Detection of Epstein-Barr Virus DNA in Nasopharyngeal Biopsies
Epstein-Barr Virus (EBV) is closely associated with undifferentiated nasopharyngeal carcinoma (NPC) and Burkitt’s lymphoma (BL) where the virus genome is stably maintained and only partially expressed, e.g., the nuclear antigen (EBNA). The possibility of integration of EBV DNA into cellular DNA in latently infected nasopharyngeal epithelial cells over years of active cell replication is supported by the finding that viral DNA is localized on both chromatids of one homologue of chromosome 1 in Namalwa (a BL cell line) and on both chromatids of one homologue of chromosome 4 in IB4 (a cell line with transformed growth properties) (1). The results of restriction mapping of Raji cellular DNA obtained after separation on CsCl gradients suggest that viral DNA is integrated into cellular DNA at the region of 52032 end of the BamHl W fragment (2). It is not understood how EBV is maintained in NPC tumor cells.