Although EBV-infected B cells have the potential for proliferation, they are effectively removed by the EBV-specific cytotoxic T cells (CTL). In the immunocompetent hosts, NK cells and antigen-specific CD8+ T-cells play an important role in inhibiting progression of primary EBV infection by granule-mediated cytotoxicity. The immune system is necessary to control the virus-induced transformation and the B-cell unlimited proliferation.