Introduction of a precocious metamorphosis BmNPV infection in the latter half of the fifth instar silkworm larvae

The silkworm, Bombyx mori, is a complete metamorphosis insect, the model to study insect physiology and biochemistry. Bombyx mori nucleopolyhedrovirus (BmNPV) is a principal pathogen of the silkworm and its host range is restricted to silkworm larvae, requiring interaction with larvae to accomplish virus replication. Prothoracic glands (PGs) are a model for synthetic ecdysone with regulating insect growth and development. This study performed a transcriptome analysis of silkworm PGs after BmNPV infection. Transcriptome data were annotated with KEGG, GO, and shown to be of high quality by RT-qPCR. The spatial expression profiles of BmJing and BmAryl indicate that they may be specifically expressed in silkworm PGs. The RT-qPCR results of the DEGs in the PGs of BmNPV-infected larvae at 24, 48, and 72 h and at the developmental stages of days-6 and 7, comparing to day-3, reveal that the DEGs may be related to the BmNPV infection via promoting early maturation in the latter half of the silkworm fifth instar. This study is the first report on the identification of possible genes in PGs correlating with the precocious molting and metamorphosis of silkworm larvae under BmNPV infection in the latter half of the fifth instar. Our findings will help to address the interactions between BmNPV infection and host developmental response. This work provides a new perspective on BmNPV infection and host developmental response, as well as suggesting candidate genes for further research.