Epstein-Barr Virus Stimulates Torque Teno Virus Replication: A Possible Relationship to Multiple Sclerosis

Borkosky, Silvia S.; Whitley, Corinna; Kopp-Schneider, Annette; zur Hausen, Harald; deVilliers, Ethel-Michele

Seven hematopoietic cell lines, either EBV-positive or EBVnegative, were selected for this study. Burkitt's lymphoma cell lines included BJAB and Ramos, both EBV-negative [98, 99] and P3HR-1 harboring an EBV genome in which the EBV nuclear antigen-2 (EBNA-2) has been deleted [76] . For comparison we included the BJAB and Ramos cell lines which had previously been converted to EBV-positive by infection with the EBV genome originating from the P3HR-1 cell line, BJAB/EBV and Ramos/EBV [98, 100] . In addition, two B cell lines were included. A human EBV-immortalized B cell line ND1, established from an MS patient (kind gift from M. Sospedra) and the EBV-producing B95-8 cotton-top marmoset cell line [77] . EBV DNA was quantified using serial dilutions of Namalwa DNA (human Burkitt's lymphoma cell line containing 2 EBV genome copies per cell, kindly provided by Regina Feederle) as reference for a standard curve [75] . All cell lines (mycoplasma free as confirmed by PCR) were maintained in RPMI 1640 medium supplemented with 10% fetal calf serum and 1% penicillin-streptomycin in 5% CO 2 at 37uC.