Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, College of Plant Protection, Hunan Agricultural University, Changsha, Hunan 410128, PR China.
Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, College of Plant Protection, Hunan Agricultural University, Changsha, Hunan 410128, PR China.
J Invertebr Pathol. 2022 Mar;189:107734. doi: 10.1016/j.jip.2022.107734. Epub 2022 Feb 19.
Ascoviruses are fatal double-stranded DNA viruses with a special pathogenesis in which cells are converted into vesicles with virions. Several closely related ascovirus isolates that shared more than 90% genomic DNA identity showed different pathogenic courses in previous studies. To investigate the pathogenic differences between the related ascovirus isolates, Heliothis virescens ascovirus 3i (HvAV-3i) and Heliothis virescens ascovirus 3j (HvAV-3j) were used to inoculate four noctuid pest species (Helicoverpa armigera, Mythimna separata, Spodoptera frugiperda, and Spodoptera litura), and the pathogenic indexes were recorded. The mortality of HvAV-3i infected H. armigera and S. frugiperda was approximately 60%, while the other HvAV-infected larvae had mortality rates above 90%. The maximum lethal dilution ratios of HvAV-3i in H. armigera, M. separata, S. frugiperda, and S. litura were 1.90 × 10, 1.90 × 10, 1.90 × 10, and 1.90 × 10 viral genome DNA copies/mL, respectively, while the ratios of HvAV-3j were 8.22 × 10, 8.22 × 10, 8.22 × 10, and 8.22 × 10 viral genome DNA copies/mL, respectively. Extended larval survival time was found in the HvAV-infected larvae; median survival time of the HvAV-infected larvae ranged from 13 to 19 days. An additional larval instar was found in HvAV-infected M. separata, S. frugiperda, and S. litura. Larval growth and food intake were significantly inhibited from 2 days post-infection (dpi) in the tested H. armigera, S. frugiperda, and S. litura after infection with HvAV-3i or HvAV-3j. The detoxification enzyme activity of host larvae was influenced after infection with HvAVs, and two different regulation patterns were detected, one in infected H. armigera and M. separata and the other in S. frugiperda and S. litura. The results obtained in this study provide insights into the pathogenic characteristics of ascoviruses.
杆状病毒是具有特殊发病机制的致命双链 DNA 病毒，其中细胞转化为带有病毒粒子的囊泡。先前的研究表明，几种密切相关的杆状病毒分离株具有超过 90%的基因组 DNA 同一性，但表现出不同的致病过程。为了研究相关杆状病毒分离株的致病差异，使用草地贪夜蛾杆状病毒 3i（HvAV-3i）和草地贪夜蛾杆状病毒 3j（HvAV-3j）接种四种夜蛾害虫物种（棉铃虫、粘虫、草地贪夜蛾和斜纹夜蛾），并记录致病指数。HvAV-3i 感染的棉铃虫和草地贪夜蛾死亡率约为 60%，而其他 HvAV 感染的幼虫死亡率超过 90%。HvAV-3i 在棉铃虫、粘虫、草地贪夜蛾和斜纹夜蛾中的最大致死稀释比分别为 1.90×10、1.90×10、1.90×10 和 1.90×10 病毒基因组 DNA 拷贝/mL，而 HvAV-3j 的比值分别为 8.22×10、8.22×10、8.22×10 和 8.22×10 病毒基因组 DNA 拷贝/mL。在 HvAV 感染的幼虫中发现了延长的幼虫存活时间；HvAV 感染的幼虫的中位存活时间范围为 13 至 19 天。在感染 HvAV 的粘虫、草地贪夜蛾和斜纹夜蛾中发现了一个额外的幼虫龄期。在感染 HvAV-3i 或 HvAV-3j 后，棉铃虫、草地贪夜蛾和斜纹夜蛾的幼虫生长和食物摄入从感染后 2 天（dpi）开始受到显著抑制。感染 HvAV 后，宿主幼虫的解毒酶活性受到影响，并检测到两种不同的调节模式，一种在感染的棉铃虫和粘虫中，另一种在草地贪夜蛾和斜纹夜蛾中。本研究的结果为杆状病毒的致病特征提供了新的认识。
