Tenuivirus utilizes its glycoprotein as a helper component to overcome insect midgut barriers for its circulative and propagative transmission
Tenuivirus utilizes its glycoprotein as a helper component to overcome insect midgut barriers for its circulative and propagative transmission
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Tenuivirus 利用其糖蛋白作为辅助成分来克服昆虫中肠屏障，进行循环和繁殖传播
DOI：
10.1371/journal.ppat.1007655
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发表时间：
2019-03-01
期刊：
影响因子：
6.7
通讯作者：
Tao, Xiaorong
中科院分区：
文献类型：
--
作者：
Lu, Gang;Li, Shuo;Tao, Xiaorong
包括水稻条纹病毒（RSV）在内的许多持久性传播的植物病毒在世界范围内对作物生产造成严重损害。尽管许多报道表明，成功的昆虫介导的病毒传播取决于病毒与其昆虫载体之间的适当相互作用，但控制这种相互作用的机制仍然知之甚少。在这项研究中，我们使用RSV及其小褐飞虱（SBPH）载体作为工作模型，以阐明RSV病毒粒子进入SBPH中肠细胞进行病毒循环和繁殖传播的分子机制。我们已经确定，这种无包膜的细小病毒使用其非结构糖蛋白NSvc 2作为辅助组分来克服RSV复制和传播的中肠屏障。在这种糖蛋白的情况下，纯化的RSV病毒粒子不能进入SBPH中肠细胞。在RSV感染的细胞中，这种糖蛋白被加工成两种成熟蛋白：氨基末端蛋白（NSvc 2-N）和羧基末端蛋白（NSvc 2-C）。NSvc 2-N和NSvc 2-C都与RSV病毒体相互作用。结果表明，NSvc 2-N可以通过其N-糖基化位点直接结合到中肠腔表面。在识别后，中肠细胞经历内吞作用，随后RSV病毒体和NSvc 2区室化为早期内体，然后是晚期内体。NSvc 2-C在晚期内体内部的酸性条件下通过其高度保守的融合环基序触发细胞膜融合，导致RSV病毒体从内体释放到胞质溶胶中。综上所述，我们的研究结果首次表明，水稻细病毒利用其糖蛋白NSvc 2作为辅助组分，以确保其病毒粒子和SBPH中肠细胞之间的适当相互作用，以进行循环和繁殖传播。
Many persistent transmitted plant viruses, including rice stripe virus (RSV), cause serious damage to crop production worldwide. Although many reports have indicated that a successful insect-mediated virus transmission depends on a proper interaction between the virus and its insect vector, the mechanism(s) controlling this interaction remained poorly understood. In this study, we used RSV and its small brown planthopper (SBPH) vector as a working model to elucidate the molecular mechanisms underlying the entrance of RSV virions into SBPH midgut cells for virus circulative and propagative transmission. We have determined that this non-enveloped tenuivirus uses its non-structural glycoprotein NSvc2 as a helper component to overcome the midgut barrier(s) for RSV replication and transmission. In the absence of this glycoprotein, purified RSV virions were unable to enter SBPH midgut cells. In the RSV-infected cells, this glycoprotein was processed into two mature proteins: an amino-terminal protein (NSvc2-N) and a carboxyl-terminal protein (NSvc2-C). Both NSvc2-N and NSvc2-C interact with RSV virions. Our results showed that the NSvc2-N could bind directly to the surface of midgut lumen via its N-glycosylation sites. Upon recognition, the midgut cells underwent endocytosis followed by compartmentalization of RSV virions and NSvc2 into early and then late endosomes. The NSvc2-C triggered cell membrane fusion via its highly conserved fusion loop motifs under the acidic condition inside the late endosomes, leading to the release of RSV virions from endosomes into cytosol. In summary, our results showed for the first time that a rice tenuivirus utilized its glycoprotein NSvc2 as a helper component to ensure a proper interaction between its virions and SBPH midgut cells for its circulative and propagative transmission.