Characterization of a new peritrophin homolog from Scylla paramamosain and its role in molting and immune defense

• Published in: Aquaculture Vol. 594; p. 741457
• Main Authors: Chen, Roushi, Yan, Jiaojiao, Li, Shuang, Wang, Ke-Jian, Chen, Fangyi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2025
• Subjects: Bacterial infection; Immune defense; Molting; Peritrophin; SpPT1; Bacterial infection; Peritrophin; Molting; Immune defense; SpPT1
• ISSN: 0044-8486
• DOI: 10.1016/j.aquaculture.2024.741457

Pathogenic infections are one of the main causes of molt failure and high mortality during molting on mud crab (Scylla paramamosain) farms. However, the molecular mechanisms associated with the immune defense during crab molting have not been clearly elucidated. Peritrophin, a classical chitin-binding protein, plays a key role in molting development and immunity of insects and crustaceans. In the present study, a new peritrophin homologous gene, SpPT1, was identified in S. paramamosain, and its full-length cDNA sequence was containing a single type II chitin-binding domain. During mud crab development, the SpPT1 gene was highly expressed at the zoea V stage, and its transcripts were significantly upregulated after molting compared to the pre-molt stage of juvenile crabs, particularly in the presence of bacterial exposure. A similar pattern was observed in the gills and subcuticular epidermis during molting in subadult crabs. Interestingly, this gene is regulated by 20E, a key steroid hormone during molting. In adult crabs, the highest expression of SpPT1 was detected in the midgut, followed by the stomach and hepatopancreas. This gene responded significantly to bacterial challenge in the hepatopancreas. Recombinant SpPT1 (rSpPT1) expressed in prokaryotes exhibited potent binding activity to chitin and several common aquatic pathogens, such as Vibrio alginolyticus, Vibrio parahaemolyticus, and Aeromonas hydrophila, as well as to four pathogen-associated molecular patterns (PAMPs). Notably, rSpPT1 promoted the phagocytosis of hemocytes in a dose-dependent manner in vitro, enhanced the clearance of V. alginolyticus from the hepatopancreas and gills, and significantly increased the survival of subadult S. paramamosain after bacterial infection in vivo. In addition, rSpPT1 markedly upregulated the expression of immune-related genes and enhanced the enzymatic activities of acid phosphatase and peroxidase in the hepatopancreas. Taken together, this study demonstrates that the peritrophin homolog SpPT1 might play a role in immune defense during molting, which provides new perspectives for the development of strategies to effectively control molt failure on crab farms. •SpPT1 gene was upregulated after molting and more significantly in response to bacterial challenge.•rSpPT1 exhibited potent binding activity to aquatic pathogens and PAMPs.•rSpPT1 promoted hemocyte phagocytosis in a dose-dependent manner.•rSpPT1 enhanced the bacterial clearance and crab survival.