Size heterogeneity of EBV and mitochondrial DNAs in Burkitt's lymphoma lines

Abstract

A simple, reproducible affinity chromatography method has been adapted for separation of high molecular weight supercoiled circular molecules from mammalian cells. Electron microscopic analysis of EB viral DNA obtained by this method, from the non-producer Burkitt's lymphoma line Raji, revealed monomer-sized viral molecules only. In contrast, the EB viral episomes from recently established human producer lines BL-8 and LY91 were very heterogeneous in size, some being considerably smaller and others much larger than the monomeric DNA. The former are probably related to defective viral species in the B-cell population, but the origin of the latter are as yet unclear. All cell lines contained both monomers and concatemers of mitochondrial DNA; among the latter, molecules apparently greater than 100 kb were observed in the population.

Marked variation in the size of genomic plasmids among members of a family of related Epstein-Barr viruses.

“…Although EBV DNA plasmids of non-standard length have been seen by electron microscopy in some Burkitt lymphoma cell lines, the molecules were not positively identified as EBV (31,32). The pulsed Gardella gel technique may also be useful in the study of other large circular DNA molecules-for example, latent herpes simplex virus (33) Snificance of the Findings.…”

Complexities associated with expression of Epstein-Barr virus (EBV) lytic origins of DNA replication

“…Recombination events at the TRs lead to generation of a circular, supercoiled plasmid species, the prevalent form of EBV found in infected cells. Repeat copy numbers dictate the genome size (from 170 to >200 kb) in different strains of the virus (7). …”

Expression of Two Related Viral Early Genes in Epstein-Barr Virus-Associated Tumors

“…1). In some BL-derived lines that have not been continuously passaged in culture, the viral DNA does not appear to be uniform in size (22), whereas in established and frequently passaged lines, a single-sized molecule appears to predominate (28). The same may be true for NPC (36).…”

“…In more recent years, an EBV association has been identified with other hematological malignancies, including Hodgkin's disease and T-cell lymphoma, as well as with numerous lymphoepitheliomas, including gastric carcinoma (as reviewed in reference 1), and also with some cases of breast cancer (4,24). The viral genome is a double-stranded DNA molecule ranging from 172 kbp in B95-8 cells (3) to even larger sizes in other B-cell lines (22). It contains several major internal repeats, designated IR1 to IR4, interspersed throughout the genome and a terminal repeat located at the ends of virion DNA or internally in episomal forms of the genome.…”