Transcription of the Epstein-Barr Virus Lytic Cycle Activator BZLF-1 During Oxidative Stress Induction

While latent Epstein-Barr virus infection can be in vitro reactivated by various reagents such as 12-0-tetradecanoylphorbol-13-acetate and calcium ionophore, relatively little is known about in vivo physiological and biochemical factors implicated in this reactivation. Previous studies have described an association between oxidative stress and Epstein-Barr virus infection. In this present study, we investigated the effect of oxidative stress inductors: H₂O₂ and FeSO₄ on reactivation of EBV through BZLF-1 gene expression. Oxidative stress was induced in Raji cell line with 0.2 mM H₂O₂ or with 0.1 mM FeSO₄, and assessed by malondialdehyde level determination, as well as superoxide dismutase and catalase genes expression. Simultaneously, the expression of Epstein-Barr virus immediate-early gene BZLF-1 was analyzed by RT-PCR after 6, 12, 24, 36, and 48 h after H₂O₂ or FeSO₄ treatment. Oxidative stress was evidenced in the Raji cell line by high MDA level as well as superoxide dismutase and catalase genes up-regulation. The transcripts of BZLF-1 were detected from 6 h after 30 min of H₂O₂ or FeSO₄ treatment and maintained until 48 h. These results strongly suggest that oxidative stress contributes to the reactivation of EBV lytic cycle, through induction of BZLF-1 gene expression, a process that may play an important role in the pathogenesis of EBV-associated diseases.