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Biomedical subjects

B Francke

Publications and source records attributed to B Francke.

At least 19 recordsLinked to original sources
PubMed1984

The interaction of a topoisomerase-like enzyme from herpes simplex virus type 1-infected cells with non-viral circular DNA.

An enzyme activity from herpes simplex virus type 1 (HSV-1)-infected baby hamster kidney cells has been identified which generates large networks of pBR322 DNA from a monomeric DNA substrate. Extracts derived from cells infected at the non-permissive temperature, with the early regulatory mutants of HSV-1, tsK and tsB2, did not contain activity, suggesting that the enzyme is virus-induced and may be virus-specific. The enzyme is similar to the DNA topoisomerases in that network formation was dependent upon the presence of Mg2+ and a DNA condensing agent, and ATP was not required. Following digestion with EcoRI, the networks could be resolved to a single, linear, monomeric species of pBR322 DNA.

Animals↗
PubMed1983

Induction of nuclear deoxyribopyrimidine triphosphatase and sensitivity of clinical isolates of herpes simplex virus to (E)-5-(2-bromovinyl)-2'-deoxyuridine.

In a blind study, 21 clinical isolates of herpes simplex virus which had been typed using differential growth on guinea pig embryo versus chicken embryo cells were tested for the presence of the viral deoxyribopyrimidine triphosphatase. In all isolates of type 1, the triphosphatase was present in the nuclei of the infected cells, while none of the HSV-2 isolates induced a nuclear enzyme. In all isolates there was a complete correlation between the presence of nuclear deoxyribopyrimidine triphosphatase and sensitivity to 0.7 microgram/ml of E-5-(2-bromovinyl)-2'-deoxyuridine. The study suggests that the type-specific distribution of the triphosphatase is of general validity, including clinical isolates of herpes simplex virus, and could be used as a type-specific enzyme marker.

Animals↗
PubMed1983

Replication of herpes simplex virus type 1 on hydroxyurea-resistant baby hamster kidney cells.

Hydroxyurea-resistant (HUr) baby hamster kidney cells were isolated, subcloned, and characterized. One clonal line, which contained elevated levels of ribonucleotide reductase, lost its HU resistance during passage in the absence of the inhibitor, whereas another clonal line was stably resistant. The replication of herpes simplex virus type 1 on these cells was compared with that of the parvovirus minute virus of mice. Herpes simplex virus type 1 was found to be as sensitive to HU on both lines of HUr baby hamster kidney cells as it was on parental (HU-sensitive) cells, whereas parvovirus replication was about eight times more resistant on HUr baby hamster kidney cells compared with the parental cells. The results suggest that herpes simplex virus type 1 cannot use the cellular reductase and may code for its own.

Animals↗
PubMed1982

Organization of herpes simplex virus type 1 deoxyribonucleic acid during replication probed in living cells with 4,5',8-trimethylpsoralen.

The structure of herpes simplex virus type 1 (HSV-1) DNA in the nuclei of living infected cells was studied with the DNA photoaffinity probe 4,5',8-trimethylpsoralen. The rate of photobinding to HSV-1 DNA was compared to that of a suitable internal control at different times during infection. The rates of photobinding to DNA packaged in virions, capsids, and prereplicative and postreplicative DNA were characteristically different. By 4 h after infection, after the initiation of DNA replication, the rate of photobinding to HSV-1 DNA increased 4 times relative to the rate of binding to the host DNA. The enhanced rate of photobinding to HSV-1 DNA was maintained at all later times during infection and was not affected when frequent single-strand breaks were introduced in HSV-1 DNA by gamma irradiation of infected cells. The results suggest that the bulk of the replicating herpes DNA is free of torsional tension and that the differing rates of photobinding are attributable to changes in accessibility of the HSV-1 DNA. The results are compatible with previous proposals, based on in vitro studies, that intranuclear HSV-1 DNA is primarily free of nucleosomal organization and suggest that there are few, if any, unrestrained DNA supercoils averaged over the entire HSV-1 genome.

Affinity Labels↗
PubMed1982

Control of expression of the herpes simplex virus-induced deoxypyrimidine triphosphatase in cells infected with mutants of herpes simplex virus types 1 and 2 and intertypic recombinants.

Infection of cells with herpes simplex virus type 1 (HSV-1) induces high levels of deoxypyrimidine triphosphatase. The majority of the enzyme activity is found in infected cell nuclei. A similar activity is induced by HSV type 2 (HSV-2) which, in contrast to the HSV-1 enzyme, fractionates to more than 99% in the soluble cytoplasmic extract. Of a series of temperature-sensitive mutants of HSV-1 studied, only the immediate-early mutants in complementation group 1-2 (strain 17 mutants tsD and tsK and strain KOS mutant tsB2) induced reduced levels of triphosphatase at nonpermissive temperature. Of a series of temperature-sensitive mutants of HSV-2 strain HG52, ts9 and ts13 failed to induce wild-type levels of the enzyme at nonpermissive temperature; ts9 was the most defective mutant with regard to triphosphatase expression of both herpes simplex virus serotypes. After shift-up from permissive to nonpermissive temperature, triphosphatase activity in cells infected with ts9 decreased rapidly, whereas all other mutants continued to exhibit enzyme levels comparable with controls kept at the permissive temperature. The type 1-specific nuclear expression of the triphosphatase was mapped physically by the use of HSV-1 x HSV-2 intertypic recombinants, based on enzyme levels different by more than two orders of magnitude found in nuclei of HSV-1- and HSV-2-infected cells. The locus for the type-specific expression maps between 0.67 and 0.68 fractional length on the HSV genome.

Animals↗
PubMed1981

Requirement of the human chromosome 11 long arm for replication of herpes simplex virus type 1 in nonpermissive Chinese hamster x human diploid fibroblast hybrids.

Somatic cell hybrids between Chinese hamster (CH) lung cells (V79/380-6), nonpermissive for productive infection by herpes simplex type 1 (HSV-1), and permissive human diploid cells support productive HSV-1 infection as long as they retain human chromosome 11. Human chromosome 3 has been reported to complement nonpermissivity in (CH) Don cells (1). Intraspecies hybrids between Don/a3 and V79/380-6 cells, however, did not support HSV-1 replication, indicating lack of complementation. The block in both nonpermissive CH cell lines was determined to involve a step beyond replication of the parental viral DNA. In cell hybrids between nonpermissive Don/a23 cells and human fibroblasts containing a t(11;15) (p11;p12) translocation, HSV-1 production was dependent solely on the presence of either human chromosome 11 or the der(11) (p11 leads to qter) translocation product containing the long arm of chromosome 11. Chromosome 3 was excluded by a discordancy rate of 59%. We conclude that the long arm of human chromosome 11 carries one or more genes coding for host functions necessary for the production of progeny HSV-1 DNA.

Animals↗
PubMed1981

Effect of novobiocin and other DNA gyrase inhibitors on virus replication and DNA synthesis in herpes simplex virus type 1-infected BHK cells.

The four known inhibitors of the bacterial DNA gyrase (nalidixic acid, oxolinic acid, novobiocin and coumermycin A) were investigated with respect to their effect on the growth of uninfected BHK cells and the yield of virus from herpes simplex virus type 1 (HSV-1)-infected BHK cells. High concentrations of nalidixic acid and oxolinic acid (about 10 mM) were needed for 50% inhibition of cellular and viral multiplication with less than fourfold preferential inhibition of virus over cell growth. Novobiocin and coumermycin were effective at lower molar concentrations and the amount needed for 50% inhibition was 10-fold higher for cell growth than for virus yield. At 5 x 10(-4) M, novobiocin inhibited DNA synthesis in uninfected cells to approx. 20% of non-treated controls, while virus DNA in infected cells was almost completely inhibited (approx. 1% of controls). Residual cellular DNA synthesis in infected cells was rather insensitive (approx. 90% of controls) to this concentration of novobiocin.

Aminocoumarins↗
PubMed1980

Deoxyribopyrimidine triphosphatase activity specific for cells infected with herpes simplex virus type 1.

Nuclei from baby hamster kidney cells infected with herpes simplex virus type 1 contain a virus-specific deoxyribonucleoside triphosphate degrading activity. The reaction proceeds at 4 degrees C and can thus be distinguished from host enzymes. Under these conditions the enzyme is specific for deoxyribopyrimide triphosphates and catalyzes pyrophosphate cleavage to produce the monophosphates, dUTP being the best substrate followed by dCTP and dTTP. The appearance of the activity after infection parallels that of viral DNA-synthesis-related functions. Of a series of eight temperature-sensitive mutants tested, two (tsD and tsK) exhibit significantly decreased triphosphatase levels after infection at nonpermissive temperature, whereas a viral deoxypyrimidine kinase-deficient mutant induced wild-type levels.

Animals↗
PubMed1978

Cell-free synthesis of herpes simplex virus DNA: the influence of polyamines.

The effect of polyamines on cell-free DNA synthesis of herpes simplex virus DNA in two different systems is investigated. Purified nuclei from infected cells are devoid of measurable amounts of putrescine, spermidine, and spermine, while an unfractionated lysate contains the polyamines at close to their respective cellular concentrations. Spermine, 0.3 mM, and 0.5 mM spermidine, when added to the nuclear system, decrease the extent of viral DNA synthesis to the level found in the lysate system, the size of the cell-free viral DNA product is increased, and a specific inhibition of repair-type DNA synthesis is observed. These effects of the polyamines occur only in the presence of ATP and not the other three ribonucleoside triphosphates.

Cell Line↗
PubMed1978

Alkaline DNase activity in cells infected with a temperature-sensitive mutant of herpes simplex virus type 2.

BHK cells infected with the temperature-sensitive mutant ts13 of herpes simplex virus type 2 at a nonpermissive temperature lack the alkaline nuclease activity, which is induced by the mutant at a permissive temperature and by wild-type virus at either temperature. For ts13, enzyme activity could be induced by a temperature shift to permissive conditions, but not in the presence of cycloheximide. After a shift from permissive to nonpermissive conditions in the presence of cycloheximide, the activity was stable in wild-type, but not in mutant-infected, cells. After extensive purification, the wild-type nuclease was fourfold more heat stable in the presence of substrate than was the mutant enzyme. Mixtures of both purified enzymes showed the predicted intermediate stabilities. The results strongly suggest that the enzyme is virus coded and that the mutant possesses a lesion in the structural gene of the enzyme.

Cell Line↗
PubMed1978

Viral DNA synthesis in cells infected with temperature-sensitive mutants of herpes simplex virus type 1.

Temperature-sensitive mutants of herpes simplex virus type 1 representing eight DNA-negative complementation groups were grouped into the following three categories based on the viral DNA synthesis patterns after shift-up from the permissive to the nonpermissive temperature and after shift-down from the nonpermissive to the permissive temperature in the presence and absence of inhibitors of RNA and protein synthesis. (i) Viral DNA synthesis was inhibited after shift-up in cells infected with tsB, tsH, and tsJ. After shift-down, tsB- and tsH-infected cells synthesized viral DNA in the absence of de novo RNA and protein synthesis whereas tsJ-infected cells synthesized no viral DNA in the absence of protein synthesis. The B, H, and J proteins appear to be continuously required for the synthesis of viral DNA. (ii) Viral DNA synthesis continued after shift-up in cells infected with tsD and tsK whereas no viral DNA was synthesized after shift-down in the absence of RNA and protein synthesis. Mutants tsD and tsK appear to be defective in early regulatory functions. (iii) Cells infected with tsL, tsS, and tsU synthesized viral DNA after shift-up and after shift-down in the absence of RNA and protein synthesis. The functions of the L, S, and U proteins cannot yet be determined.

Cell Line↗