Kinetics Of Epstein-Barr Virus (EBV) Latent And Lytic Protein Expression In EBV-Positive Burkitt, Epithelial And Lymphoblastoid Cells Upon Induction Of Lytic Cycle

Abstract

Epstein Barr virus (EBV) has latent and lytic infection cycles. We hypothesize that a subset of EBV latent proteins may be expressed and have functional roles in lytic cycle. We examined by Western blotting the expression of three latent proteins (EBNA1, EBNA2 and LMP1) and three lytic proteins (Zta, VCA-p18 and gp350/220) in Akata (Burkitt), AGS-BX1 (gastric carcinoma) and B95-8 (lymphoblastoid) cells at defined intervals between zero and 72 hours after lytic cycle activation with anti-IgG, suberoylanilide hydroxamic acid and TPA/sodium butyrate, respectively. EBNA1 was stably expressed in lytic cycle at the same level as that of latent cycle in all cell lines. EBNA2 was neither expressed in latent nor lytic phases of AGS-BX1 whilst it was expressed in Akata from 24 hours but downregulated in B95-8 from 48 hours post-induction. LMP1 was expressed in Akata from 16 hours and upregulated in B95-8 also from 16 hours but was never expressed in AGS-BX1. Zta was induced in Akata at 2 hours reaching maximal level at 24 hours whilst it was upregulated or induced in AGS-BX1 and B95-8 at 8 hours reaching maximal level at 48-72 hours postinduction. VCA-p18 and gp350/220 were induced at 8 hours in both Akata and AGS-BX1 rising to maximal level at 72 hours post-induction. These data suggest that EBNA2 and LMP1 may have function in lytic cycle of B but not epithelial cells. Simultaneous activation of Zta, VCA-p18 and gp350/220 in AGS-BX1 cells indicates different regulation of lytic cycle between epithelial and B cells.