Characterization and genomic analyses of a novel alphabaculovirus isolated from the black armyworm, Spodoptera cosmioides (Lepidoptera: Noctuidae).

• We characterized a novel alphabaculovirus of Spodoptera cosmioides , called SpcoNPV-CNPSo-72. • SpcoNPV-CNPSo-72 presented polyhedral OBs and multiple-nucleocapsids per ODV. • The virus was able to kill S. cosmioides , but not S. frugiperda. • Its genome is 147,763 bp long with 151 ORFs and may represent a new species. • SpcoNPV-CNPSo-72 codes for a putative tRNA-Arg gene inside the bjdp gene. 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. [ABSTRACT FROM AUTHOR]