(-)-Epigallocatechin gallate (EGCG), abundant in green tea, is a potent anti-microbial and anti-tumor compound. This investigation used immunoblot, flow cytometry, microarray, and indirect immunofluorescence analyses to show that at concentrations exceeding 50 muM, EGCG inhibits the expression of Epstein-Barr virus (EBV) lytic proteins, including Rta, Zta, and EA-D, but does not affect the expression of EBNA-1. Moreover, DNA microarray and transient transfection analyses demonstrated that EGCG blocks EBV lytic cycle by inhibiting the transcription of immediate-early genes, thus inhibiting the initiation of EBV lytic cascade. (C) 2003 Elsevier Science (USA). All rights reserved.