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

LMP2A is expressed in latent Epstein-Barr virus (EBV) infection and in teracts with LMP1 and members of the src tyrosine kinase family in the plasma membrane. Since tyrosine kinases mediate receptor-induced chan ges in intracellular free calcium, the effect of LMP2A on receptor-med iated intracellular calcium mobilization was evaluated by stably expre ssing LMP2A in an EBV-negative Burkitt tumor cell line (BJAB) or in LM P1-converted BJAB cells. LMP2A significantly blocked calcium mobilizat ion following class II, CD19, or immunoglobulin M cross-linking. LMP2A effects were partially reversed in LMP1-converted cell lines. These r esults are compatible with LMP2A acting in latent B-lymphocyte infecti on to downmodulate LMP1 effects on cell growth or to inhibit induction of lytic EBV infection in specific human tissues following receptor l igation.