Complementation between infecting Epstein-Barr virus and intrinsic viral genomes in human lymphoid cell lines

13 human lymphoid cell lines previously characterized in terms of their intrinsic Epstein-Barr virus (EBV) genome content were infected or superinfected with EBV from the supernatant of P3HR-1 cells. The cell lines included 2 lymphoma cell lines that contain no detectable EBV genomes and 11 cell lines containing intrinsic EBV genomes. All the cell lines responded to EBV infection by expressing early antigen (EA). The number of EA-positive cells in the cultures was proportional to the viral concentration used for infection or superinfection. However, cell lines containing multiple intrinsic EBV genomes expressed higher amounts of EA-positive cells. Evaluation of EA expression versus the number of intrinsic EBV genome copies per cell in each line revealed EA to increase as the intrinsic EBV genome content of the cell lines increased in a nonlinear curve that was described by an exponential logistic function. The coefficient of determination R2 for this curve was greater than 0.9 for multiple experiments. The data suggest that 80-90% of the virus in P3HR-1 is defective and requires intrinsic viral genomes for expression of EA. Transactivation or complementation between intrinsic EBV genomes and infecting virus is supported by these observations.