The caterpillar Pseudoplusia includens (Walker, 1857) (Lepidoptera, Noctuidae), known as soybean looper, is a pest that has recently assumed greater importance in soybean in Brazil. Isolates of nucleopolyhedroviruses (NPVs) of this pest have been identified from cotton in Guatemala and soybean farms in Brazil, providing an interesting perspective of potential use of viral insecticide against the insect in lieu to chemical insecticides. With the objective to contribute to the characterization studies of this virus, morphological and molecular analyses and biological activity were carried out with seven P. includens viral isolates (I-A to I-G). Electron microscopy of viral samples, purified from macerated infected larvae, showed particles with typical morphology of the Baculoviridae family, genus Alphabaculovirus (Nucleopolyhedrovirus - NPV) presenting virions with only a single nucleocapsid per envelope (SNPV) occluded in a protein matrix, forming occlusion bodies (OB). This virus was then classified as P. includens single nucleopolyhedrovirus (PsinSNPV). OB particles analyzed in SDS-polyacrylamide gel showed an intense band corresponding in size to NPV polyhedrin protein. DNA restriction profiles of the PsinSNPV isolates showed differences in the fragment size and number suggesting the existence of genotypic variants, except between I-E and I-F profiles that were similar. Among the isolates tested for infectivity against P. includens, I-A, I-E and I-F were the most virulent. Survival times (ST(50)) varied according to viral concentration, with significant differences among isolates for the three higher concentrations.

BackgroundPseudoplusia includens single nucleopolyhedrovirus (PsinSNPV-IE) is a baculovirus recently identified in our laboratory, with high pathogenicity to the soybean looper, Chrysodeixis includens (Lepidoptera: Noctuidae) (Walker, 1858). In Brazil, the C. includens caterpillar is an emerging pest and has caused significant losses in soybean and cotton crops. The PsinSNPV genome was determined and the phylogeny of the p26 gene within the family Baculoviridae was investigated.ResultsThe complete genome of PsinSNPV was sequenced (Roche 454 GS FLX – Titanium platform), annotated and compared with other Alphabaculoviruses, displaying a genome apparently different from other baculoviruses so far sequenced. The circular double-stranded DNA genome is 139,132 bp in length, with a GC content of 39.3 % and contains 141 open reading frames (ORFs). PsinSNPV possesses the 37 conserved baculovirus core genes, 102 genes found in other baculoviruses and 2 unique ORFs. Two baculovirus repeat ORFs (bro) homologs, bro-a (Psin33) and bro-b (Psin69), were identified and compared with Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV) and Trichoplusia ni single nucleopolyhedrovirus (TnSNPV) bro genes and showed high similarity, suggesting that these genes may be derived from an ancestor common to these viruses. The homologous repeats (hrs) are absent from the PsinSNPV genome, which is also the case in ChchNPV and TnSNPV. Two p26 gene homologs (p26a and p26b) were found in the PsinSNPV genome. P26 is thought to be required for optimal virion occlusion in the occlusion bodies (OBs), but its function is not well characterized. The P26 phylogenetic tree suggests that this gene was obtained from three independent acquisition events within the Baculoviridae family. The presence of a signal peptide only in the PsinSNPV p26a/ORF-20 homolog indicates distinct function between the two P26 proteins.ConclusionsPsinSNPV has a genomic sequence apparently different from other baculoviruses sequenced so far. The complete genome sequence of PsinSNPV will provide a valuable resource, contributing to studies on its molecular biology and functional genomics, and will promote the development of this virus as an effective bioinsecticide.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1323-9) contains supplementary material, which is available to authorized users.

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The baculovirus, Chrysodeixis (formerly Pseudoplusia) includens nucleopolyhedrovirus (ChinNPV), is a new Alphabaculovirus pathogenic to Chrysodeixis includens. Here, we report the complete genome sequences of six ChinNPV isolates. The availability of these genome sequences will provide information on ChinNPV molecular genetics, promoting understanding of its pathogenicity, diversity, and evolution.

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Aos meus queridos familiares, pais, irmãos, avós, cunhados, sobrinhos, sogros, tios e primos pela preocupação demonstrada durante toda a realização do trabalho e pelo carinho, amor e dedicação proporcionados todos esses anos. À minha maravilhosa família construída ao lado do meu querido marido Fernando C. Fernandes, meu conselheiro e maior motivador, que suporta as recaídas e festeja as vitórias ao meu lado. Além disso, me presenteou com nosso bem mais valioso, meu bebê Guilherme, que se tornou minha maior inspiração. Ao Papai Saulo e Mamãe Rosana obrigada por sempre estarem presentes me apoiando, auxiliando nos momentos difíceis, incentivando quando faltam forças e sendo exemplos a quem procuro-me espelhar todos os dias. Ao meu querido irmão Allan Saul que me surpreende todos os dias pela sua resiliência e que me cativa com toda sua intensidade. Me proporcionou tanta alegria com o amor de titia dinda da nossa linda Emanuella e novamente me agrada com a oportunidade de fazer parte de sua família e conviver com minha cunhada Mariana e meu sobrinho de coração Davi. A minha mais nova família meus sogros Lauriana e Carlos Alberto e meus cunhados Vítor, Laura e Vívian obrigada por me receberem tão bem. Sou muito grata por toda atenção e carinho e estou muito feliz por compartilhar minha vida com mais vocês. A todos colegas e amigos, em especial, Briana, Daniela, Cristina e Lorena pela agradável convivência diária na Embrapa e UnB e pelos valiosos momentos de diversão.

We report the complete genomic sequences of seven viral isolates from the soybean looper (Chrysodeixis includens) from midwestern and southeastern Brazil. The genomes range from 138,760 to 139,637 bp in length with a G+C content of 39.2% and 140 open reading frames (ORFs).