Gao X, Tajima M, Sairenji T
School of Life Science, Faculty of Medicine, Tottori University, Nishimachi-86, Yonago, 683-8505, Japan.
Virology. 1999 Jun 5;258(2):375-81. doi: 10.1006/viro.1999.9748.
Nitric oxide (NO), a mediator of biological functions, has an antimicrobial activity against a variety of pathogens including viruses. In this study, we found that a constitutive, low level of inducible NO synthase (iNOS) mRNA was expressed in the EBV-infected gastric tissue-derived GT38 and GT39 cell lines, by analysis with the reverse transcription-polymerase chain reaction (RT-PCR) and Southern blotting. Treatment of these cells with a specific NOS inhibitor, NG-monomethyl-L-arginine (L-NMMA), induced the immediate-early, EBV transactivator gene BZLF1 protein ZEBRA, suggesting a significant increase in EBV reactivation by L-NMMA. Northern blotting demonstrated that BZLF1 and BRLF1 transcripts were also induced by 12-O-tetradecanoylphorbol-13 acetate (TPA). Meanwhile, constitutive expression of iNOS mRNA was inhibited by TPA. L-NMMA also enhanced TPA-induced expression of the BZLF1 gene. On the other hand, a NO donor, S-nitroso-N-acetylpenicillamine (SNAP), which releases NO in an aqueous solution, inhibited the TPA-induced BZLF1 gene expression in a dose-dependent manner at both mRNA and protein levels. These results demonstrated that NO is a regulatory factor in maintaining virus latency via inhibiting EBV reactivation in the infected epithelial cells.
一氧化氮（NO）作为一种生物功能介质，对包括病毒在内的多种病原体具有抗菌活性。在本研究中，通过逆转录聚合酶链反应（RT-PCR）和Southern印迹分析，我们发现在EBV感染的胃组织来源的GT38和GT39细胞系中，组成型低水平的诱导型一氧化氮合酶（iNOS）mRNA得以表达。用特异性一氧化氮合酶抑制剂NG-单甲基-L-精氨酸（L-NMMA）处理这些细胞，可诱导EBV早期反式激活基因BZLF1的蛋白ZEBRA表达，提示L-NMMA可显著增强EBV的激活。Northern印迹显示，12-O-十四烷酰佛波醇-13-乙酸酯（TPA）也可诱导BZLF1和BRLF1转录本表达。同时，TPA可抑制iNOS mRNA的组成型表达。L-NMMA还可增强TPA诱导的BZLF1基因表达。另一方面，一种在水溶液中释放NO的NO供体S-亚硝基-N-乙酰青霉胺（SNAP），在mRNA和蛋白质水平上均以剂量依赖方式抑制TPA诱导的BZLF1基因表达。这些结果表明，NO是通过抑制感染上皮细胞中EBV的激活来维持病毒潜伏状态的调节因子。
