Rankin J T, Eppes S B, Antczak J B, Joklik W K
Department of Microbiology and Immunology, Duke University Medical Center, Durham, North Carolina 27710.
Virology. 1989 Jan;168(1):147-58. doi: 10.1016/0042-6822(89)90413-3.
We have examined the mechanism by which ribavirin inhibits the multiplication of reovirus. At a concentration of 12.5 microM (3 micrograms/ml) ribavirin inhibits viral multiplication, ssRNA formation, dsRNA formation, and protein synthesis by about 90%; when much higher concentrations are used for brief periods of time, the primary target of ribavirin is seen to be viral ssRNA synthesis. When the effect of ribavirin triphosphate (RTP) was tested on the in vitro transcription by cores of the dsRNA genome segments into plus-stranded RNA, elongation, that is, the formation of intact mRNA molecules, was found to be inhibited to the greatest extent; initiation was at least 2.5 times less sensitive, and cap formation and methylation were almost unaffected. The inhibition of elongation and initiation was not competitive with respect to any of the four nucleoside triphosphates. Remarkably, the transcription of plus strands into minus strands by immature reovirus particles (the replicase reaction) was insensitive to RTP. A model is proposed that envisages RTP binding to a site close to the catalytic site of the transcriptase. This binding is postulated to inhibit the helicase function of the transcriptase and lower its affinity for template RNA so that the likelihood of premature termination is greatly increased. The helicase activity is not, of course, necessary for the transcription of plus strands into minus strands, which would account for the differential sensitivity of the transcriptase and the replicase to RTP.
我们研究了利巴韦林抑制呼肠孤病毒增殖的机制。在浓度为12.5微摩尔（3微克/毫升）时，利巴韦林可抑制病毒增殖、单链RNA形成、双链RNA形成以及蛋白质合成约90%；当使用更高浓度并作用较短时间时，利巴韦林的主要作用靶点被认为是病毒单链RNA合成。当测试利巴韦林三磷酸酯（RTP）对双链RNA基因组片段核心体外转录为正链RNA的影响时，发现延伸过程，即完整mRNA分子的形成，受到的抑制程度最大；起始过程的敏感性至少低2.5倍，帽形成和甲基化几乎不受影响。延伸和起始的抑制对四种核苷三磷酸中的任何一种都不具有竞争性。值得注意的是，未成熟呼肠孤病毒颗粒将正链转录为负链（复制酶反应）对RTP不敏感。提出了一个模型，设想RTP与转录酶催化位点附近的一个位点结合。据推测，这种结合会抑制转录酶的解旋酶功能并降低其对模板RNA的亲和力，从而大大增加过早终止的可能性。当然，解旋酶活性对于正链转录为负链并非必需，这可以解释转录酶和复制酶对RTP的不同敏感性。
