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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

The temperature-sensitive (ts), thymidine kinase-deficient (TK-) mutant designated ZHtsTK- strain, of Aujeszky's disease virus (ADV) was isolated from a virulent strain with the treatments using 5-bromodeoxyuridine and arabinosylthymine. The ZHtsTK- strain was easily distinguished from the other virulent ADV strains by plaque size on HmLu-1 and chicken embryo fibroblast cells and by restriction endonuclease analyses using Bam HI, Sal I and Kpn I. The ZHtsTK- strain was avirulent for mice, guinea pigs and rabbits, and produced neutralizing antibodies to ADV in these animals. The rabbits inoculated with the ZHtsTK- strain did not shed detectable amounts of virus after dexamethasone treatment. The ZHtsTK- strain was also avirulent for 5-day-old piglets and did not cause disease. No virus was detected from the piglets inoculated intramuscularly in the nasal swabs or the tissues examined on postinoculation day 9. These findings presented here suggested that there is a significant correlation between pathogenicity and properties such as ts and TK-, and the combination of ts and TK- properties plays a much larger role in reducing virulence for animals.
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PMID:Avirulent ts and thymidine kinase-deficient mutant of Aujeszky's disease virus. 165 12

A clinical isolate, designated 145, of herpes simplex virus (HSV) had type 1 characteristics as determined by monoclonal antibody immunofluorescence, heat stability of viral thymidine kinase (TK), BamHI restriction endonuclease pattern, and absence of the HSV-2-specific 38-kD protein. However, instead of being sensitive to E-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) like HSV-1, isolate 145 displayed a resistance pattern like HSV-2 to the drug as determined by viral replication and viral DNA synthesis. Because BVDU is activated by viral TK phosphorylation, we cloned the TK-containing DNA region from isolate 145 and compared it by restriction mapping using several endonucleases to similar regions of HSV-1 and HSV-2. In each instance, the patterns for HSV-1 and isolate 145 were identical to each other, but distinct from the patterns for the corresponding region of HSV-2, suggesting that the genome TK region of isolate 145 was HSV-1-like.
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PMID:Herpes simplex virus type 1 that exhibits herpes simplex virus type 2 sensitivity to (E)-5-(2-bromovinyl)-2'-deoxyuridine. 165 22

Bovine herpes mammillitis virus (BHMV) codes for a thymidine kinase (Tk), the gene for which is located in a 2.6 kb SalI restriction endonuclease fragment with a map unit of 0.2-0.32. This particular DNA fragment can transfect LTk-mouse cells and convert them to Tk+. The gene position of BHMV Tk would suggest another homologous gene map position for BHMV and herpes simplex virus (HSV).
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PMID:Bovine herpes mammalitis virus thymidine kinase gene. 197 81

A DNA fragment from fowlpox virus cloned on a plasmid vector was modified to contain foreign DNA inserts within an intergenic region. In a first step, a 32-base-pair intergenic region from the fowlpox virus genome corresponding to the position of the thymidine kinase locus in the vaccinia virus genome was enlarged to 55 base pairs by site-directed mutagenesis. A unique restriction endonuclease site introduced upstream of the intergenic region was then used to insert various foreign DNA fragments. The lacZ gene encoding beta-galactosidase and the measles virus gene encoding the fusion protein were positioned downstream of two vaccinia virus p7.5 promoter elements in either a direct repeat or inverted repeat orientation. Foreign DNA inserts contained within the fowlpox virus sequence were transferred to the viral genome by homologous recombination occurring in cells infected with a fowlpox virus temperature-sensitive mutant and transfected with both wild-type viral DNA and plasmid DNA. Recombinant viruses were selected for the expression of beta-galactosidase activity by screening for blue plaques in the presence of a chromogenic substrate. Stable recombinants expressing both the lacZ gene and the unselected measles gene were obtained when the p7.5 promoter was present as an inverted repeat. However, when the p7.5 promoter was in the direct repeat orientation, viral recombinants which initially expressed both gene inserts readily deleted the lacZ gene flanked by the promoter repeat. The methods described enable precise insertion and deletion of foreign genes in the fowlpox virus genome and could be applied to other intergenic regions of the same virus as well as other poxviruses.
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PMID:Construction of fowlpox virus vectors with intergenic insertions: expression of the beta-galactosidase gene and the measles virus fusion gene. 215 22

A case is reported of relapsing fatal meningoencephalitis caused by a neurovirulent thymidine kinase-positive (TK+) type 2 herpes simplex virus (HSV) that developed thymidine kinase deficiency (TK-) during intravenous acyclovir therapy. A patient with AIDS was admitted for acyclovir treatment of a persistent perirectal herpetic ulcer. He subsequently developed meningoencephalitis. A TK+ type 2 HSV was isolated from a brain biopsy specimen. A progressive and fatal relapse occurred, and a TK- type 2 HSV was isolated from his cerebrospinal fluid. Restriction endonuclease analysis of viral DNA from perianal, brain, and cerebrospinal fluid isolates were similar, suggesting that they were the same viral strain. Animal virulence studies indicated significant cutaneous virulence in immunocompromised mice models for the TK- isolates. This case is notable because TK- HSV have, in the past, lacked neurovirulence and because acyclovir resistance developed during therapy and caused the patient's death.
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PMID:Herpes simplex virus type 2 meningoencephalitis resistant to acyclovir in a patient with AIDS. 215 46

On the basis of their restriction endonuclease digestion patterns, four Australian bovine herpesvirus type 1 (BHV-1) isolates were classified as belonging to the BHV-1.2a subtypes. The thymidine kinase (TK) genes of all four BHV-1.2a isolates were located on a 3.5 kb SalI restriction fragment. This is in contrast to North American and European BHV-1.1 isolates whose TK genes are contained on a 2.6 to 2.8 kb SalI fragment. The restriction fragments containing the TK genes were cloned into phagemid vectors and their sequences determined using the dideoxynucleotide chain termination method. The BHV-1.2a isolates possessed identical TK gene sequences, which differed from previously published TK sequences for the LA and 6660 BHV-1.1 strains. In addition to five single base alterations, there were six separate base insertions which resulted in two major frameshifts which spanned an area of 72 amino acids or 20% of the expressed TK gene product. The predicted amino acid sequence exhibited a higher degree of similarity to other herpesvirus TKs, suggesting that previously published TK gene sequences may have been incorrect. The present nucleotide sequence and corresponding amino acid composition reinforces previous observations concerning regions of herpesvirus TK amino acid conservation and should assist in future studies into the evolution and functional domains of herpesvirus TKs.
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PMID:The location and nucleotide sequence of the thymidine kinase gene of bovine herpesvirus type 1.2. 217 55

Isolation and general properties of 3'-5' exonucleases I and II (EC 3.1.4.26), which are specific to single-stranded DNA, are described. Such enzymes, being components of replication complexes, could correct replication errors. Homogeneous exonucleases I and II consist of a single subunit with molecular mass of 50 and 40 kDa, respectively. These enzymes are located preferentially in the nuclear membrane and chromatin. They form complexes with nuclear DNA polymerases and some other proteins and are not observed practically in a free state. Molecular masses of the complexes amount from 70 to 1.500 kDa. The complexes dissociate as a result of solution hydrophobization and can be reconstituted after the decrease of hydrophobization. The heavy membrane complex form of 3'----5' exonuclease I manifests enzymatic activities of DNA polymerase alpha (EC 2.7.7.7), non-specific nucleoside triphosphatase (EC 3.1.3.2), nucleotidase (EC 3.1.3.31) and faint activity of endonuclease (EC 3.1.4.5). Complexes under study do not display activity of thymidine kinase (EC 2.7.1.21), marker protein of replitase, neither in G0 nor in S-period.
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PMID:[Homogeneous 3'----5'-exonucleases and their multienzyme complexes from the rat liver]. 234 19

Plasmids that replicate autonomously in mouse L cells were constructed by inserting random genomic DNA fragments from Ltk- cells into a plasmid containing the HSV-1 thymidine kinase gene with a truncated low-efficiency promoter. HAT resistance was used as a selective marker. The presence of free plasmids in the DNA of transformants was demonstrated by hybridization with a specific plasmid probe, by electron microscopic visualization of circular DNA, and by recovering these plasmids by E. coli transformation. Nineteen different DNA fragments were isolated. They were characterized as murine autonomously replicating sequences by Mbol restriction endonuclease sensitivity, by bromodeoxyuridine substitution, by copy number determination, and by segregation analysis. Sequence analysis of the inserts of nine plasmids revealed a conserved element of 12 bp (CTCATGAGAGGCCAA) in five out of nine autonomously replicating sequences.
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PMID:Murine genomic DNA sequences replicating autonomously in mouse L cells. 291 71

The location of nucleotide sequences within the bovid herpesvirus 1 (BHV-2) genome homologous to herpes simplex virus 1 (HSV-1) DNA were investigated. BHV-2 DNA was digested with restriction endonucleases and blotted to nitrocellulose paper. The blots were then probed with plasmids containing HSV-1 genes for thymidine kinase (TK), the major DNA binding protein (ICP8), the major capsid protein (VP5) and genes for HSV-1 glycoproteins gB, gD, and gC. Except for HSV-1 gC, each HSV-1 gene tested hybridized to BHV-2 nucleotide sequences that were located either on both sides of a restriction endonuclease cleavage site, within a small restriction endonuclease fragment, or to an area common to two overlapping restriction fragments. Thus, we were able to localize BHV-2 nucleotide sequences homologous to the HSV-1 ICP8 gene between 0.38 and 0.41 map units (m.u.), and BHV-2 nucleotide sequences homologous to the HSV-1 VP5 gene between 0.24 and 0.27 m.u. In addition, BHV-2 nucleotide sequences homologous to HSV-1 genes for TK, gB and gD were found to lie on both sides of restriction endonuclease cleavage sites at 0.30, 0.35, and 0.94 m.u., respectively.
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PMID:Genomic location of bovid herpesvirus type 2 nucleotide sequences homologous to five herpes simplex virus type 1 genes. 284 79


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