Pathological and miRNA-mRNA Analyses Provide New Insights into the Immune Response of Clams to Vibrio Infection

Abstract

Manila clam plays a crucial role in China’s marine aquaculture industry. However, frequent vibriosis outbreaks severely hinder sustainable and healthy development of the shellfish aquaculture industry. This study indicated markedly decreased clam survival rates after 48 h of Vibrio alginolyticus challenge. Gill and hepatopancreas damage was investigated through histological observation. The activity of lysozyme in the gills and hepatopancreas peaked at 12 and 24 h, respectively. V. alginolyticus showed a maximum bacterial load in the gills and hepatopancreas at 12 and 24 h, respectively. Additionally, transcriptome sequencing of hepatopancreas revealed ten differentially expressed miRNAs in Va and Cn after 48 h infection with V. alginolyticus, corresponding to 100 target genes, with eight upregulated and two downregulated DE miRNAs. Gene ontology (GO) enrichment analysis identified 50 known miRNAs and 111 novel miRNAs, thereby predicting a total of 1840 target genes. KEGG analysis revealed significant changes in multiple signaling pathways, involving lysosomes, apoptosis, amino acid metabolism, and endocytosis, in response to V. alginolyticus stimulation. This study provided new information regarding the immune regulation mechanisms of R. philippinarum in response to V. alginolyticus stress.