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Cycle productif du virus d‘Epstein‐Barr : rôle de la protéine virale EB1 dans l‘activation du cycle productif et interactions protéine EB1‐cellules hôte Volume 7, issue 2, Mars 2003

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Authors
U412 Inserm, ENS‐Lyon, 46 allée d‘Italie, 69364 Lyon cedex 07 E‐mail : hgruffatens‐lyon.fr

In B lymphocytes induced to proliferate in vitro by EBV, extra‐chromosomal viral episomes packaged in chromatin, persist in the nucleus and there is no productive cycle. A switch from this latency to the productive cycle is observed after induced expression of two EBV transcription factors, EB1 and R which are products of the BZLF1 and BRLF1 genes respectively. This review focuses both on the function of these two proteins and on the regulation of their expression. We present a model in which latency is determined primarily by a specific and local recruitment of class II HDAC (Histone Deacetylase) to the BZLF1 gene promoter by MEF2‐D. The switch from latency to the productive cycle could be due in part to postranslational modifications of MEF2 proteins and changes in the local acetylation state of the chromatin, following various transduction signals. Then, in combination with R, EB1 will activate all the viral early genes. Furthermore, EB1 is directly involved in activation of the EBV replication origin ( OriLyt) and may also have pleiotropic effects on various cellular pathways, which could be relevant to EBV‐associated pathologies.