Integration of Transcriptomic and Proteomic Analyses Reveals New Insights into the Regulation of Immune Pathways in Midgut of Samia ricini upon SariNPV Infection

SIMPLE SUMMARY: SariNPV is one of the main pathogens of Samia ricini and its infection of Samia ricini sericulture has caused significant economic losses to society. In this study, we aim to reveal the molecular mechanism of pathogen–host interactions in SariNPV-infected S. ricini through transcriptomic and proteomic analyses. Using RNA-sequencing and iTRAQ, we mapped the differentially expressed genes (DEGs) and proteins (DEPs) that are involved in the immune responses of S. ricini upon virus invasion. Based on our analyses, we identified specific DEGs and DEPs that are involved in various essential biological signaling pathways and immune-related pathways upon SariNPV invasion. These DEGs and DEPs play an important role in triggering host immune responses to pathogens. Our study provides molecular insights into host immune responses regarding pathogen invasion, in particular, the immune response mechanism and network of S. ricini in response to SariNPV infection. ABSTRACT: Samia ricini nucleopolyhedrovirus (SariNPV) is one of the main pathogens of S. ricini sericulture and its infection causes severe impacts on economic sericulture development. To explore and reveal the molecular mechanisms of S. ricini in response to SariNPV infection, we employed RNA sequencing (RNA-seq), adopting isobaric tags for relative and absolute quantitation (iTRAQ), and carried out combination analysis of the obtained differentially expressed genes (DEGs) and proteins (DEPs). Through transcriptome sequencing, a total of 2535 DEGs were detected, and with iTRAQ, 434 DEPs with significant expression difference were identified. Through correlation analysis, we found that the expression trends of 116 differentially expressed proteins were the same as those of differentially expressed genes (including 106 up-regulated and 10 down-regulated). Twenty-five key differentially expressed genes (proteins) involved in several signaling and immune related pathways (mainly involving Toll, Imd, Jak-STAT and Wnt signaling pathways, as well as other immune related pathways) were screened through real-time quantitative PCR. Our results, not only provide insights into the pathogenic mechanism of SariNPV infection in ricin silkworm and the immune response mechanism within the host, but also provide a significant contribution for identifying and preventing diseases caused by SariNPV.