Characterization of Epstein‐Barr viral strains in parotid gland saliva and peripheral blood of patients with primary Sjögren's syndrome and healthy EBV carriers

Abstract Increased Epstein‐Barr virus (EBV) replication has been reported in the salivary and lacrimal glands in Sjögren's syndrome (SS). We studied whether or not certain EBV strains would occur preferentially in the peripheral blood and parotid gland saliva of 18 EBV‐seropositive patients with primary Sjögren's syndrome (pSS) and 12 EBV‐seropositive control persons. Transforming EBV was detected in the blood of 11 of 18 (61%) pSS patients and 9 of 12 controls (75%). Unexpectedly, neither transforming nor Raji‐superinfecting EBV strains were detected in SS parotid saliva, whereas these EBV types were detected in control saliva in 7 and 8 cases, respectively (P <0.001). Transforming EBV strains were further characterized by ‘Ebnotyping,’ i.e., analysis of the size spectrum of the viral antigens EBNA 1, 2, 3, and 6 in immunoblots of lymphoblastoid cell lines (LCL). Previous work has shown that a single EBV strain (Ebnotype) dominates the blood and oropharynx of healthy carriers and that unrelated individuals carry different EBV strains, reflecting the vast polymorphism of Ebnotypes in the general population. Two unexpected observations were made. First, an identical Ebnotype was detected in 4 unrelated individuals, i.e., in the blood of 1 pSS patient and in the saliva of 3 control persons. Second, carriage of 2 to 4 different Ebnotypes by a single individual was observed in 4 cases, i.e., in the blood of 1 pSS patient, and in the blood and saliva of 3 control persons. As only 1 control person had received a blood transfusion, it is suggested that (super)infection with exogenous EBV strains via salivary transmission and/or recombination of endogenous virions may have contributed to this situation.