The immune response of fairy shrimp Branchinella kugenumaensis against Edwardsiella anguillarum infections by de novo transcriptome analysis

Abstract

To explore the immune defense mechanisms of the ancient crustacean fairy shrimp (B.kugenumaensis) and uncover antibacterial-related gene resources, the present study analyzed the pathological changes in B. kugenumaensis infected with E. anguillarum. Differential gene expression changes between the infected and uninfected groups were investigated through comparative transcriptome sequencing to elucidate the molecular responses to the infection. Under transmission electron microscopy, the intestinal mucosal structure of B. kugenumaensis was damaged, the microvilli disappeared, the number of mitochondria and endoplasmic reticulum increased, mitochondria vacuolated and arranged disordered. The transcriptome data indicated that a total of 250,520,580 clean reads were assembled into 66,502 unigenes, with an average length of 789 bp and an N50 length of 1326 bp. Following bacterial infection, approximately 2678 differentially expressed genes (DEGs) were identified, with 1732 genes upregulated and 946 genes downregulated. The detected DEGs related to immune responses, particularly involving apoptosis, lysosome, autophagy, phagosome, and MAPK signaling pathways. Moreover, 9 immunity-related genes with different expressions were confirmed by using real-time quantitative PCR (RT-qPCR). This study first reports the pathogenicity of E. anguillarum on B. kugenumaensis and speculates that immune effectors such as lysozyme and lectin, as well as apoptosis, lysosome, and the MAPK signaling pathway, play crucial roles in the innate immunity of fairy shrimp. These findings deepen our understanding of fairy shrimp immune regulatory mechanisms and provide a theoretical foundation for disease prevention and control.