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:2.7.1.21 (thymidine kinase)
7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA sequence analysis and 5'-end mapping of mRNA were used to identify and clone DNA fragments which contain the presumptive promoter (Pgl) and poly(A) site (An) of the bovine herpesvirus 1 (BHV1) gl glycoprotein. To confirm the presence of these regulatory regions in the above fragments, they were cloned together with a chloramphenicol acetyltransferase (CAT) reporter gene into pUC19. The recombinant plasmid formed, pEC3, was capable of inducing CAT activity when transfected into bovine cells demonstrating that the Pgl-CAT-An sequence constituted a functional CAT expression cassette. The cassette was excised from pEC3, transferred to a plasmid insertion vector (pIV3A) and subsequently inserted into the thymidine kinase (tk) gene of BHV1. Insertion in either orientation, relative to the tk gene, gave rise to BHV1 recombinants which expressed CAT activity in infected cells. Analysis of RNA from infected cells indicated that CAT transcripts were present in multiple species of RNA. This unexpected result was found to reflect temporal shifts in promoter and poly(A) site usage during infection. Although the poly(A) site which forms part of the expression cassette was used extensively early in infection, most CAT transcripts synthesized at late times read through this promoter-proximal site and terminated at the distal site normally used for tk mRNA synthesis.
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PMID:Bovine herpesvirus 1 as a live virus vector for expression of foreign genes. 132 99

In order to compare the effect of the route of immunization on the efficacy of a modified live Aujeszky's disease (AD) vaccine, which had deletions in both thymidine kinase (TK-) and glycoprotein gIII genes (gpIII-), 20 six-week-old pigs were vaccinated by either the intramuscular (IM) (n = 10) or subcutaneous (SC) (n = 10) route. All the animals, including five non-vaccinated control animals, were challenged with virulent AD virus 22 days after vaccination. Four of five non-vaccinated animals died within 12 days after challenge. Although none of vaccinated animals died, three of animals in the SC group exhibited clinical signs, and average daily gains in the SC group were depressed. The animals in the IM group were not found to shed challenge virus, but those in the SC group shed the virus up to 9 days. Virus neutralizing antibody titers in the vaccinated animals were low or non-detectable by 21 days after vaccination. A glycoprotein gII (gpII) screening ELISA detected gpII antibody in all animals in the IM group. While, only 30% of animals in the SC group were positive by the same test. The results of this study indicate that TK-, gpIII modified live AD virus vaccine is effective against challenge with virulent AD virus; however, vaccination by the SC route reduced vaccine efficacy in comparison with IM route.
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PMID:Influence of vaccination route on the efficacy of Aujeszky's disease deletion-mutant vaccine. 132 80

The ability of 3'-fluoro-3'-deoxythymidine (FLT) to interfere with glycosylation was investigated in an experimental system, where the effects on the herpes simplex virus type 1-specified glycoprotein gC were determined. By adding FLT to HSV-infected cells after the peak of DNA synthesis, it was possible to segregate possible effects on nucleic acid metabolism from the effects on glycosylation of gC. It was found that FLT treatment of HSV-infected cells at concentrations of 20-500 micrograms/ml resulted in a significant increase in the electrophoretic mobility of gC, indicating a reduction of the amount of carbohydrates incorporated into gC. Lectin-binding assays demonstrated that the FLT treatment blocked addition of sialic acid to complex type N-linked glycans. The effects on glycosylation were observed in cells infected with an HSV mutant, deficient in thymidine kinase (TK), but not in cells infected with wild type virus. The cells infected with the wild type virus contained five times more total FLT metabolites than the cells infected with the TK-deficient mutant, whereas the latter cell type contained significantly higher amounts of unmetabolized FLT. This result indicates that FLT itself, and not a metabolite, was responsible for the effects on glycosylation.
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PMID:The HIV replication inhibitor 3'-fluoro-3'-deoxythymidine blocks sialylation of N-linked oligosaccharides. 133 99

Several conventional and genetically recombinant modified-live viral (MLV) vaccines are used to control pseudorabies virus infections (Aujeszky's disease, PRV) in swine. Differentiating vaccinal PRV (V-PRV) from wild PRV (WT-PRV) is important for herd health, regulatory and forensic purposes, and for studies of PRV latency and epidemiology. All PRV vaccines used currently contain glycoprotein I (gI) and/or thymidine kinase (TK) gene deletions, whereas WT-PRV typically contain intact gI and TK genes. Utilizing these differences we developed an effective but simple differential polymerase chain reaction (PCR) approach based upon the amplification of gI and TK gene polymorphisms. The primary immunoreactive epitope-encoding region of the gI gene and nearly the entire TK gene were amplified and analyzed using nested PCR procedures. TK and gI PCR products were cleaved with Sal I and Sac I, and Nco I restriction enzymes respectively. PCR product and restriction fragment length polymorphisms enabled most V-PRV to be clearly distinguished from each other, and all of them, as a group, clearly differentiated from typical WT-PRV. Mixtures of V-PRV and WT-PRV could be identified as such. The uncommon but occasional occurrence of atypical WT-PRV containing altered gI and/or TK genes indicates the need for interpretive caution, particularly if aberrant gene segment polymorphisms are observed. This rapid and precise molecular approach will facilitate regulatory monitoring, epidemiological investigations, diagnostic differentiation, purity testing and latency/recrudescence studies with the class of biologicals and offers a model for similar analyses of other MLV biologicals as well.
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PMID:Molecular analysis of pseudorabies viral vaccines and their rapid differentiation from wild-type isolates using DNA-amplified glycoprotein I and thymidine kinase gene segment polymorphisms. 133 75

We constructed a recombinant thymidine kinase-negative herpes simplex virus type 1 (HSV-1) that expressed the rotavirus major outer capsid glycoprotein, VP7. In the recombinant HSV-1, a promoter from the 5' noncoding region of the HSV-1 glycoprotein B locus regulated the expression of VP7 as a HSV-1 gamma 1 gene product. HSV-1-expressed VP7 resembled rotavirus-expressed VP7 in its SDS-PAGE mobility, high mannose-type glycosylation, disulfide bonding, perinuclear to cytoplasmic localization, intracellular retention, and reactivity with polyclonal antisera and nonneutralizing antibodies. Unlike rotavirus-expressed VP7, HSV-1-expressed VP7 lacked several neutralizing epitopes by immuno-histochemical staining and by ELISA. One neutralizing epitope identified on HSV-1-expressed VP7 by ELISA was masked by paraformaldehyde fixation of recombinant HSV-1- but not rotavirus-infected cells. Neutralizing epitopes were restored to HSV-1-expressed VP7 by coinfection of cells with the HSV-1 recombinant and a heterologous rotavirus that lack the neutralizing epitopes. The recovered neutralizing epitopes were detected on double-shelled rotavirus particles produced in the coinfected cells. This study indicates that the formation of several neutralizing epitopes on rotavirus VP7 requires interaction of VP7 with other rotavirus proteins. In addition, HSV-1 was a useful vector for studying the localization, processing, and antigenicity of an RNA virus glycoprotein.
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PMID:Neutralizing epitopes on herpes simplex virus-1-expressed rotavirus VP7 are dependent on coexpression of other rotavirus proteins. 137 Oct 25

Previous papers have reported that the syncytial mutant HSV-1(13)S11 carries three segregable syn mutations and exhibits its altered phenotype in four different cell lines, i.e. HEp-2, VERO, BHK and HEL both at 34 degrees C and 39 degrees C. Those studies have shown that one of three syncytial loci, designated Syn 5, is located in the Bam HI Q fragment spanning map units 0.296-0.317 of the prototype arrangement. Recombinants obtained from marker transfer experiments with donor BamHI Q fragment, have shown that locus Syn 5 is able to induce cell-to-cell fusion in VERO, BHK and HEL but not in HEp-2 cells. In this paper we have characterized the syn mutant HSV-1(13)S11 with regard to plaque morphology, synthesis of viral polypeptides and glycoproteins, thymidine kinase activity and physical map position of locus Syn 5 on the genome. Pertinent to the syn phenotype, earlier papers claimed that two different polypeptides, thymidine kinase (TK) and glycoprotein H (gH), whose genes map in BamHI Q, may be responsible for the fusion activity. Functional studies on the TK of the syn mutant HSV-1(13)S11 indicate that this polypeptide accumulates normally in infected cells and is a fully active enzyme. The other gene product, gH, has been studied with SDS-PAGE and in radioimmunoprecipitation (RIP) experiments using specific monoclonal antibodies. The results indicate that the amount of gH accumulation in the syn mutant-infected cells is greater than its parental strain. However, new marker transfer experiments described here located locus Syn 5 in 663 base pairs between SstI and EcoRI restriction endonuclease sites at the right end of the BamHI Q fragment, where TK gene overlaps in opposite orientation with UL 24 gene. Altogether these results indicate that the Syn 5 locus segregates from the gene specifying gH, to a region encompassing portions of the TK and UL 24 genes, and that the syn mutation does not affect the expression or activity of TK.
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PMID:Phenotypic and genotypic characterization of locus Syn 5 in herpes simplex virus 1. 164 2

Several vaccinia virus (VV)-varicella-zoster virus (VZV) recombinants expressing glycoprotein I (gpI) of VZV were isolated from the Prague strain of VV. One of these, v46, was inoculated intraperitoneally into mice. Groups of mice were bled 4 and 8 weeks later and their sera were examined for anti-VZV and anti-VV antibodies by ELISA. At 4 weeks, all mice inoculated with the three largest virus doses (10(7), 10(6) and 10(5) p.f.u.), and at 8 weeks all mice inoculated with the four highest virus doses (10(7), 10(6), 10(5), and 10(4) p.f.u.), had developed both anti-VV and anti-VZV antibodies. Antibodies were also detected in a high proportion of mice infected with lower doses of virus and in some instances VZV antibodies were present in the absence of VV antibodies. None of the animals inoculated in parallel with either a thymidine kinase-negative mutant of the original VV or diluent alone developed antibody reactive with VZV. The specificity of the reaction was assessed further by Western blotting using anti-gpI monoclonal antibodies as a positive control. Sera from animals immunized with v46 possessed antibody capable of neutralizing extracellular VZV in the presence of complement.
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PMID:Immunogenicity in mice of varicella-zoster virus glycoprotein I expressed by a vaccinia virus-varicella-zoster virus recombinant. 164 85

Vaccinia virus recombinants containing the sequences from herpes simplex virus type 1 (HSV-1) encoding the immediate early (IE)(alpha) proteins ICP4 and ICP0, under the control of a mutated vaccinia virus 11K late promoter, were constructed. A cDNA copy of the gene encoding ICPO and an ICP4-encoding genomic segment were each inserted into the vaccinia virus genome at the thymidine kinase (TK) locus by homologous recombination. Steady-state analyses revealed that RNAs homologous to the IE-0 and IE-4 sequences accumulated in cells infected by recombinants with the kinetics of a typical vaccinia late mRNA. Western blot analyses demonstrated that the expression level of both ICPO and ICP4, produced by the recombinant viruses, was comparable to that in HSV-1-infected cells at late times postinfection. Both proteins synthesized in cells infected by the recombinants were located in the nucleus as revealed by immunofluorescence. Although in vitro studies reveal that extracts from vaccinia-virus-infected cells lose the ability to transcribe genes that contain RNA polymerase II promoters (Puckett and Moss (1983), Cell 35, 441-448) both ICPO and ICP4 expressed by the recombinant viruses can transactivate plasmids containing a reporter gene driven by the promoters for the HSV-1 TK and glycoprotein C genes. Nuclear extracts prepared from cells infected with the vaccinia virus vector expressing ICP4 exhibited sequence-specific DNA-binding activity.
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PMID:Transactivation by herpes simplex virus proteins ICP4 and ICP0 in vaccinia virus infected cells. 165 5

The vaccine efficacy of a genetically engineered deletion mutant strain of pseudorabies virus, strain 783, was compared with that of the conventionally attenuated Bartha strain. Strain 783 has deletions in the genes coding for glycoprotein I and thymidine kinase. In experiment 1, which had a 3-month interval between vaccination and challenge exposure, strain 783 protected pigs significantly (P less than 0.05) better against virulent virus challenge exposure than did the Bartha strain. The growth of pigs vaccinated with strain 783 was not arrested, whereas that of pigs vaccinated with the Bartha strain was arrested for 7 days. Of 8 pigs given strain 783, 4 were fully protected against challenge exposure; none of the pigs given strain Bartha was fully protected. In experiment 2, which had a 3-week interval between vaccination and challenge exposure, the growth of pigs vaccinated with strain 783 was arrested for 3.5 days, whereas that of pigs vaccinated with the Bartha strain was arrested for 6 days. In experiment 3, pigs with moderate titer of maternal antibodies were vaccinated twice IM or once intranasally with either strain 783 or Bartha and were challenge-exposed 3 months after vaccination. Pigs given strain 783 twice IM were significantly (P less than 0.05) better protected than were the other pigs. They had growth arrest of only 6 days, compared with 9 days for pigs of other groups, and shed less virus after challenge exposure. Results of this study indicate that the vaccine based on the deletion mutant strain 783 is more efficacious than is the Bartha strain of pseudorabies virus.
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PMID:Efficacy of a pseudorabies virus vaccine based on deletion mutant strain 783 that does not express thymidine kinase and glycoprotein I. 165 33

Attenuated, gene-deletion mutants of pseudorabies virus (PRV) were tested for their ability to establish a reactivatable latent infection in pigs. The viruses (designated A, B, and C) were from each of three vaccines commercially available in the United States. Viruses A and C were similar in that they had genetically engineered gene deletions for thymidine kinase (TK) and glycoprotein X (gX); however, they had been prepared from genetically different parental strains. Virus B was TK positive, but had a naturally occurring gene deletion for glycoprotein I (gI). Four pigs were exposed oronasally to each of the viruses, and 10 weeks later they were treated with dexamethasone in an attempt to induce virus reactivation. All of the viruses replicated after initial exposure as evidenced by virus isolation from nasal swabs and the pigs' immune responses. Virus reactivation was subsequently induced by dexamethasone treatment in two of four pigs exposed to virus A. Notably, both pigs remained free of serum antibody for gX. Restriction endonuclease analysis and tests for TK activity and the presence of gX indicated that reactivated virus was similar, if not identical, to virus A used to establish latent infection. Virus shedding after dexamethasone treatment was not identified for either of the other pigs exposed to virus A nor for any of the pigs exposed to viruses B or C. The results indicated that attenuated, TK-negative PRV can establish a reactivatable, latent infection in pigs.
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PMID:Virus reactivation in pigs latently infected with a thymidine kinase negative vaccine strain of pseudorabies virus. 165 20


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