State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, 430070, People's Republic of China.
Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, People's Republic of China.
Virol J. 2019 Feb 8;16(1):20. doi: 10.1186/s12985-019-1126-8.
Although the canonical function of viral coat protein (CP) is to encapsidate the viral genome, they have come to be recognized as multifunctional proteins, involved in almost every stage of the viral infection cycle. However, CP functions of Apple stem pitting virus (ASPV) has not been comprehensively documented. This study aimed to characterize the functions of ASPV CP and any functional diversification caused by sequence diversity of six ASPV CP variants and studied their biological, serological, pathogenic and viral suppressor of RNA silencing (VSR) functions.
Six ASPV CP variants that have previously been shown to belong to different subgroups were selected here to study their diversity functions. Agrobacterium mediated infiltration (Agroinfiltration) was used to express YFP-ASPV-CPs in Nicotiana. benthamiana and infect Nicotiana. occidental with PVX-ASPV-CPs in. Confocal microscopy was used to detect YFP-ASPV-CPs florescence. CPs expressed in Escherichia coli BL21 (DE3) were induced by IPTG.
In this study, we showed that recombinant CPs expressed in Escherichia coli BL21 (DE3) had different levels of serological reactivity to three anti-ASPV antibodies used to detect ASPV. Furthermore, fusion CPs with YFP (YFP-CPs) expressed in N. benthamiana cells differed in their ability to form aggregates. We also showed that ASPV isolates that harbour these CPs induced different biological symptoms on its herbaceous host N. occidentalis. At the same time, we found that all six CPs when expressed in PVX vector showed similar VSR activity and produced similar symptoms in N. occidentalis, despite their differences in amino acids.
Different ASPV isolates induced different symptoms in N. occidentalis, however, ASPV CP variants expressed in PVX vector showed the same symptoms in N. occidentalis plants. Also, we showed that ASPV CP variants has the same level of VSR activity, but they have different abilities to aggregate in N. benthamiana.
虽然病毒外壳蛋白（CP）的规范功能是包裹病毒基因组，但它们已被确认为多功能蛋白，参与病毒感染周期的几乎每个阶段。然而，苹果茎痘病毒（ASPV）的 CP 功能尚未得到全面记录。本研究旨在表征 ASPV CP 的功能，以及六个 ASPV CP 变体的序列多样性引起的任何功能多样化，并研究它们的生物学、血清学、致病性和病毒 RNA 沉默抑制子（VSR）功能。
选择以前已被证明属于不同亚群的六个 ASPV CP 变体来研究其多样性功能。使用农杆菌介导的浸润（Agroinfiltration）在 Nicotiana. benthamiana 中表达 YFP-ASPV-CPs，并使用 PVX-ASPV-CPs 在 Nicotiana. occidental 中感染。使用共聚焦显微镜检测 YFP-ASPV-CPs 的荧光。在 Escherichia coli BL21（DE3）中表达的 CP 用 IPTG 诱导。
在本研究中，我们表明在 Escherichia coli BL21（DE3）中表达的重组 CP 对用于检测 ASPV 的三种抗 ASPV 抗体具有不同程度的血清学反应性。此外，在 N. benthamiana 细胞中表达的与 YFP 融合的 CP（YFP-CPs）在形成聚集体的能力上有所不同。我们还表明，携带这些 CP 的 ASPV 分离株在其草本宿主 N. occidentalis 上引起不同的生物学症状。同时，我们发现，尽管它们的氨基酸不同，但在 PVX 载体中表达的这六种 CP 均表现出相似的 VSR 活性，并在 N. occidentalis 中产生相似的症状。
不同的 ASPV 分离株在 N. occidentalis 上引起不同的症状，然而，在 PVX 载体中表达的 ASPV CP 变体在 N. occidentalis 植物上表现出相同的症状。此外，我们表明 ASPV CP 变体具有相同水平的 VSR 活性，但它们在 N. benthamiana 中的聚集能力不同。
