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Biomedical subjects

K O Fresen

Publications and source records attributed to K O Fresen.

11 recordsLinked to original sources
PubMed1985

Transformation by Epstein-Barr virus requires DNA sequences in the region of BamHI fragments Y and H.

Eight independent recombinant Epstein-Barr virus genomes, each of which was a transforming strain, were made by superinfecting cell lines containing Epstein-Barr virus DNA (Raji or B95-8 strain) with a nontransforming virus (P3HR1 strain). A knowledge of the constitution of each transforming recombinant allowed the localization of the defect in the genome of the nontransforming parent to a 12-megadalton sequence within the EcoRI A fragment. Within this region, the nontransforming virus has a deletion of the BamHI Y fragment and about half of the sequences in the adjacent BamHI H fragment. The present data suggest that this deletion is responsible for the nontransforming phenotype. Furthermore, mapping a deletion in one of the recombinant genomes allowed the conclusion that a sequence (comprising about 20% of the Epstein-Barr virus genome) from the center of BamHI-D to BamHI-I' is not necessary for the maintenance of transformation by Epstein-Barr virus.

Base Sequence↗
PubMed1978

Recovery of transforming EBV from non-producer cells after superinfection with non-transforming P3HR-1 EBV.

Cells of the Raji and NC37 lines can be induced by chemical inducers, such as BrdUrd and IdUrd, or the tumor-promoter TPA to EA-expression only, but do not reveal any VCA synthesis. After superinfection by nontransforming P3HR-1 EBV, however, a varying percentage of the cell population shows VCA synthesis and releases infectious viral particles. The recovered virus differs biologically from P3HR-1 EBV since it transforms human umbilical cord blood lymphocytes into EBNA-positive lymphoblastoid cell lines. Cells of these established lines are susceptible to renewed infection by P3HR-1 EBV which results in EA induction and VCA synthesis. Only cells of one line, NC37-R1, spontaneously produce VCA and EBV particles, which reveal transforming properties and do not induce EA upon superinfection of Raji cells. Infection of P3HR-1 EBV-converted BJA-B cells also leads to EA and VCA induction and the release of viral particles. In contrast to particles recovered from Raji and NC37 cells, no transforming activity was detectable in these virus preparations. According to these data, we propose that viral genomes persisting within Raji and NC37 cells are defective and become complemented by the superinfecting P3HR-1 virus.

Antigens, Viral↗
PubMed1978

Heterogeneity of Epstein-Barr virus. IV. Induction of a specific antigen by EBV from two transformed marmoset cell lines in Ramos cells.

Infection of cells of the EBV-genome-negative human B-lymphoma Ramos line with viral isolates obtained from two EBV-transformed marmoset cell lines (B95/8; Nyevu) resulted in the induction of a nuclear antigen (RAM-ag) apparently different from other EBV-associated antigen complexes. This antigen is revealed by indirect immunofluorescence and shows no detectable cross-antigenicity with EBNA or any other known EBV-associated antigen. EBV-isolates from P3HR-1 cells fail to induce a similar antigen in Ramos cells although they induce EBNA. No RAM-ag was expressed, either after infection of cells of another EBV-genome-negative human B-lymphoma line BJAB with B95-8 EBV or in a series of EBV-harbouring cell lines. Thus the antigen appears to be cell-line-specific for Ramos cells. It is also induced upon infection of either B95-8 or P3HR-1 converted Ramos sublines with EBV from B95-8 cells. All human sera with RAM-ag-reactivity revealed antibodies against VCA. However, sera from patients with acute infectious mononucleosis containing high anti-VCA-antibodies did not react with RAM-ag. Seroconversion for this antigen apparently more closely coincides with the appearance of EBNA-directed antibodies.

Animals↗
PubMed1978

Heterogeneity of Epstein-Barr virus derived from P3HR-1 cells.

Infection of cells of the EBV-free human B-lymphoma lines BJAB and Ramos resulted in conversion of these cells to EBV-genome carriers expressing EBNA. EBV isolates from P3HR-1 cells induced a heterogeneous EBNA pattern: both a faintly granular pattern and brilliant EBNA-expression were observed. The two types of EBNA-expressing cells could be separated upon cloning. Brilliantly EBNA-expressing cells always segregated varying percentages of EBNA-negative cells. An EBNA-negative subclone derived from these cells was devoid of detectable EBV DNA. Nucleic acid hybridization experiments failed to reveal a correlation between the intensity of EBNA expression and the number of EBV genome equivalents per cell. EBV genome-containing cells had an average of 14-fold more cells showing EA synthesis after superinfection by P3HR-1 virus, when compared with EBNA-negative cells infected under identical conditions. Studies on the kinetics of EA induction in EBNA-positive and EBNA-negative cells indicate that complementation is required for the induction of EA after superinfection.

Antigens, Heterophile↗
PubMed1977

[Isoenzyme pattern of acid phosphatase in epstein-barr-virus-DNA positive permanent growing lymphoid cell lines (author's transl)].

The expression of acid phosphatases is cytochemically one of the most important features in permanent growing B-cell-lines. In few cell lines acid phosphatase is resistant against tartrate. Tartrate resistant isoenzyme 5 with components a and b can be demonstrated in monocytes, lymphocytes, chronic lymphatic leucemic cells and especially in hairy cells as well as in cell lines derived from a healthy donor. Fractionation of acid phosphatase by gelelectrophoresis in separated lymphocytes demonstrates especially isoenzyme 3, in separated macrophages isoenzyme 4. Isoenzyme 4 could not be detected in several cell lines. It is therefore concluded that these cell lines are probably derived from lymphocytic precursors. Cell lines with isoenzyme 4 may be the result of a facultative hybridisation between lymphocytes and monocytes. Profiles of acid phosphatases in virus-negative cell lines (Ramos, BJAB) were not significantly altered by conversion with EBV.

Acid Phosphatase↗
PubMed1977

Heterogeneity of Epstein-Barr virus originating from P3HR-1 cells. I. Studies on EBNA induction.

Infection of EBV-negative human B-lymphoma cells of the lines BJAB and Ramos with EBV from P3HR-1 or B95-8 cells resulted in gradual conversion of these cells to EBNA synthesis. Whereas B 95-8 virus-infected cells exhibited a uniform brilliant EBNA fluorescence, two distinct fluorescence patterns were observed in P3HR-1 virus-converted BJAB and Ramos cells, a faint granular and a brilliant fluorescence, with predominance of the faint granular pattern. Cloning of P3HR-1 virus-converted BJAB cells resulted in 20 clones, 11 of them showing the heterogenous parental pattern, six revealing exclusively faint granular EBNA staining, and three with brilliantly stained nuclei, containing also a varying percentage of EBNA-negative cells. Further subcloning of one of the latter clones resulted in 26 subclones with brilliant EBNA expression, always segregating a significant percentage of EBNA-negative cells and one entirely EBNA-negative subclone. Reassociation kinetics did not reveal striking differences in the genome content of clones showing exclusively the faint granular or the brilliant type of EBNA expression. The EBNA-negative clone did not contain detectable amounts of EBV-DNA. Upon superinfection of the converted clones by the parental P3HR-1 virus, a significant increase in EA induction was noted when compared to non-converted BJAB and Ramos cells. This accounted in particular for cells with faint granular EBNA expression. These data support previous interpretations (Fresen and zur Hausen, 1976), suggesting the existence of at least two populations of EBV molecules within P3HR-1 cells. The reason for the apparently labile association of P3HR-1 EBV genomes inducing the brilliant EBNA flourescence in BJAB cells still remains obscure. The possible existence of a "helper" effect, exerted by the faint granular EBNA-inducing virus in stabilizing the persistence of the former, is discussed.

Cell Line↗
PubMed1977

Transient induction of a nuclear antigen unrelated to Epstein-Barr nuclear antigen in cells of two human B-lymphoma lines converted by Epstein-Barr virus.

Infection of cells of the Epstein-Barr virus (EBV)-negative human B-lymphoma lines BJAB and Ramos with EBV preparations from P3HR-1 or B 95-8 cells converted these cells to EBV genome carriers expressing Epstein-Barr nuclear antigen (EBNA) in almost 100% of these cells. Induction of these cells as well as of clones from P3HR-1 EBV-converted BJAB cells with iododeoxyuridine, aminopterin, and hypoxanthine resulted in the appearance of a nuclear antigen in about 1-6% of the cells 1-4 days after induction. The antigen is different from known EBV-induced antigens like EBNA, viral capsid antigen (VCA) or the D- and R-subspecificities of the early antigen (EA) complex. It is demonstrated by indirect immunofluorescence and inactivated after acetone fixation. The antigen was not detectable after induction of uninfected BJAB and Ramos cells nor has it been found in noninduced or induced P3HR-1 and Raji cells. Thus, it appears that EBV-infection mediates the expression of this antigen, for which the name TINA (transiently induced nuclear antigen) is suggested. Sera reacting against TINA generally contained high antibody titers against EBV-induced EA. Only a limited number of highly EA-reactive sera, however, were also positive for TINA. Among 200 sera tested thus far, TINA reactivity was most frequently observed in sera of patients with nasopharyngeal carcinoma (7 out of 28), in sera of the only two patients with immunoblastoma tested and occasionally in sera from patients with Hodgkin's disease and chronic lymphatic leukemia. Among 70 sera from nontumor patients, TINA reactivity was observed three times: two patients suffered from "chronic" infectious mononucleosis, the other revealed persistent splenomegaly.

Aminopterin↗
PubMed1976

Establishment of EBNA-expressing cell lines by infection of Epstein-Barr virus (EBV)-genome-negative human lymphoma cells with different EBV strains.

Cells of two EBNA (Epstein-Barr virus nuclear antigen)-negative human lymphoma cell lines, BJAB and RAMOS, were infected with two strains of Epstein-Barr virus (EBV). In two different experiments, B95-8 virus-infected BJAB cells revealed a gradually increasing number of EBNA-positive cells. Twenty weeks after infection almost 100% of the cell population expressed this antigen. In contrast, it has not so far been possible to convert RAMOS cells into an EBNA-positive cell line. The initial proportion of 35% EBNA-positive cells declined to about 10% 20 weeks after infection. The development of EBNA-positive multinuclear giant cells was a characteristic feature of infection with B95-8 virus. EA (early antigen) and VCA (virus capsid antigen) appeared in less than 0.1% of the cell population after induction with IUdR only. Infection of BJAB and RAMOS cells with P3HR-1 virus finally resulted in both cases in EBNA-positive lines. In contrast to B95-8 virus, the number of EBNA-positive lines. In contrast to B95-8 virus, the number of EBNA-positive cells remained below 1% during the first 6 to 8 weeks. A sudden increase occurred thereafter, bringing the number of EBNA-expressing cells to almost 100% within the following 4 weeks. During this period, BJAB but not RAMOS cells revealed a small number of EA- as well as VCA-positive cells (less than 0.1%). Thus, reinfection by spontaneously released virus may explain the sudden increase in EBNA-positive BJAB cells. Two distinct patterns of EBNA staining in P3HR-1 virus-infected cells were observed. They may suggest a genetic heterogeneity of this virus preparation.

Antigens, Viral↗