Circular Epstein-Barr virus genomes of reduced size in a human lymphoid cell line of infectious mononucleosis origin.

Circular Epstein-Barr virus (EBV) DNA molecules have been purified and characterized from a human lymphoid cell line derived from a case of heterophile antibody-positive, blood transfusion-induced infectious mononucleosis, 883L. The circular EBV DNA in three cell lines obtained by transformation of human umbilical cord blood leukocytes with a strain of EBV originally derived from 883L was also studied. As estimated from sedimentation velocity data and electron microscopy, the circular EBV DNA molecules are 10 to 15% smaller than either the circular EBV DNA previously found intracellularly in several other types of EBV-transformed cells or the linear EBV DNA present extracellularly in virus particles. In addition, the EBV-transformed cord blood cell lines studied here differed from other EBV-transformed cells in that integrated virus DNA sequences could not be detected.