Fiorini Sylvie, Ooka Tadamasa
Laboratoire de Virologie Moléculaire, Virologie et Pathogenèse Humaine, FRE 3011, CNRS, Faculté de Médecine Laennec, Université Claude Bernard Lyon-1, Rue Guillaume Paradin, 69372, Lyon Cedex 08, France.
Virol J. 2008 Jun 4;5:70. doi: 10.1186/1743-422X-5-70.
Epstein-Barr virus (EBV) encodes two oncogenes, LMP1(Latent Membrane Protein-1) and BARF1 (BamH1-A Reading Frame-1). LMP1 belongs to latent gene family and BARF1 is considered so far as one of early gene family. However BARF1 oncogene was expressed highly in Nasopharyngeal (NPC) and gastric (GC) carcinoma as a type II latency, and in EBV-positive Akata cell and primary epithelial cell infected in vitro by EBV as type I latency. Its expression was also reported in Burkitt's lymphoma's biopsy frequent in Malawi in Africa as well as in nasal NK/T-cell lymphoma. We recently observed a massive secretion of BARF1 protein in serum and saliva of NPC patients. NPC-derived c666-1 epithelial cells also expressed and secreted BARF1 protein without other lytic genes expression. We asked whether this oncogene belongs to latent gene family. To investigate, we examined its transcriptional and translational expression in IB4 and Akata B cells where both cell lines belong to latent cell family. Transcriptional expression was analyzed by RT-PCR. As BARF1 protein is one of secreted proteins, its translational expression was analyzed by immunoblot after concentration of culture medium. Secreted BARF1 protein was futher purified by concanavalin A affinity column. BARF1 was transcribed in both EBV-positive AKATA and IB4 cells, and BARF1 protein was secreted from these latently infected human B cells. Its secretion does not depend EBV genome form in infected cells. Both episomal and integrated form of EBV genome were capable of expressing BARF1 gene. These results suggests that BARF1 is expressed in latent stage and increases its expression during lytic stage.
爱泼斯坦-巴尔病毒（EBV）编码两种癌基因，即潜伏膜蛋白1（LMP1）和BamH1-A读码框1（BARF1）。LMP1属于潜伏基因家族，而BARF1目前被认为是早期基因家族之一。然而，BARF1癌基因在鼻咽癌（NPC）和胃癌（GC）中以II型潜伏状态高表达，在EBV阳性的Akata细胞以及体外被EBV感染的原代上皮细胞中以I型潜伏状态高表达。在非洲马拉维常见的伯基特淋巴瘤活检组织以及鼻NK/T细胞淋巴瘤中也有其表达的报道。我们最近观察到NPC患者的血清和唾液中大量分泌BARF1蛋白。源自NPC的c666-1上皮细胞也表达并分泌BARF1蛋白，而无其他裂解基因的表达。我们想知道这种癌基因是否属于潜伏基因家族。为了进行研究，我们检测了它在IB4和Akata B细胞中的转录和翻译表达，这两种细胞系都属于潜伏细胞家族。通过逆转录聚合酶链反应（RT-PCR）分析转录表达。由于BARF1蛋白是分泌蛋白之一，通过对培养基浓缩后进行免疫印迹分析其翻译表达。分泌的BARF1蛋白通过伴刀豆球蛋白A亲和柱进一步纯化。BARF1在EBV阳性的AKATA和IB4细胞中均有转录，并且BARF1蛋白从这些潜伏感染的人B细胞中分泌出来。其分泌不依赖于感染细胞中EBV的基因组形式。EBV基因组的游离型和整合型都能够表达BARF1基因。这些结果表明，BARF1在潜伏阶段表达，并在裂解阶段增加其表达。
