G: Latent and replicating forms of Epstein-Barr virus DNA in lymphomas and lymphoproliferative diseases

Epstein-Barr virus (EBV) is associated with lymphomas and lymphoproliferative diseases that occur mainly in immunocompromised patients, but the role EBV plays in their patho-genesis is unclear. The evidence linking EBV etiologically to these disorders includes the presence of EBV DNA and nuclear antigens in the lesions and serologic evidence that some patients with these lesions are experiencing primary or reactivated EBV infections. These syndromes may represent proliferation of cells latently infected with EBV, but the possibility of viral replication has not been rigorously studied. DNA extracted from biop-sies of 35 lymphoproliferative diseases was probed with regions of the EBV genome capa-ble of distinguishing circular, episomal DNA found in latency from linear, replicating EBV DNA. All samples contained restriction fragments characteristic of fused termini, indicative of circular, latent genomes. Thirteen samples contained additional restriction fragments diagnostic of linear EBV DNA. Therefore, replicating EBV DNA is found in (\)400/0 of EBV-associated lymphoproliferative disorders. Epstein-Barr virus (EBV) can manifest two differ-ent life cycles: latent and replicative. In lymphoid cell