Laboratory of Insect Virology, Cell Biology Department, University of Brasilia, Brasilia, DF 70910-900, Brazil; Postgraduate Program in Toxicological Biochemistry, Federal University of Santa Maria, Santa Maria, RS, 97105-900, Brazil.
Embrapa Soja, Londrina, PR 86001-970, Brazil.
Virus Res. 2022 Jul 15;316:198797. doi: 10.1016/j.virusres.2022.198797. Epub 2022 May 7.
The black armyworm Spodoptera cosmioides is a pest of increasing importance in Cry1Ac-Bt toxin crops and non-Bt crops of soybean and cotton in Brazil. Here we characterized a baculovirus isolated from extracts of S. cosmioides that died with symptoms of nuclear polyhedrosis. The putative novel virus exhibited polyhedral occlusion bodies (OBs) with virions containing multiple rod-shaped nucleocapsids, characteristic of alphabaculoviruses. The virus isolate was named Spodoptera cosmioides nucleopolyhedrovirus isolate CNPSo-72 (SpcoNPV-CNPSo-72). SpcoNPV-CNPSo-72 was lethal to third-instar S. cosmioides caterpillars but not to S. frugiperda under the tested viral concentrations. Moreover, SpcoNPV-CNPSo-72 contained a circular 147,763 bp long genome and a G + C content of 44.8% with 151 annotated ORFs (10 unique for baculovirus) and five homologous regions (hrs). The 38 currently defined baculovirus core genes were found in the SpcoNPV-CNPSo-72 genome. After phylogenetic analysis, the novel virus was found to be closely related to other members of Alphabaculovirus, especially to the Spodoptera-infecting viruses, which included Spodoptera eridania nucleopolyhedrovirus isolate 251, Spodoptera litura nucleopolyhedrovirus isolate II, Spodoptera exigua multiple nucleopolyhedrovirus isolate US-1, Spodoptera eridania nucleopolyhedrovirus isolate CNPSo-165, and Spodoptera frugiperda multiple nucleopolyhedrovirus isolate 19. Surprisingly, the new baculoviral genome was found to code for a putative arginine-associated tRNA gene with a predicted intronic sequence of 105 nt. The gene was found inside the bjdp CDS. Overall, baculoviruses are pathogens that lethally infect insect larvae and their study allows a better understanding of large DNA virus evolution, which provides important insights for the development and improvement of biological control agents.
黑褐色粘虫 Spodoptera cosmioides 是巴西 Cry1Ac-Bt 毒素作物和非 Bt 作物中大豆和棉花的一种日益重要的害虫。在这里，我们从表现出核多角体病症状而死亡的 S. cosmioides 提取物中分离出一种杆状病毒进行了特征描述。这种推定的新型病毒表现出多角体包埋体（OB），其中含有多个杆状核衣壳，这是α杆状病毒的特征。该病毒分离株被命名为 Spodoptera cosmioides 核多角体病毒分离株 CNPSo-72（SpcoNPV-CNPSo-72）。SpcoNPV-CNPSo-72 在测试的病毒浓度下对三龄 S. cosmioides 幼虫具有致死性，但对 S. frugiperda 没有致死性。此外，SpcoNPV-CNPSo-72 含有一个圆形的 147763bp 长基因组，G+C 含量为 44.8%，包含 151 个注释的 ORF（10 个是杆状病毒特有的）和 5 个同源区（hrs）。SpcoNPV-CNPSo-72 基因组中发现了 38 个目前定义的杆状病毒核心基因。在系统发育分析后，发现新型病毒与其他α杆状病毒成员密切相关，尤其是感染鳞翅目昆虫的病毒，包括斜纹夜蛾核多角体病毒分离株 251、甜菜夜蛾核多角体病毒分离株 II、甜菜夜蛾多角体病毒分离株 US-1、斜纹夜蛾核多角体病毒分离株 CNPSo-165 和美洲棉铃象甲多角体病毒分离株 19。令人惊讶的是，新的杆状病毒基因组被发现编码一个推定的精氨酸相关 tRNA 基因，其预测的内含子序列为 105nt。该基因位于 bjdp CDS 内。总的来说，杆状病毒是致死感染昆虫幼虫的病原体，对其研究可以更好地了解大型 DNA 病毒的进化，为生物防治剂的开发和改进提供重要的见解。
