Sequencing-based protein–protein interaction analysis provides a core set of immune gene for understanding white body immune response mechanisms against Poly I:C stimulation in Amphioctopus fangsiao

•This study integrates protein-protein interaction network into transcriptome analysis for the first time in cephalopods.•The result lays a function for further exploring invertebrate poly I:C stress at the molecular level.•It provides valuable gene resources for further study of the white body immune responses in pathogen-infected invertebrate. Pathogenic infections significantly limit the culture of marine organisms, such as cephalopods. However, there is a lack of immune information regarding cephalopods to address pathogen problems. Polyriboinosinic polyribocytidylic acid (Poly I:C), a synthetic virus-like molecule, can be recognized by the immune cells as pathogen-associated molecular patterns (PAMPs), and this process is often used to simulate the invasion of viruses. The white body is an immune and hematopoietic organ, and its RNA-seq information obtained from Amphioctopus fangsiao stimulated by Poly I:C is essential for understanding the antiviral immune response in this species. In this research, we performed transcriptome sequencing and bioinformatics analysis of A. fangsiao white body tissue within 24 h stimulated by Poly I:C. A large number of differentially expressed genes (DEGs) were detected in this study, including 2,613 and 8 DEGs at 6 h and 24 h, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used for searching immune-related terms and genes. A protein–protein interaction (PPI) network was constructed to identify the relationship between immune genes. Finally, the 20 hub genes including RAC1, MAPK14, PIK3CA and other seventeen hub genes were identified based on the network and pathway analyses, and we validated the accuracy of 20 hub genes using qRT-PCR. These hub genes mainly participated in PI3K-Akt signaling pathway, Chemokine signaling pathway and other signaling pathways, in addition to the ubiquitin family. These research results provided a valuable theoretical basis for researching A. fangsiao white body immunity and significantly improved our cognition about innate immunity of cephalopods.