3種類の疾患から得られたEpstein-Barr virus (EBV) の生物学的特性に関する実験的追求

抄録

Growth characteristics and Epstein-Barr virus (EBV) induction in EBV-genome-negative Ramos Lymphoma lines and three sublines of Ramos (Ramos/B 95-8, AW-Ramos and Ramos/NPC) carrying different EBV-genomes derived from cells of infectious mononucleosis (IM), Burkitt's lymphoma and nasopharyngeal carcinoma (NPC) were comparatively examined. In addition, the difference of growth characteristics and immunoglobulin production in human cord blood lymphoblastiod cell lines (CBLs) transformed by two strains of EBV (B 95-8 and NPC-KT) derived from cells of IM and NPC were also studied. Cells of EBV-genome-negative Ramos line died rapidly after having reached saturation density, whereas all three cells of EBV-genome-positive Ramos sublines maintained constant number of living cells for several weeks even after having reached saturation density. However, no differences were shown in growth chracteristics between cells of Ramos sublines and CBLs which carry different EBV genomes.
On the other hand, there was a clear difference in EBV induction after the treatment of cells of EBV-genome-positive Ramos sublines with 12-tetradecanoylphorbol-13-acetate, n-butyric acid, and 5-iododeoxyuridine. Ramos/B 95-8 and AW/Ramos cells could synthesize early antigen (EA) after their treatment with the above chemical drugs, whereas Ramos/NPC cells could not show EA induction after the treatment of cells with any chemical drugs. From three different blood samples (human cord, human adult seronegative, and cotton-top marmoset bloods), total six cell lines were established by exposure to either B 95-8 strain or NPC-KT strain. All these established cell lines contained more than 90% EBV-associated nuclear antigen (EBNA)-positive cells. While tranforming virus could regularly be rescued from human adult and cotton-top marmoset lymphocytes tranformed by either B 95-8 or NPC-KT virus strain, attempts to rescue virus from human cord blood lymphocytes transformed by two virus strains or from the EBV-converted Ramos sublines (Ramos/B 95-8 and Ramos/NPC) were unsuccessful. In addition, only virus stock obtained from cotton-top marmoset lymphocytes transformed by NPC-KT EBV strain could superinfect Raji cells.
From these results, it was suggested that characteristics of the EBV-transformed lymphoblastoid cell lines and their EBV production may be determined by cellular facters and mutual interaction between cells and EBV strains employed rather than the differences among the virus strains.