Differential gene expression patterns of EBV infected EBNA-3 positive and negative human B lymphocytes

The genome of Epstein-Barr virus (EBV) encodes 86 proteins but only a limited set is expressed in EBV-growth transformed B cells, termed lymphoblastoid cell lines (LCLs). These cells proliferate via the concerted action of EBV nuclear antigens (EBNAs) and latent membrane proteins (LMPs), some of which are rate limiting to establish a stable homeostasis of growth promoting and anti-apoptotic activities. We show here that EBV mutants, which lack the EBNA-3A gene, are impaired but can still initiate cell-cycle entry and proliferation of primary human B cells in contrast to an EBNA-2-deficient mutant virus. Surprisingly and in contrast to previous reports, these viral mutants are attenuated in growth transformation assays but give rise to permanently growing EBNA-3A negative B cell lines which exhibit reduced proliferation rates and elevated levels of apoptosis. Expression profiles of EBNA-3A deficient LCLs are characterized by 129 upregulated and 167 downregulated genes, which are significantly enriched for genes involved in apoptotic processes or cell cycle progression like the tumor suppressor gene p16/INK4A or might contribute to essential steps in the viral life cycle. In addition EBNA-3A cellular target genes remarkably overlap with previously identified targets of EBNA-2.

14

Hertle ML, Popp C, Petermann S, Maier S, Kremmer E, Lang R, Mages J, Kempkes B