EPSTEIN-BARR-VIRUS LATENT MEMBRANE PROTEIN-2A BLOCKS CALCIUM MOBILIZATION IN B-LYMPHOCYTES

LMP2A is expressed in latent Epstein-Barr virus (EBV) infection and interacts with LMP1 and members of the src tyrosine kinase family in the plasma membrane. Since tyrosine kinases mediate receptor-induced changes in intracellular free calcium, the effect of LMP2A on receptor-mediated intracellular calcium mobilization was evaluated by stably expressing LMP2A in an EBV-negative Burkitt tumor cell line (BJAB) or in LMP1-converted BJAB cells. LMP2A significantly blocked calcium mobilization following class II, CD19, or immunoglobulin M cross-linking. LMP2A effects were partially reversed in LMP1-converted cell lines. These results are compatible with LMP2A acting in latent B-lymphocyte infection to downmodulate LMP1 effects on cell growth or to inhibit induction of lytic EBV infection in specific human tissues following receptor ligation.