Sites of Epstein-Barr virus replication in acute and chronic active Epstein-Barr virus infections

We examined Epstein-Barr virus (EBV) in saliva samples and peripheral blood mononuclear cells (PBMC) from 9 patients with acute infectious mononucleosis (IM) and 4 patients with chronic active EBV infection (CEBV). All saliva samples from patients with acute IM were positive for EBV by both Southern blot hybridization assay and the cord transformation assay. In contrast, EBV DNA could not be detected in saliva samples from patients with CEBV. Only one of the saliva samples from 4 patients with CEBV could transform cord blood lymphocytes with extreme difficulty. No saliva samples from patients with CEBV were capable of inducing early antigens in Raji cells. On the other hand, EBV DNA was detected in PBMC from 3 of the 4 patients with CEBV but not in those from patients with acute IM by Southern blot hybridization. Spontaneous lymphoblastoid cell lines could be easily established from PBMC of patients with acute IM but not from PBMC of patients with CEBV, despite several attempts. Viral capsid antigen and early antigens were not observed in cultured cells from patients with CEBV. These results suggest that the main site of EBV replication in CEBV might not be oropharyngeal epithelial cells.