Energy metabolism pathways control the fate of Sinonovacula constricta and induction of immune response under Vibrio parahaemolyticus challenge

Sinonovacula constricta, an important economic bivalve, is widely cultured on the southeast coast of China. However, its industrial development has been limited by diseases, especially vibriosis caused by Vibrio parahaemolyticus. In this study, we explored the key factors that determine the fate of razor clams under V. parahaemolyticus challenge using RNA-Seq, STEM and WGCNA. The transcriptome profiles of the razor clams were compared at different survival times after Vibrio infection, including clams that died within one to fifteen days and survived after fifteen days of treatment. The analysis of DEGs showed that genes in the C1qDC family, MAPK signaling pathway and Rap1 signaling pathway were significantly differentially expressed between the dying and survival groups in response to V. parahaemolyticus stimulation. The expression levels of genes involved in energy metabolism were positively correlated with the survival time by STEM analysis. The energy metabolism level of organisms may affect the intensity of the immune response and determine the fate of razor clams. In addition, the razor clams were divided into four periods according to death time and survival curve, including early stage (ScD1-ScD5), middle stage (ScD6-ScD10), late stage (ScD11-ScD15) and the survival group. In the early stage, an imbalance of apoptosis and the regeneration of blood cells are the main causes of razor clam death. In the middle stage, an energy metabolism level that is too low cannot meet the high energy needed for razor clam immunity, resulting in individual death. In the late stage, lysosome-related genes and C1qDC are downregulated significantly, slowing the removal of pathogenic bacteria and lipid metabolism. This study provided a comprehensive determination of razor clam fate at different stages in response to V. parahaemolyticus and emphasized the pivotal roles of energy metabolism and immunity in hosts under pathogen infection.