Lin C T, Kao H J, Lin J L, Chan W Y, Wu H C, Liang S T
Institute of Pathology, College of Medicine, National Taiwan University, Taipei, Republic of China.
Lab Invest. 2000 Aug;80(8):1149-60. doi: 10.1038/labinvest.3780123.
Many nasopharyngeal carcinoma (NPC) biopsy specimens contain Epstein-Barr virus (EBV). However, the response of NPC cells to EBV infection in vitro and in vivo is not well characterized. In this experiment we infected NPC cells with EBV particles through endocytosis of a complex of EBV immunoglobulin A (IgA) secretory component (SC) protein to observe the response of host cells to the foreign viral infection in vitro. We found that EBV particles were endocytosed and stabilized in NPC nuclei 24 hours after infection; the EBV genomes were then gradually decreased after serial passages within 3 to 4 weeks by the following pathway: the EBV genomes first moved toward the nuclear envelope from the center of the nucleus; after crossing the nuclear envelope, they moved into the cytoplasm and toward the plasma membrane and were discharged by exocytosis. At the 10th day of EBV infection, EBV-latent membrane protein-1 and Epstein-Barr nuclear antigen (EBNA)-1 protein expressions could be detected, but not EBV-viral capsid antigen. Observation of EBNA-1 protein and host growth factor and cytokine gene expressions in the weeks after incubation revealed that the EBNA-1 protein expression was decreased proportionally with decrease of EBV genome. The mRNA expression of epithelial growth factor receptor, transforming growth factor (TGF)-alpha, interleukin (IL)-1beta, IL-6, and granulocyte-macrophage colony-stimulating factor increased within 1 to 2 weeks after infection, and gradually recovered to the original level at 3 to 4 weeks, whereas the mRNAs of TGFbeta1, TGFbeta receptor type I (TGFbetaRI), TGFbetaR type II, IL-8, and tumor necrosis factor-alpha remained unchanged. It is concluded that in vitro EBV infection in NPC cells results in increase of certain growth factor and cytokine gene expressions in host cells. The change in gene expression returns to the original level approximately 3 to 4 weeks after infection because of exocytosis of EBV DNA by the infected cells through an unidentified mechanism.
许多鼻咽癌（NPC）活检标本中都含有爱泼斯坦-巴尔病毒（EBV）。然而，NPC细胞在体外和体内对EBV感染的反应尚未得到充分表征。在本实验中，我们通过EBV免疫球蛋白A（IgA）分泌成分（SC）蛋白复合物的内吞作用，用EBV颗粒感染NPC细胞，以观察宿主细胞在体外对这种外来病毒感染的反应。我们发现，感染后24小时，EBV颗粒被内吞并稳定在NPC细胞核中；随后，在3至4周内连续传代后，EBV基因组通过以下途径逐渐减少：EBV基因组首先从细胞核中心移向核膜；穿过核膜后，它们进入细胞质并移向质膜，然后通过胞吐作用排出。在EBV感染的第10天，可以检测到EBV潜伏膜蛋白-1和爱泼斯坦-巴尔核抗原（EBNA）-1蛋白的表达，但未检测到EBV病毒衣壳抗原。在培养后的几周内观察EBNA-1蛋白以及宿主生长因子和细胞因子基因的表达发现，EBNA-1蛋白表达随着EBV基因组的减少而成比例下降。上皮生长因子受体、转化生长因子（TGF）-α、白细胞介素（IL）-1β、IL-6和粒细胞-巨噬细胞集落刺激因子的mRNA表达在感染后1至2周内增加，并在3至4周时逐渐恢复到原始水平，而TGFβ1、I型TGFβ受体（TGFβRI）、II型TGFβ受体、IL-8和肿瘤坏死因子-α的mRNA则保持不变。得出的结论是，NPC细胞在体外感染EBV会导致宿主细胞中某些生长因子和细胞因子基因表达增加。由于受感染细胞通过一种未知机制将EBV DNA胞吐，感染后约3至4周基因表达变化恢复到原始水平。
