Antiviral therapies that target herpesviruses are clinically important. Nelfinavir is a protease inhibitor that targets the human immunodeficiency virus (HIV) aspartyl protease. Previous studies demonstrated that this drug could also inhibit Kaposi’s sarcoma-associated herpesvirus (KSHV) production. Our laboratory demonstrated nelfinavir can effectively inhibit herpes simplex virus type 1 (HSV-1) replication. For HSV-1 we were able to determine that virus capsids were assembled and exited the nucleus but did not mature in the cytoplasm indicating the drug inhibited secondary envelopment of virions. For KSHV, we recently derived a tractable cell culture system that allowed us to analyze the virus replication cycle in greater detail. We used this system to further define the stage at which nelfinavir inhibits KSHV replication. We discovered that nelfinavir inhibits KSHV extracellular virus production. This was seen when the drug was incubated with the cells for 3 days and when we pulsed the cells with the drug for 1–5 min. When KSHV infected cells exposed to the drug were examined using ultrastructural methods there was an absence of mature capsids in the nucleus indicating a defect in capsid assembly. Because nelfinavir influences the integrated stress response (ISR), we examined the expression of viral proteins in the presence of the drug. We observed that the expression of many were significantly changed in the presence of drug. The accumulation of the capsid triplex protein, ORF26, was markedly reduced. This is an essential protein required for herpesvirus capsid assembly. Our studies confirm that nelfinavir inhibits KSHV virion production by disrupting virus assembly and maturation. This is likely because of the effect of nelfinavir on the ISR and thus protein synthesis and accumulation of the essential triplex capsid protein, ORF26. Of interest is that inhibition requires only a short exposure to drug. The source of infectious virus in saliva has not been defined in detail but may well be lymphocytes or other cells in the oral mucosa. Thus, it might be that a “swish and spit” exposure rather than systemic administration would prevent virion production.

中文翻译：

---

奈非那韦抑制卡波西肉瘤相关疱疹病毒蛋白表达和衣壳组装

针对疱疹病毒的抗病毒疗法在临床上很重要。奈非那韦是一种蛋白酶抑制剂，针对人类免疫缺陷病毒 (HIV) 天冬氨酰蛋白酶。先前的研究表明，这种药物还可以抑制卡波西肉瘤相关疱疹病毒（KSHV）的产生。我们的实验室证明奈非那韦可以有效抑制1型单纯疱疹病毒（HSV-1）的复制。对于 HSV-1，我们能够确定病毒衣壳已组装并离开细胞核，但未在细胞质中成熟，表明该药物抑制了病毒粒子的二次包膜。对于 KSHV，我们最近获得了一种易于处理的细胞培养系统，使我们能够更详细地分析病毒复制周期。我们使用该系统进一步确定奈非那韦抑制 KSHV 复制的阶段。我们发现奈非那韦抑制 KSHV 胞外病毒的产生。当药物与细胞一起孵育 3 天，以及当我们用药物脉冲细胞 1-5 分钟时，可以看到这一点。当使用超微结构方法检查暴露于药物的 KSHV 感染细胞时，细胞核中缺乏成熟的衣壳，表明衣壳组装存在缺陷。由于奈非那韦会影响综合应激反应（ISR），因此我们检查了该药物存在下病毒蛋白的表达。我们观察到，在药物存在下，许多基因的表达发生了显着变化。衣壳三链体蛋白 ORF26 的积累显着减少。这是疱疹病毒衣壳组装所需的必需蛋白质。我们的研究证实，奈非那韦通过破坏病毒组装和成熟来抑制 KSHV 病毒粒子的产生。这可能是因为奈非那韦对 ISR 的影响，从而影响蛋白质合成和必需的三链衣壳蛋白 ORF26 的积累。有趣的是，抑制作用只需要短时间接触药物即可。唾液中传染性病毒的来源尚未详细确定，但很可能是口腔粘膜中的淋巴细胞或其他细胞。因此，“漱口”暴露而不是全身给药可能会阻止病毒粒子的产生。