Amplification of Epstein-Barr virus (EBV) DNA by superinfection with a strain of EBV derived from nasopharyngeal carcinoma

Abstract

Epstein-Barr virus (EBV) from a nasopharyngeal carcinoma (NPC) hybrid cell line (NPC-KT) lacking defective viral DNA molecules superinfected Raji cells and induced EBV early antigens (EA), as did virus from P3HR-1 cells, which contained defective molecules. The EBV polypeptides induced by NPC-KT appeared to be identical to those induced by P3HR-1 virus. The ability of NPC-KT virus to induce EA was enhanced more than 10-fold by treatment of superinfected cells with dimethyl sulfoxide; however, dimethyl sulfoxide treatment did not enhance superinfection by P3HR-1 virus. After infection, DNA synthesis of both the superinfecting NPC-KT virus and the resident Raji viral genome was induced. In addition to amplified Raji EBV episomal DNA, a fused terminal fragment of NPC-KT viral DNA was detected. The detection of fused terminal DNA fragments suggests that the superinfecting virion DNA either circularizes or polymerizes after superinfection and is possibly amplified through circular or concatenated replicative intermediates.

Molecular markers of clonality and identity in epstein–barr virus‐associated B‐cell lymphoproliferative disease

“…There are three possible explanations for these results: (1) the 2a-F1 EBV genotype may have infected and transformed a precursor B-lymphocyte, prior to immunoglobulin gene rearrangement, that subsequently gave rise to subclonal populations with different immunoglobulin gene structures [Katamine et al, 1984]. In this case, the dual-EBV-infected tumors would represent multi-focal monoclonal expansion of one of these subclonal cells after subsequent superinfection by the 2a-G EBV genotype [Sato et al, 1988]. (2) The dual-EBV-infected monoclonal tumor may be present in the spleen in low Fig.…”

Concatameric replication of Epstein-Barr virus: structure of the termini in virus-producer and newly transformed cell lines

“…As described above, the RI template for NPC-KT virus DNA apparently contains a single joined terminal fragment of 9.4 kb representing four copies of TR (25). Upon entry into cells, NPC-KT virus circularized to form fused termini ranging in size from 8.4 to 10.4 kb, representing two to six copies of TR.…”

Cytopathic effects induced by Epstein-Barr virus replication in epithelial nasopharyngeal carcinoma hybrid cells

“…In order to examine the terminal structure of EBV DNA synthesized in IUdR-induced cl.S61 cells, Southern blot analysis was performed with the XhoI 1.9-kilobase (kb) probe, which represented unique DNA adjacent to the repeat sequence at the right terminus (12). The right-terminal BamHI fragment of EBV DNA contained approximately 3.5 kb of unique DNA and various numbers of 0.5-kb terminal repeats.…”