[Potential role of Epstein-Barr virus in Sjögren's syndrome]

In this review, I discuss recent progress in our understanding of the role of Epstein-Barr virus on pathological conditions in Sjögren's syndrome (SS). In order to clarify the association of EBV in SS pathogenesis and further analyze the precise transcriptional mechanism of EBV reactivation, we assayed transcription of ZEBRA which is the fast transcribed EBV-encoded immediate early gene product and was an indispensable role in EBV reactivation. The ZEBRA expression was observed in the ductal epithelial cells and infiltrating B cells, and SS peripheral blood lymphocytes (PBL). On the other hand, to identify the inducer of EBV reactivation, we have used in vitro EBV reactivation model cell line. Screening of cDNA by mRNA differential display subtraction method, one clone, named "AK-1", was highly expressed in SS PBL. Nucleotide sequence analysis revealed that AK-1 was complete match with p300/CBP-associated factor (P/CAF). Furthermore, as another approach, we have partially cloned cDNA with a novel sequence containing a region homologous to the basic leucin zipper domain of CREB/ATF family by degenerate PCR. Our results together with recent reports, suggest the possibility that CREB family protein-p300-P/CAF ternary complex on ZEBRA promoter might be involved in ZEBRA transcriptional activation.