大多数细胞质复制的负链RNA病毒(NSV)通过捕获帽启动基因组转录。细胞质NSVs从中捕获加帽的RNA前导序列的宿主mRNA的来源仍然难以捉摸。较早的报道指出了细胞质RNA加工体(P体,PB),尽管有几个问题尚未解决。这里,Bunyavirales目植物和动物感染成员的核衣壳(N)蛋白,在casu番茄斑萎病毒(TSWV),水稻条纹病毒(RSV),Sinnombre病毒(SNV),克里米亚-刚果出血热病毒(CCHFV)和施马伦贝格病毒(SBV)已在其各自的植物和动物宿主的细胞中表达并定位。所有N蛋白都位于PBs以及应激颗粒(SGs),但广泛用于PB和SG的对接阶段。TSWV和RSVN蛋白也与RanGTP酶激活蛋白2(RanGAP2)共定位,核-细胞质穿梭因子,在核周区域,当与含有核定位信号的WPP结构域共表达时,部分在细胞核中。当PB和SG组分单独或同时沉默时,TSWV微型复制子的复制水平,通过GFP报告基因的表达来测量,从减少30%到增加四倍不等。在植物中RanGAP同源物沉默后,TSWV微型复制子的复制减少了75%。在体内帽供体竞争实验中,TSWV使用了去往PB和SG的转录本,还有从事翻译的功能成绩单。总之,结果暗示了一个更复杂的情况,除了PB,在细胞质复制和分段NSV的转录/帽捕获期间使用其他细胞质来源。
Most cytoplasmic-replicating negative-strand RNA viruses (NSVs) initiate genome transcription by cap snatching. The source of host mRNAs from which the cytoplasmic NSVs snatch capped-RNA leader sequences has remained elusive. Earlier reports have pointed towards cytoplasmic-RNA processing bodies (P body, PB), although several questions have remained unsolved. Here, the nucleocapsid (N) protein of plant- and animal-infecting members of the order Bunyavirales, in casu Tomato spotted wilt virus (TSWV), Rice stripe virus (RSV), Sin nombre virus (SNV), Crimean-Congo hemorrhagic fever virus (CCHFV) and Schmallenberg virus (SBV) have been expressed and localized in cells of their respective plant and animal hosts. All N proteins localized to PBs as well as stress granules (SGs), but extensively to docking stages of PB and SG. TSWV and RSV N proteins also co-localized with Ran GTPase-activating protein 2 (RanGAP2), a nucleo-cytoplasmic shuttling factor, in the perinuclear region, and partly in the nucleus when co-expressed with its WPP domain containing a nuclear-localization signal. Upon silencing of PB and SG components individually or concomitantly, replication levels of a TSWV minireplicon, as measured by the expression of a GFP reporter gene, ranged from a 30% reduction to a four-fold increase. Upon the silencing of RanGAP homologs in planta, replication of the TSWV minireplicon was reduced by 75%. During in vivo cap-donor competition experiments, TSWV used transcripts destined to PB and SG, but also functional transcripts engaged in translation. Altogether, the results implicate a more complex situation in which, besides PB, additional cytoplasmic sources are used during transcription/cap snatching of cytoplasmic-replicating and segmented NSVs.