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Biomedical subjects

E Geissler

Publications and source records attributed to E Geissler.

At least 37 records · Page 2Linked to original sources
PubMed1986

Studies on the SV40-like papovavirus SV40-GBM. III. Propagation at low multiplicities of infection in various human cell lines.

At low multiplicity several human cell lines supported the lytic infection with SV40-GBM better than that with the wild type SV40. The efficiency of viral DNA replication differed in the cell lines used suggesting that specific host cell factors may determine the rate of viral DNA synthesis. Furthermore, the emergence of different DNA defects during propagation of the virus indicates that host cell factors in question might also influence the composition of the viral DNA population.

Cell Line↗
PubMed1983

Virus-induced gene mutations of eukaryotic cells.

Most animal viruses studied so far induce chromosomal aberrations. In addition, adenoviruses, papovaviruses, and retroviruses are known to induce gene mutations like mutagenic bacteriophages. At least in one case studied retrovirus induced mutagenesis involves gene and/or scripton splitting analogous to the mutagenic mechanism of action of mutatorphage Mu and other movable DNA elements. On the contrary, several results obtained by independent means indicate that Simian virus 40, a papovavirus, does not act by splitting the affected gene but presumably by generation of base pair substitutions or of other minor DNA damages leading to amino acid substitutions. The mechanisms involved are still unknown. There a some hints, however, that these mechanisms might have some step(s) in common with processes leading to malignancy. In fact those viruses proved unequivocally so far to be capable of inducing gene mutations are oncogenic viruses.

Adenoviridae↗
PubMed1983

Studies on the SV40-like papovavirus SV40-GBM. II. Molecular cloning in Escherichia coli of variant DNA molecules from glioblastoma-derived virus.

The complete DNA genomes of the SV40-like GBM virus (GBM1), isolated from a human glioblastoma multiforme, and of two discrete classes of GBM DNA molecules that appear following three passages in CV-1 monkey cells at low multiplicities (GBM3-H and GBM3-L), were cloned in Escherichia coli using plasmid vector pBR322. The cloned viral DNAs were characterized (i) by digestion of the chimeric plasmid DNAs with various restriction enzymes followed by comparison of their electrophoretic mobilities in agarose with that of similarly digested uncloned DNA, (ii) by hybridization of digested chimeric plasmid DNAs to 32P-labeled uncloned GBM DNA, and (iii) by electron microscopy. In restriction enzyme analysis the cloned GBM DNAs showed the same cleavage pattern as the uncloned DNAs, indicating that no major insertions or deletions were present. The electrophoretic data were confirmed by electron microscopic heteroduplex analysis.

Cloning, Molecular↗
PubMed1983

Studies on the SV40-like papovavirus SV40-GBM. I. Genomic analysis by restriction endonucleases and electron microscopy after propagation in CV-1 monkey cells.

Infection of CV-1 monkey cells with SV40-GBM, a papovavirus isolated from a human glioblastoma multiforme, resulted in the appearance of defective viral DNA molecules. In contrast to SV40 wild-type, two main types of variant DNA molecules could be found after three viral passages at multiplicities of infection of about 10. The molecules of one variant DNA (GBM3-L) were about 19% shorter than the GBM3-H DNA molecules and the DNA of the original GBM isolate, as demonstrated by electron microscopy. Restriction enzyme analysis revealed that GBM3-L DNA had lost both the EcoRI and the HpaII cleavage sites which are located in the late viral genome region. Furthermore, SV40 GBM3-L did not possess the two PvuII sites which are located in the late genome region, and a portion of the GBM3-H and GBM3-L DNA molecules had lost the unique KpnI site. Heteroduplex analysis verified that the rearrangements in the GBM3-L DNA are located only in the late region of this DNA. The possible differences between SV40 wild-type and SV40-GBM are discussed on the basis of these results.

Animals↗
PubMed1983

In vitro transformation and mutation of Chinese hamster cells by different SV40 nucleoprotein complexes.

SV40 minichromosomes (MCH) either isolated from SV40 infected CV-I monkey cells (native MCH) or reconstituted in vitro from viral DNA and the H1 depleted calf thymus histone fraction could transform and mutate Chinese hamster (CH) cells in vitro. Whereas reconstituted MCH transformed and mutated CH cells with about the same efficiency as purified SV40 DNA, approximately 10-200-fold increase in the transforming activity had been demonstrated for native MCH. All transformed cell colonies and a major part of the isolated mutant cell clones recovered after inoculation of CH cells with SV40 MHC expressed the SV40 T antigen. Addition of H1 to both purified SV40 DNA and reconstituted MHC drastically diminished the transforming capacities of both agents. Possible reason(s) for the inhibition effect of H1 histone is discussed.

Animals↗
PubMed1983

Immortalization of human Lesch-Nyhan-fibroblasts following infection with Simian virus 40.

Skin fibroblasts of three Lesch-Nyhan patients were successfully transformed to unrestricted growth by Simian virus 40. The transformed character of isolated clones was confirmed by their epitheloid growth in medium containing low concentration of serum, by hyperdiploid karyotype patterns, by detection of SV40 T-antigen, by their growth in soft agar and by the proliferation of cells in vitro up to 200 passages hitherto.

Animals↗
PubMed1983

Evolutionary relationships between papovaviruses and their hosts.

The papovaviridae family consists of two genera, the papillomaviruses (PV) and the polyomaviruses (Py-V). Both genera are distinguished by morphological (larger sizes of the PV) and several biological characteristics. The genomes of either of the two genera share highly conserved DNA regions and a common antigenic determinant, located in their major capsid polypeptides. On the basis of these data an evolutionary relationship among the members of PV and Py-V, respectively, has been suggested. No homology has been found for either DNA- or protein sequences between PV and Py-V and the question of a common ancestor for both viral genera remains open. We have started to characterize the genome of a papilloma producing papovavirus of the Syrian hamster (HaPV). Most of the known biological characteristics of the HaPV suggest it should be classified as a papilloma-like virus. However, the molecular weight of about 3.5 X 10(6) daltons found for the circular duplex DNA lies within the range given for SV 40 and polyoma virus (Py). Analysis of the HaPV genome by cleavage with 21 different restriction endonucleases, location of specific binding sites of phage T 4 gene 32 protein and E. coli RNA polymerase on the viral DNA demonstrated that the HaPV differed distinctly from all other currently known papovaviruses. The HaPV genome was also analyzed by filter hybridization and electron microscopy under conditions of varied stringency for nucleotide sequence homology with the genomes of different papovaviruses of both genera. Whereas no homologous DNA regions could be found between the genomes of HaPV and the human PV types 1 and 4, only under nonstringent conditions (Tm-43 degrees C) stable hybrids were formed between HaPV-, SV 40- and the DNA of a PV isolated from Mastomys natalensis (MnPV). On the other hand extensive homology was detected between the genomes of HaPV and Py even under stringent hybridization conditions (Tm-28 degrees C). The homologous DNA segments mapped on the Py and partially on the SV 40 genome were found to be the most strongly conserved DNA regions among the Py-V genus. These results are discussed with respect to a classification of the HaPV within the papovaviridae family.

Animals↗
PubMed1983

SV40 and SV40-like viruses as possible risk factors.

SV 40 and its derivatives are highly suspicious of being risk factors involved in the development of certain intracranial tumors. Therefore further activities should be undertaken to prove or to disregard this suspicion especially with respect to the world-wide man-made dissemination of SV 40 among the human population.

Adolescent↗
PubMed1983

Are transforming and mutagenic activities of oncogenic papovaviruses correlated?

A number of results obtained recently have shown that SV40-induced mutation and transformation of mammalian cells cultivated in vitro are related in some respect. Experiments were undertaken in order to get further information on the mode of mutagenic action of papovaviruses and further evidence of correlations existing between the mutagenic and transforming viral activities. DNA from the oncogenic hamster papovavirus HaPV was found to be mutagenic for at least three different resistance markers. In the hamster cell lines which were used HaPV DNA produced a higher yield of mutants than SV40 DNA for both the azaguanine and the aminopterin resistance marker. Cellular clones carrying a SV40-induced mutation in a specific locus were found to harbour viral genetic material and to exhibit a genetic instability of other loci. Also, cell lines characterized by their SV40-transformed state did exhibit such genetic instability. These results and results of other authors are discussed with respect to the correlations between oncogenic virus-induced mutation and transformation.

Animals↗
PubMed1983

Quantitative determination of papovavirus IgG antibodies in sera from cancer patients, labworkers and several groups of control persons by enzyme-linked immunosorbent assay (ELISA).

An enzyme-linked immunosorbent assay (ELISA) for detection of specific IgG antibodies against the capsid antigen of SV40 and SV40-GBM is described. We have determined the presence of SV40 and SV40-GBM IgG antibodies, respectively, in sera of labworkers who are in intensive or rare contact to SV40, in sera of tumor patients as well as in sera of different control persons. In 13% of the sera of the control group antibodies against SV40 were found, when the persons were born 1962 or later. They received SV40-free poliomyelitis vaccine. On the other hand 24% of the sera were positive when the people were born between 1959-61 and probably received SV40-contaminated poliomyelitis vaccine. A similar percentage of positive sera (21-32%) were found in cancer patients suffering on different tumors. Also 29% of the sera of labworkers, born before 1955 and with rare contact to SV40 reacted positive. However, 55% of the sera of labworkers had positive sera when they were in intensive contact to SV40. The results presented and discussed in the light of SV40 as a possible risk factor for the human population.

Adult↗
PubMed1983

The efficiency of genetic transformation of mammalian cells by transfection and microinjection depends on the transferred gene.

The efficiency of genetic transformation of mammalian cells was analysed with respect to the kind of the transferred gene and the selective system. Plasmids pAGO and pAG60 harboring the thymidine kinase gene of Herpes simplex virus type 1 and the bacterial neomycin resistance gene, respectively, were compared concerning their ability to transform mouse Ltk-aprt- cells. Using the calcium phosphate technique the neomycin resistance gene transformed at least ten times more efficiently than the thymidine kinase gene (3 X 10(-3) versus 2 X 10(-4] whereas the difference is even more impressive following microinjection of the plasmids into the nuclei (2 X 10(-1) versus 2.5 X 10(-3]. The neomycin system also proved to be more effective in secondary gene transfer experiments and, thus, seems to be the most convenient marker for cotransfer experiments.

Animals↗
PubMed1982

The DNA tumor virus SV 40 induces gene mutations in human cells. Reversion of HPRT deficiency.

The mutagenic effect of papovavirus SV40 on human cells could be demonstrated by reversion of HPRT deficiency in Lesch-Nyhan fibroblasts transformed by the virus. SV40 seems to induce different gene mutations in individually selected cell clones, as was clearly shown by the respective HPRT enzyme properties. The consequences of our results for use of SV40-derived vectors in gene substitution experiments are discussed.

Cell Transformation, Viral↗
PubMed1981

Further studies on a temperature-sensitive mutant of Escherichia coli with defective repair capacity.

A temperature-sensitive mutant of E. coli, WG24, was studied with respect to its sensitivity to photodynamic action, its capacity to perform host controlled reactivation, and its sensitivity to transduction at elevated temperatures. Mutant cells are much more sensitive than wild type cells to photodynamic action by thiopyronine and visible light at elevated temperatures. As well defined rec mutants, WG24 cells are less able to reactivate UV irradiated lambda c phages at elevated temperatures, while their ability to repair T1 phages is less impaired. Mutant cells cannot be transduced to T6 resistance at a detectable rate at elevated temperature. It is concluded, therefore, that some rec gene carries a ts mutation in this mutant.

Coliphages↗
PubMed1981

Influence of superinfection on the photoreversible phase of UV induced lysogenic bacteria.

1. Lysogenic induction by UV light can be reversed by photoreactivation. UV-treated E. coli K12 (lambda)+ uvr+ and uvr cells are sensitive to photoreactivation for a given time after irradiation. This sensitivity suddenly disappears at the end of this time. 2. The photoreversible period of UV induction is more than twice as long in uvr cells as it is in uvr+ cells. 3. The photoreversible period can be reduced by superinfection with lambda c mutants after irradiation. This effect is positively correlated with the multiplicity of superinfection. Such a reduction does not occur when superinfection is carried out with wild-type phages or with heteroimmune derivatives. 4. We concluded that during the photoreversible period of UV induction oligonucleotides are excised or synthesized and gaps are formed during excision repair and post replication repair of UV damage; these might react with E. coli recA protein thereby activating it to induce its own synthesis, to cleave phage repressors and to exert its other SOS functions.

Bacteriophage lambda↗
PubMed1981

HGPRT structural gene mutation in Lesch-Nyhan-syndrome as indicated by antigenic activity and reversion of the enzyme deficiency.

For three patients with the Lesch-Nyhan syndrome the existence of normal amounts of catalytically inactive hypoxanthine-guanine phosphoribosyltransferase (HGPRT) protein was demonstrated by using antibodies against the normal enzyme subunits. The lack of enzyme activity is reverted in virus transformed cells. Individual revertant cell clones contain different HGPRT enzymes as demonstrated here by isoelectric focusing. The data strongly support the idea of a structural gene mutation as the cause of enzyme deficiency in the Lesch-Nyhan syndrome.

Cross Reactions↗