Improved production of Epstein-Barr virus DNA for nucleic acid hybridization studies

Sedimentation characteristics of newly synthesized Epstein-Barr viral DNA in superinfected cells

Replicating Epstein-Barr virus (EBV) DNA molecules isolated from superinfected Raji cells were shown to consist of 80S to 65S and 58S (mature) molecules Pulse-chase experiments showed that radioactive label of DNAS molecules with the larger sedimentation coefficients was partially chased into 58S labeled forms. Formation of large concatemers of viral DNA could not be detected at any time after superinfection. The continuous presence of the 65S viral DNA intermediate throughout the replicative cycle combined with the observed inhibition of EBV DNA synthesis by addition of nontoxic levels of ethidium bromide to the superinfected cell culture led us to propose that EBV replication proceeds via a relaxed circular DNA intermediate.

Transcription and circular dichroism of chromatin in lymphoblastoid cell lines during proliferation and quiescence

RNA polymerase activity of nuclei and positive circular dichroism ellipticity in the 250--300 nm region of chromatin were studied in three lymphoblastoid cell lines: HRI, an Epstein-Barr Virus (EBV) positive virus-producing line; Raji, and EBV positive virus-producing line; Raji, an EBV positive non-producer line; and SU-AMB-1, and EBV negative line. Raji consistently exhibited the highest and SU-AMB-1 the lowest polymerase activity and ellipticity. All lines showed higher RNA polymerase activity and positive ellipticity when exponentially growing than when stationary. In Raji it was shown that changes in RNA polymerase activity and chromatin ellipiticity were parallel. The changes in RNA polymerase activity of nuclei and circular dichroism ellipticity correlated with those of the proliferative state but not with the number of viral genomes or the production of virus or viral antigens.

Studies on the association of the Epstein-Barr virus genome and human chromosomes

We have used human-mouse somatic cell hybrid to study the association between the EBV genome and the cellular genome. Attempts were made to identify a specific human chromosome(s) with which the EBV genome is associated. Our data suggest that at least in the mouse fibroblast/Burkitt lymphoma hybrid combination studies, the EBV genome is not associated with any specific human chromosome.

Further characterization of a herpesvirus-positive orang-utan cell line and comparative aspects of in vitro transformation with lymphotropic old world primate herpesviruses

An orang-utan (Pongo pygmaeus) suspension line, CP81, was shown to lack myeloid markers of lysozyme activity an d phagocytosis but to be positive for lymphocytic N-alkaline phosphatase activity, and to release a B-cell-tropic herpesvirus. This herpesvirus, termed Herpesvirus pongo, had 30--40% DNA homology with EBV and was present at 2-3 genome copies per CP-81 cell. Gibbon lymphocytes transformed by H. pongo, Epstein-Barr virus (EBV), and H. papio (of baboon, Papio hamadryas, origin) were found to be virus antigen-positive B cells. Gibbon lymphocytes transformed by H. pongo and EBV and transplanted to nude mice by the intracranial (IC) route (had a 75% and a 45% success rate, respectively), while transplants of similar cells transformed by H. papio were only 10% successful. None of these lines transplanted subcutaneously (SC) nor manifested a high degree of colony formation in 0.33% agarose (less than or equal to 0.5%), Gibbon lymphocytes transformed by H. pongo were hypodiploid while those transformed by EBV or H. papio were diploid. CP-81 cells themselves could be transplanted both IC (100%) and SC (70%) and showed a relatively high degree of colony formation in agarose (6.4-7.6%). B95-8 cells (marmoset, Saguinus oedipus-EBV) could be transplanted IC (66%) but not SC and had a low but significant ability to grow in agarose (1.6%). 594S (baboon, P. hamadryas-H. papio) cells could be transplanted IC (25%) but not SC, and grew to very low levels in agarose (0.1%).