Whole-Transcriptome Analysis Reveals Potential CeRNA Regulatory Mechanism in against Infection.

() is a proto-ciliate parasite that infects marine fishes, including the cultured species (), causing disease and potential mortality. In host organisms, infection by parasites triggers an immune response that is modulated by regulatory elements including proteins and non-coding RNAs. In this study, the whole transcriptome RNA sequencing of gill tissue before and after infection with was performed to reveal the competitive endogenous RNA (ceRNA) regulatory network. Histomorphology revealed gill segment swelling and parasitic invasion in the infected group. The analysis identified 18 differentially expressed miRNAs (DEMs), 214 lncRNAs (DELs), 2501 genes (DEGs), and 7 circRNAs (DECs) in the infected group. Gene Ontology (GO) enrichment analysis revealed that these genes were notably enriched in the Wnt signaling pathway and mTOR signaling pathway. The co-expression networks (lncRNA/circRNA-miRNA-mRNA) were constructed based on correlation analysis of the differentially expressed RNAs. Further analysis suggested that the LOC105418663-circ_0000361-fru-miR-204a- ceRNA axis was potentially involved in the regulation of immune responses against infection. Finally, the expression levels of DEG, DEL, and DEM were validated. This study reveals the regulatory mechanism of a candidate ceRNA network, providing insights into the potential mechanism of ' infection with .