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M Nonoyama

Publications and source records attributed to M Nonoyama.

At least 145 records · Page 8Linked to original sources
PubMed1978

Transcription of Epstein-Barr virus genomes in human lymphoblastoid cells and in somatic-cell hybrids of Burkitt's lymphoma.

Expression of latent Epstein-Barr virus genomes in lymphoblastoid cells and somatic-cell hybrid of Burkitt's lymphoblastoid cells has been studied. IUDR treatment induced the formation of early antigen (EA), virus capsid antigen (VCA) and virus DNA replication in D98/Raji and D98/HR-1 cells whereas only EA was induced in Raji cells. HR-1 clone No. 9 did not respond to IUDR treatment. The pattern of transcription of virus genomes in these cell lines without IUDR treatment was uniform with 20--25% of virus DNA transcribed. IUDR treatment enhanced the transcription of virus DNA to 50% in D98/Raji, D98/HR-1 and Raji cells but no enhancement of virus genome transcription was observed in HR-1 clone No. 9 The amount of virus RNA in the cells calculated from DNA-RNA hybridization kinetics was found to be proportional to the number of virus genomes per cell indicating that every copy of virus DNA in these cells is actively transcribed.

Burkitt Lymphoma↗
PubMed1978

Studies on the association of the Epstein-Barr virus genome with chromosomes in human (Burkitt)/mouse hybrid cells.

We have used somatic-cell hybrids of mouse fibroblast and Burkitt's lymphoblastoid tumour cells to continue our investigation of the association between Epstein-Barr virus (EBV) genome and human chromosomes. A mouse/Burkitt hybrid cell, designated CL1D/HR-1, was cloned in soft agar. Each of 10 clones was assayed for the spontaneous expression of EBV-associated nuclear antigen (EBNA), early antigen (EA) and virus capsid antigen (VCA). Six of 10 clones were EBNA-positive but negative for EA and VCA even after treatment with iododeoxyuridine. One clone, designated M44, contained approximately 90% EBNA-positive cells and 0.3--0.5 EBV genome equivalents per cell. Thirty subclones of clone M44 were obtained and analysed for EBV DNA, EBNA and human chromosomes. Four subclones (three EBNA-positive and one EBNA-negative) were studied in detail. Data obtained thus far indicate that none of the four subclones of clone M44 studied contained any intact human chromosome. Isozyme analysis of these subclones indicated that all four subclones, regardless of the status of the EBV genome, synthesized nucleoside phosphorylase, an enzyme which has been linked to human chromosome number 14.

Animals↗
PubMed1977

Enhanced oncogenic behavior of human and mouse cells after cellular hybridization with Burkitt tumor cells.

Studies were made of the expression of the Epstein-Barr virus (EBV) in somatic hybrids of Burkitt tumor cells and human or mouse cells to determine whether EBV genetic information associated with the capacity to transform leukocytes of human and non-human primates could be maintained and expressed in nonlymphoblastoid cells. Data obtained thus far suggest that at least one characteristic associated with cellular transformation (loss of contact inhibition) is expressed only in nonlymphoblastoid cells in which the EBV genome is maintained. In addition, we have demonstrated that human epithelial/Burkitt hybrid cells (D98/HR-1 and D98/Raji) are more oncogenic in nude (athymic) mice than are cells of the human epithelial parental line, D98, or one of the Burkitt lymphoblastoid parent cell lines (Raji); the HR-1 Burkitt parent cell line was as oncogenic as the hybrid cell lines but the time required to induce tumors was much longer. Thus, human epithelial cells show alteration of growth properties in vitro and in vivo after cellular hybridization with Burkitt tumor cells.

Animals↗
PubMed1976

Properties of a baboon lymphotropic herpesvirus related to Epstein-Barr virus.

Three lymphoblastoid cell lines were established from splenic lymphocytes of a lymphomatous baboon (Papio hamadryas) by co-cultivation of the lymphocytes with X-irradiated cells of marmoset or baboon lymphoblastoid cell cultures; the baboon splenic lymphocytes failed to grow when cultured alone. A herpesvirus, associated with each cell line, was identified by immunofluorescence, molecular hybridization and electron microscopy. Antigenic comparison with Epstein-Barr virus (EBV) showed that the baboon herpesvirus and EBV shared cross-reacting viral capsid antigens (VCA): 20 of 20 (100%) anti-VCA (EBV)-positive human sera and 55 of 62 (89%) baboon sera reacted with the baboon lymphoblastoid cells and baboon sera stained EBV VCA in P3HR-1 and EB-3 cells. No nuclear antigen, as assayed by anti-complement immunofluorescence tests, was detected in baboon lymphoblastoid cells when human or baboon anti-VCA positive sera were used. Baboon anti-VCA-positive sera also failed to stain EBV nuclear antigens (EBNA) in Raji or P3HR-1 cells. Preliminary molecular hybridization studies showed only approximately 40% homology between viral DNA of baboon cell lines and DNA of EBV derived from P3HR-1 cells.

Animals↗
PubMed1976

Mechanisms of infection with Epstein-Barr virus. I. Viral DNA replication and formation of noninfectious virus particles in superinfected Raji cells.

Human lymphoblastoid Raji cells, which do not produce virus, supported replication of Epstein-Barr virus (EBV) upon superinfection. Early antigen, viral capsid antigen, and virions were produced in Raji cells superinfected with EBV. Viral DNA replicated under complete inhibition of host cell DNA synthesis to the extent that a few micrograms of EBV DNA were recovered from 107 superinfected Raji cells, corresponding to 5,000 viral genomes/cell. Homology of the synthesized viral DNA to parental EBV DNA was more than 90%. Virions produced by the Raji cells contained a 55S DNA but failed to induce early antigen, viral capsid antigen, and viral DNA synthesis after a second superinfection of Raji cells.

Antigens, Viral↗
PubMed1975

Plasmid DNA as a possible state of Epstein-Barr virus genomes in nonproductive cells.

It has been shown that the EBV DNA in Raji cells is located in chromosomes and that most of this EBV DNA can be separated from high molecular weight cell DNA both in alkaline and neutral glycerol gradients. The data indicate that the latent EBV DNA may exist possibly as a plasmid DNA. As 50 genomes of EBV DNA are equal to 0.1% of the total cell DNA, it may be quite conceivable that such an amount of DNA should remain in a non-integrated form. Chromosomal location may be a requisite for any DNA to persist in the nucleus of cells and to be divided into daughter cells evenly. As the present studies measured only the status of the major portion of EBV genomes in Raji cells, a possibility still remains that a few genomes of EBV may be linearly integrated into cell DNA and these may be responsible for cellular transformation. Another possibility that a small piece of cellular DNA might be attached to EBV DNA in Raji cells, which might serve as a control signal for replication and/or transcription of the latent virust DNA, has also not been ruled out. Even though EBV DNA is not integrated covalently into cell DNA, the association of the virus genomes with cells is very stable and the number of EBV genomes remains unchanged throughout many cell generations. In synchronized cells, all EBV genomes replicate simultaneously at an early S phase before maximum synthesis of cell DNA replication occurs (Hamper et al. 1974). This indicates that EBV DNA in a plasmid state is strictly under a cellular control mechanism. How this latent virus DNA is controlled in cells will be examined in future studies.

Cell Line↗
PubMed1975

Detection of Epstein-Barr virus DNA in human tumors.

The presence of Epstein-Barr virus (EBV) DNA in biopsies of human tumors was tested by complementary RNA (cRNA) hybridization on membranes and DNA-DNA reassociation kinetics. DNA-DNA reassociation kinetics can detect as few as 1 EBV genome in every 50 cells, and the cRNA method can detect EBV genomes if 2 or more are present in a cell. Twenty-three out of 24 African Burkitt's lymphoma biopsies, 18 out of 23 African nasopharyngeal carcinomas (NPC), and 8 out of 24 other African tumors were positive for EBV DNA. Three cases of American Burkitt's lymphoma were tested by the cRNA method, and EBV DNA was not detected. Three out of 25 American tumors other than American Burkitt's lymphoma contained 0.1 to 0.3 genomes per cell of EBV DNA.

Africa↗