García-Serradilla Moisés, Risco Cristina
Cell Structure Laboratory, National Center for Biotechnology, CNB-CSIC, Campus UAM, Cantoblanco, 28049, Madrid, Spain.
Cell Structure Laboratory, National Center for Biotechnology, CNB-CSIC, Campus UAM, Cantoblanco, 28049, Madrid, Spain.
Virus Res. 2021 Sep;302:198444. doi: 10.1016/j.virusres.2021.198444. Epub 2021 May 4.
Drug repurposing is an important source of new antivirals because many compounds used to treat a variety of pathologies also hamper viral infections. Habitually, silver nanoparticles (AgNPs) have been used to treat bacterial and fungal infections and their antiviral properties have been also reported. In this work, we have studied the antiviral capacity of AgNPs in cells infected with Bunyamwera virus (BUNV), the prototype of the Bunyavirales order. This group of viruses contains important pathogens for humans, animals and plants. Incubation of BUNV-infected Vero cells with non-toxic concentrations of AgNPs, reduced the production of extracellular infectious viruses in up to three orders of magnitude. With a combination of imaging techniques, we have visualized the intracellular distribution of AgNPs in mock- and BUNV-infected cells and studied their effects on intracellular organelles. In mock-infected cells and at short times post-incubation, AgNPs were detected inside nuclei and mitochondria by transmission electron microscopy (TEM). At long times post-treatment, they accumulated inside lysosome-like organelles. Cell compartments did not exhibit any appreciable ultrastructural alterations after incubation with AgNPs. In BUNV-infected cells, AgNPs attached to extracellular virions, that showed a disrupted morphology. Inside cells, they were detected inside the nucleus, in mitochondria and around characteristic Golgi-associated, single-membrane spherules. These membranous structures are the replication organelles (ROs) of bunyaviruses and contain active viral replication complexes (VRCs). Compared to normal spherules that are round, compact and have an electron-dense core, spherules in AgNPs-treated cells were deformed and their core was electron-lucent. Interestingly, in BUNV-infected cells treated with the typical antiviral ribavirin (RBV), spherules with VRCs exhibit also an anomalous morphology and an electron-lucent core. Both AgNPs and RBV might interfere with BUNV-induced dismantling of cell nucleoli and with the intercellular propagation of large groups of virions, a mechanism of BUNV transmission observed for the first time in cultured cells. Our results point to silver nanoparticles as good candidates for antiviral therapy, either alone or in combination with other antiviral drugs, such as RBV-related compounds.
药物重新利用是新抗病毒药物的一个重要来源，因为许多用于治疗各种病症的化合物也能抑制病毒感染。习惯上，银纳米颗粒（AgNPs）已被用于治疗细菌和真菌感染，并且其抗病毒特性也有报道。在这项工作中，我们研究了AgNPs对感染布尼亚姆韦拉病毒（BUNV）的细胞的抗病毒能力，BUNV是布尼亚病毒目（Bunyavirales）的原型。这组病毒包含对人类、动物和植物的重要病原体。用无毒浓度的AgNPs孵育感染BUNV的Vero细胞，可使细胞外感染性病毒的产生减少多达三个数量级。通过多种成像技术的结合，我们可视化了AgNPs在未感染和感染BUNV的细胞中的细胞内分布，并研究了它们对细胞内细胞器的影响。在未感染的细胞中以及孵育后的短时间内，通过透射电子显微镜（TEM）在细胞核和线粒体中检测到AgNPs。在处理后的长时间内，它们积聚在溶酶体样细胞器内。用AgNPs孵育后，细胞区室未表现出任何明显的超微结构改变。在感染BUNV的细胞中，AgNPs附着在细胞外病毒粒子上，这些病毒粒子呈现出破坏的形态。在细胞内，在细胞核内、线粒体中以及特征性的高尔基体相关单膜小球周围检测到它们。这些膜结构是布尼亚病毒的复制细胞器（ROs），并含有活跃的病毒复制复合体（VRCs）。与正常的圆形、紧密且具有电子致密核心的小球相比，用AgNPs处理的细胞中的小球变形且其核心电子密度低。有趣的是，在用典型抗病毒药物利巴韦林（RBV）处理的感染BUNV的细胞中，带有VRCs的小球也呈现出异常形态且核心电子密度低。AgNPs和RBV都可能干扰BUNV诱导的细胞核仁解体以及大量病毒粒子的细胞间传播，这是在培养细胞中首次观察到的BUNV传播机制。我们的结果表明，银纳米颗粒无论是单独使用还是与其他抗病毒药物（如RBV相关化合物）联合使用，都是抗病毒治疗的良好候选药物。
