Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA.
J Virol. 2013 Jan;87(2):912-22. doi: 10.1128/JVI.02415-12. Epub 2012 Nov 7.
Hantavirus pulmonary syndrome (HPS) is a severe respiratory disease characterized by pulmonary edema, with fatality rates of 35 to 45%. Disease occurs following infection with pathogenic New World hantaviruses, such as Andes virus (ANDV), which targets lung microvascular endothelial cells. During replication, the virus scavenges 5'-m(7)G caps from cellular mRNA to ensure efficient translation of viral proteins by the host cell cap-dependent translation machinery. In cells, the mammalian target of rapamycin (mTOR) regulates the activity of host cap-dependent translation by integrating amino acid, energy, and oxygen availability signals. Since there is no approved pharmacological treatment for HPS, we investigated whether inhibitors of the mTOR pathway could reduce hantavirus infection. Here, we demonstrate that treatment with the FDA-approved rapamycin analogue temsirolimus (CCI-779) blocks ANDV protein expression and virion release but not entry into primary human microvascular endothelial cells. This effect was specific to viral proteins, as temsirolimus treatment did not block host protein synthesis. We confirmed that temsirolimus targeted host mTOR complex 1 (mTORC1) and not a viral protein, as knockdown of mTORC1 and mTORC1 activators but not mTOR complex 2 components reduced ANDV replication. Additionally, primary fibroblasts from a patient with tuberous sclerosis exhibited increased mTORC1 activity and increased ANDV protein expression, which were blocked following temsirolimus treatment. Finally, we show that ANDV glycoprotein Gn colocalized with mTOR and lysosomes in infected cells. Together, these data demonstrate that mTORC1 signaling regulates ANDV replication and suggest that the hantavirus Gn protein may modulate mTOR and lysosomal signaling during infection, thus bypassing the cellular regulation of translation.
汉坦病毒肺综合征(HPS)是一种严重的呼吸疾病,其特征是肺水肿,死亡率为 35%至 45%。这种疾病是在感染了致病性新世界汉坦病毒后发生的,如安第斯病毒(ANDV),它靶向肺微血管内皮细胞。在复制过程中,病毒从细胞 mRNA 中掠夺 5'-m(7)G 帽,以确保病毒蛋白通过宿主细胞帽依赖性翻译机制得到有效翻译。在细胞中,雷帕霉素靶蛋白(mTOR)通过整合氨基酸、能量和氧气可用性信号来调节宿主帽依赖性翻译的活性。由于目前尚无针对 HPS 的批准的药物治疗方法,我们研究了 mTOR 途径抑制剂是否可以减少汉坦病毒感染。在这里,我们证明,用 FDA 批准的雷帕霉素类似物替西罗莫司(CCI-779)治疗可阻断 ANDV 蛋白表达和病毒粒子释放,但不阻断进入原代人微血管内皮细胞。这种作用是特异性的病毒蛋白,因为替西罗莫司治疗不会阻断宿主蛋白合成。我们证实替西罗莫司靶向宿主 mTOR 复合物 1(mTORC1),而不是病毒蛋白,因为 mTORC1 和 mTORC1 激活剂的敲低,但不是 mTOR 复合物 2 成分的敲低,可降低 ANDV 复制。此外,来自结节性硬化症患者的原代成纤维细胞表现出增加的 mTORC1 活性和增加的 ANDV 蛋白表达,这些表达在替西罗莫司治疗后被阻断。最后,我们表明 ANDV 糖蛋白 Gn 与感染细胞中的 mTOR 和溶酶体共定位。总的来说,这些数据表明 mTORC1 信号调节 ANDV 复制,并表明汉坦病毒 Gn 蛋白可能在感染过程中调节 mTOR 和溶酶体信号,从而绕过翻译的细胞调节。