The recent epidemic of Zika virus (ZIKV) in the Americas and its association with fetal and neurological complications has shown the need to develop a treatment. Repurposing of drugs that are already FDA approved or in clinical development may shorten drug development timelines in case of emerging viral diseases like ZIKV. Initial studies have shown conflicting results when testing sofosbuvir developed for treatment of infections with another Flaviviridae virus, hepatitis C virus. We hypothesized that the conflicting results could be explained by differences in intracellular processing of the compound. We assessed the antiviral activity of sofosbuvir and mericitabine against ZIKV using Vero, A549, and Huh7 cells and measured the level of the active sofosbuvir metabolite by mass spectrometry. Mericitabine did not show activity, while sofosbuvir inhibited ZIKV with an IC₅₀ of ∼4 μM, but only in Huh7 cells. This correlated with differences in intracellular concentration of the active triphosphate metabolite of sofosbuvir, GS-461203 or 007-TP, which was 11–342 times higher in Huh7 cells compared to Vero and A549 cells. These results show that a careful selection of cell system for repurposing trials of prodrugs is needed for evaluation of antiviral activity. Furthermore, the intracellular levels of 007-TP in tissues and cell types that support ZIKV replication in vivo should be determined to further investigate the potential of sofosbuvir as anti-ZIKV compound.

最近在美洲流行的寨卡病毒（ZIKV）流行病及其与胎儿和神经系统并发症的关系表明，有必要开发一种治疗方法。在出现诸如ZIKV的新型病毒性疾病时，重新使用已获FDA批准或正在临床开发中的药物可能会缩短药物开发的时间表。最初的研究表明，在测试开发用于治疗另一种黄病毒科感染的索非布韦时，存在矛盾的结果。病毒，丙型肝炎病毒。我们假设可以用该化合物在细胞内加工过程中的差异来解释矛盾的结果。我们使用Vero，A549和Huh7细胞评估了sofosbuvir和mericitabine对ZIKV的抗病毒活性，并通过质谱法测量了活性sofosbuvir代谢产物的水平。Mericitabine没有显示活性，而Sofosbuvir则以IC ₅₀抑制ZIKV大约为4μM，但仅在Huh7细胞中。这与索非布韦，GS-461203或007-TP的活性三磷酸代谢产物的细胞内浓度差异有关，Huh7细胞中的三磷酸代谢产物的活性是Vero和A549细胞的11-342倍。这些结果表明，为评估抗病毒活性，需要仔细选择细胞系统以重新利用前药进行试验。此外，应该确定在体内支持ZIKV复制的组织和细胞类型中007-TP的细胞内水平，以进一步研究sofosbuvir作为抗ZIKV化合物的潜力。