Interdepartmental Graduate Program in Microbiology and Institute for Integrative Genome Biology, Riverside Country, CA, USA.
Department of Botany and Microbiology, Faculty of Science, Alexandria University, Egypt.
J Gen Virol. 2022 Apr;103(4). doi: 10.1099/jgv.0.001737.
Ascoviruses are large double-stranded DNA insect viruses that destroy the nucleus and transform each cell into 20 or more viral vesicles for replication. In the present study we used RNA-sequencing to compare the expression of Trichoplusia ni ascovirus 6a1 (TnAV-6a1) core genes during the first week of infection, with emphasis on the first 48 h, comparing transcript levels in major somatic tissues (epidermis, tracheal matrix and fat body), the sites infected initially, with those of the haemolymph, where viral vesicles circulate and most replication occurs. By 48 h post-infection (p.i.), only 26 genes were expressed in somatic tissues at ≥5 log2 reads per kilobase per million, whereas in the haemolymph 48 genes were expressed at a similar level by the same time. Early and high expression of TnAV caspase-2-like gene occurred in all tissues, implying it is required for replication, but that it is probably not associated with apoptosis induction, which occurs in infections of Spodoptera frugiperda ascovirus 1 a (SfAV-1a), the ascovirus type species. Other highly expressed viral genes at 48 h p.i. in viral vesicles included a dynein-like beta chain and lipid-modifying enzymes, suggesting their importance to vesicle formation and growth as well as virion synthesis. Finally, as occurs in SfAV expression, we found bicistronic and tricistronic mRNA messages produced by TnAV.
杆状病毒是一种大型双链 DNA 昆虫病毒，它会破坏细胞核，并将每个细胞转化为 20 个或更多的病毒囊泡以进行复制。在本研究中，我们使用 RNA 测序比较了感染第一周内斜纹夜蛾杆状病毒 6a1（TnAV-6a1）核心基因的表达情况，重点比较了前 48 小时的情况，比较了主要体细胞组织（表皮、气管基质和脂肪体）、最初感染的部位与血淋巴中转录本水平的差异，病毒囊泡在血淋巴中循环，大部分复制发生在血淋巴中。在感染后 48 小时（p.i.），只有 26 个基因在体细胞组织中以每百万每千碱基对数至少 5 个对数的水平表达，而在同一时间，血淋巴中有 48 个基因以类似的水平表达。TnAV 半胱氨酸蛋白酶-2 样基因在所有组织中均早期和高表达，表明其对复制是必需的，但它可能与 Spodoptera frugiperda 杆状病毒 1a（SfAV-1a）感染中诱导的细胞凋亡无关，SfAV-1a 是杆状病毒的模式种。在感染后 48 小时，在病毒囊泡中高度表达的其他病毒基因包括动蛋白样β链和脂质修饰酶，这表明它们对囊泡形成和生长以及病毒粒子合成很重要。最后，与 SfAV 表达一样，我们发现 TnAV 产生双顺反子和三顺反子 mRNA 消息。
