Recently, the genome of Spodoptera litura granulovirus (SlGV) which encodes 133 putative open reading frames (ORFs) was completely sequenced. In this study, to screen novel insecticidal genes of SlGV, we first constructed an advanced plasmid capture system, pPCS-TPI, which contains not only pUC19 ori and ampicillin resistance gene but also Autographa californica nucleopolyhedrovirus (AcMNPV) ORF603 and ORF1629 homologous region between Tn7L and Tn7R. In order to introduce genomic segments of SlGV into the genome of AcMNPV, genomic DNA of SlGV was digested with EcoRI and self-ligated. These self-ligated segments were in vitro transposed with the pPCS-TPI donor by the help of TnsABC* transposase. By this, 10 EcoRI-digested genomic segments of the SlGV were cloned, and these clones were co-transfected with the bApGOZA DNA into sf9 cells to generate corresponding recombinant virus, respectively. The resulting recombinant viruses harboring genomic segments of the SlGV could be used to investigate the insecticidal activity and/or other functions originated from the introduced genomic segments of the SlGV.

The genome of a granulovirus isolated from the tobacco cutworm, Spodoptera litura, was completely sequenced. The nucleotide sequence of the Spodoptera litura granulovirus (SlGV) genome was 124,121 bp long, with a 61.2% A+T content and contained 133 putative open reading frames (ORFs) of 150 nucleotides or larger. The 133 putative ORFs covered 86.3% of the genome. Among these, 29 ORFs were conserved in most completely sequenced baculovirus genomes, 35 were granuloviruses (GVs)-specific, and 60 were present in some NPVs and/or GVs. Especially, we proved that there were 9 SlGV-specific ORFs by RT-PCR. When the phylogenic relationship was analyzed using the nucleotide sequence of granulin gene, SlGV was most closely related to Trichoplusia ni granulovirus (TnGV) and Xestiac-nigrum granulovirus (XcGV) which were belonged to Type-I granulovirus. Comparative analysis of gene organization of the SlGV genome with those of other baculoviruses were carried out using blast matrix and gene order diagram.

The nucleotide sequence of the Spodoptera litura granulovirus (SlGV) genome was determined and analysed. It was 124,121 bp long, with a 61.2% A+T content and contained 133 putative open reading frames (ORFs) of 150 nucleotides or larger. The 133 putative ORFs covered 86.3% of the genome. Among these, 29 ORFs were conserved in most completely sequenced baculovirus genomes, 44 were granuloviruses (GVs)-specific, 4 were nucleopolyhedroviruses (NPVs)-specific, and 56 were present in some NPVs and/or GVs. Especially, we proved that there were 9 SlGV-specific ORFs in 44 GV-specific ORFs by RT-PCR. Chitinase and cathepsin genes involved in the liquefaction of the infected hostwere not found in the SlGV genome, which explains why SlGV-infected insects do not degrade in a typical manner. When the phylogenic relationship was analyzed using the nucleotide sequence of granulin gene, SlGV was most closely related to Trichoplusia ni granulovirus (TnGV) and Xestia c-nigrum granulovirus (XcGV) which were belonged to TypeI granulovirus.