The B cell-immortalizing functions of Epstein-Barr virus

The Epstein-Barr virus (EBV) is a human B lymphotropic herpesvirus carried in a persistent state by over 90% of the world's population. Primary infection occurs by the oral route, generally in early childhood, and is asymptomatic. When infection is delayed until adolescence or later, infectious mononucleosis results in approximately 50% of cases. Although it has been postulated that the oropharynx provides a reservoir where circulating B cells can be infected during transit through this anatomical site, evidence has been presented suggesting that EBV can also persist in the B cell (Gratama et al., 1988; Yao et al., 1989 a, b). Cellular immune mechanisms are believed to be of the greatest importance in the suppression of infected cell proliferation, and the balance between continual infection and suppression results in a life-long carrier state (reviewed by Rickinson, 1986).