Sequencing-based network analysis provides a core set of genes for understanding hemolymph immune response mechanisms against Poly I:C stimulation in Amphioctopus fangsiao.

Aquatic viruses can spread rapidly and widely in seawater for their high infective ability. Polyinosinic-polycytidylic acid (Poly I:C), a viral dsRNA analog, is an immunostimulant that has been proved to activate various immune responses of immune cells in invertebrate. Hemolymph is a critical site that host immune response in invertebrates, and its transcriptome information obtained from Amphioctopus fangsiao stimulated by Poly I:C is crucial for understanding the antiviral molecular mechanisms of this species. In this study, we analyzed gene expression data in A. fangsiao hemolymph tissue within 24 h under Poly I:C stimulation and found 1082 and 299 differentially expressed genes (DEGs) at 6 and 24 h, respectively. Union set (1,369) DEGs were selected for subsequent analyses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were carried out for identifying DEGs related to immunity. Several significant immune-related terms and pathways, such as toll-like receptor signaling pathways term, inflammatory response term, TNF signaling pathway, and chemokine signaling pathway were identified. A protein–protein interaction (PPI) network was constructed for examining the relationships among immune-related genes. Finally, 12 hub genes, including EGFR , ACTG1 , MAP2K1 , and other nine hub genes, were identified based on the KEGG enrichment analysis and PPI network. The quantitative RT-PCR (qRT-PCR) was used to verify the expression profile of 12 hub genes. This research provides a reference for solving the problem of high mortality of A. fangsiao and other mollusks and provides a reference for the future production of some disease-resistant A. 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 blood immune responses in pathogen-infected invertebrate. [ABSTRACT FROM AUTHOR]