose intravenous antiviral therapy. Because explant histology pointed to initial therapy response, we thought that the reason for recurrence might be due to acyclovir resistance. Most acyclovir resistance is caused by inactivating mutations in the herpes virus thymidine kinase gene. HSV infection was detected by histology and proofed by immunohistochemistry. PCR amplification of the herpes virus thymidine kinase gene was performed on histology specimens to demonstrate the course of viral infection in liver tissue. Genotypic resistance testing of the herpes virus was performed by sequencing the thymidine kinase amplicon. In serial biopsy, HSV-DNA sequences were only detectable when histology revealed herpes hepatitis. Whereas the primary explant exhibited the wild-type thymidine kinase gene, a biopsy of the second graft one month after retransplantation, which showed recurrent herpes virus hepatitis, had a single base insertion within a homopolymeric cytosine stretch. This mutation causes a frame shift leading to a premature stop codon and results in a known acyclovir-resistant herpes strain. In conclusion, we believe that testing for acyclovir-resistant herpes strains should be considered in high-risk patients in whom viral clearance is not achieved serologically to prevent fatal recurrence of disease by using antiviral drugs such as inhibitors of HSV-DNA polymerase or viral helicase primase inhibitors.
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PMID:Recurrent herpes simplex virus hepatitis after liver retransplantation despite acyclovir therapy. 1618 58

Herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) are members of the Herpesviridae family. HSV infections have been known since ancient times and are one of the most common communicable diseases in humans. Although infections are often subclinical, HSV can cause mild to severe diseases, especially in immunocompromised patients. Herpes simplex viruses establish latency in the nuclei of neuronal cells and may reactivate, with or without symptoms, throughout the host's lifetime. Over one third of the world's population suffer from recurrent HSV infections several times a year and are thus capable of transmitting HSV by close personal contact. There are few drugs licensed for the treatment of HSV infections. Most target the viral DNA polymerase, and indeed acyclovir remains the reference treatment some thirty years after its discovery! Extensive clinical use of this drug has led to the emergence of resistant viral strains, mainly in immunocompromised patients. This highlights the crucial need for the development of new anti-herpes drugs that can inhibit infection by both wild-type viruses and drug-resistant strains. Over the last few years, significant efforts have been made to set up a range of strategies for the identification of potential new anti-viral drugs. One alternative is to develop drugs with different mechanisms of action. The present article reviews potential viral and cellular targets that are now known to be involved in HSV infection and for which specific inhibitors with anti-HSV activity, at least in cell culture, have been identified.
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PMID:Novel targets for the development of anti-herpes compounds. 1734 7

Most of the current antiherpetics target viral DNA polymerase, but with the emergence of drug-resistant viruses, antiherpetics with different targets have become necessary. Inhibition of herpes simplex virus (HSV) replication at the early stages of infection minimizes cytotoxicity and immune suppression induced by HSV infection. In this report, quantitative reporter systems that use recombinant HSV and a stably transfected cell line were developed for the screening of agents targeting the early stages of HSV infection. The reporter genes in both systems were directed by HSV immediate-early (IE) promoters, so considerably less time was required for the quantification of HSV infection than the traditional plaque reduction assay. The results show that both reporter assays were sensitive to antiherpetic screening. Both assays were quantitative, rapid, easy to perform, and highly adaptable for automatic high-throughput screening. Exploiting the flexibility of these 2 assays, modified assays were also proposed for the detailed analysis of antiherpetic mechanisms.
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PMID:Herpes simplex virus (HSV) immediate-early (IE) promoter-directed reporter system for the screening of antiherpetics targeting the early stage of HSV infection. 2054 35


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