Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Saiwai, Fuchu, Tokyo 183-8509, Japan.
Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Saiwai, Fuchu, Tokyo 183-8509, Japan.
J Invertebr Pathol. 2018 May;154:58-64. doi: 10.1016/j.jip.2018.03.016. Epub 2018 Mar 30.
A granulovirus (GV) that produces occlusion bodies (OBs) having an unusual morphology was found in an Adoxophyes sp. (Lepidoptera: Tortricidae) larva in a tea field in Miyazaki Prefecture, Japan. This isolate is considered to be a mutant of Adoxophyes orana granulovirus, designated AdorGV-M, because the nucleotide sequence of its genome is 99.7% identical to that of an English isolate of AdorGV, AdorGV-E. AdorGV-E produces typical ovocylindrical OBs that contain one occlusion-derived virus (ODV) per OB. On the other hand, AdorGV-M produces large cuboidal OBs, but the number of ODVs per OB was unknown. In this study, we quantified viral DNA in OBs of both AdorGV-E and -M, and determined the number of ODVs occluded in an OB of AdorGV-M. The two isolates had the same quantity of viral DNA in each OB, and we thus confirmed that one OB of AdorGV-M contains one ODV. To investigate the process of OB formation, fat body tissue of A. honmai larvae inoculated with each isolate was observed in a time course by transmission electron microscopy, and OB sizes were measured from micrographs. The main difference in OB formation was that AdorGV-M required more time to mature than AdorGV-E. In AdorGV-E, ODVs began to be covered from one end with an ovocylindrical OB at 96 h post-inoculation (hpi), and most of them were completely occluded at 120 hpi. Occlusion of AdorGV-M ODVs also began at 96 hpi, but the OB shape was cuboidal. Moreover, the OB size of AdorGV-M was similar to that of AdorGV-E at 120 hpi, but continued to grow until 192 hpi. AdorGV-M thus took more time to complete OB formation. Consequently, AdorGV-E has mature OBs with a diameter 0.22 μm and length 0.39 μm, but those of AdorGV-M are 1.34 × 1.23 μm.
在日本宫崎县的茶园中，从桃蛀果蛾（鳞翅目：卷蛾科）幼虫中发现了一种产生具有异常形态的包埋体（OBs）的颗粒体病毒（GV）。该分离株被认为是 Adoxophyes orana 颗粒体病毒的突变体，命名为 AdorGV-M，因为其基因组的核苷酸序列与英语分离株 AdorGV-E 完全相同。AdorGV-E 产生典型的卵圆柱状 OBs，每个 OB 中含有一个源自包埋的病毒（ODV）。另一方面，AdorGV-M 产生大型立方 OBs，但每个 OB 中 ODV 的数量未知。在这项研究中，我们量化了 AdorGV-E 和 -M 的 OB 中的病毒 DNA，并确定了 AdorGV-M 的 OB 中包埋的 ODV 数量。两种分离株在每个 OB 中具有相同数量的病毒 DNA，因此我们确认 AdorGV-M 的一个 OB 包含一个 ODV。为了研究 OB 形成的过程，我们通过透射电子显微镜观察接种了每种分离株的 A. honmai 幼虫的脂肪体组织，从显微照片中测量了 OB 的大小。OB 形成的主要区别在于，AdorGV-M 成熟所需的时间比 AdorGV-E 长。在 AdorGV-E 中，ODV 从接种后 96 小时（hpi）开始从一端开始用卵圆柱状 OB 覆盖，大多数在 120 hpi 时完全被包埋。AdorGV-M 的 ODV 包埋也从 96 hpi 开始，但 OB 形状为立方体形。此外，AdorGV-M 的 OB 大小在 120 hpi 时与 AdorGV-E 相似，但直到 192 hpi 仍在继续增长。因此，AdorGV-M 需要更多的时间来完成 OB 形成。结果，AdorGV-E 具有成熟的 OB，直径为 0.22 μm，长度为 0.39 μm，但 AdorGV-M 的 OB 为 1.34×1.23 μm。
