Role of immunoglobulin M in Trachinotus ovatus defense against Cryptocaryon irritans infection

Huicheng Wu; Shu Tang; Yipei Lu; Yihao Cen; Yiyang Deng; Yanwei Li; Xueming Dan; Zequan Mo

doi:10.1016/j.ijbiomac.2025.145556

Role of immunoglobulin M in Trachinotus ovatus defense against Cryptocaryon irritans infection

Int J Biol Macromol. 2025 Jun 25:145556. doi: 10.1016/j.ijbiomac.2025.145556. Online ahead of print.

Authors

Huicheng Wu¹, Shu Tang², Yipei Lu¹, Yihao Cen¹, Yiyang Deng¹, Yanwei Li¹, Xueming Dan³, Zequan Mo⁴

Affiliations

¹ University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, Guangdong Laboratory for Lingnan Modern Agriculture, College of Marine Sciences, South China Agricultural University, Guangzhou, China.
² Guangdong Animal Disease Prevention and Control Center (Guangdong Animal Health and Quarantine Institute), Guangzhou 510665, China.
³ University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, Guangdong Laboratory for Lingnan Modern Agriculture, College of Marine Sciences, South China Agricultural University, Guangzhou, China. Electronic address: dxm72@scau.edu.cn.
⁴ University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, Guangdong Laboratory for Lingnan Modern Agriculture, College of Marine Sciences, South China Agricultural University, Guangzhou, China. Electronic address: mzq1990@scau.edu.cn.

PMID: 40578639
DOI: 10.1016/j.ijbiomac.2025.145556

Abstract

Cryptocaryon irritans, a marine parasitic protozoan, poses a significant threat to marine teleosts, including golden pompano (Trachinotus ovatus) species. Studies show that T. ovatus can develop specific immunity following C. irritans exposure. However, the precise mechanisms underlying the immune response remain unclear. Therefore, this study aims to investigate the effects of an immunization protocol in pompano, involving their exposure to non-lethal doses of theronts, achieving a 44.6 % reduction in infection rates compared to the controls. Parasite-specific Immunoglobulin M (IgM) levels increased in the serum, mucus, and explant supernatants of immunized pompano, with significantly enhanced IgM-positive signals in the skin and spleen, indicating systemic and mucosal immunity activation. Furthermore, the developed immunity against C. irritans in immunized pompano was compromised by injecting rabbit polyclonal antibodies (pAbs) against pompano IgM, resulting in decreased parasite-specific IgM levels, reduced IgM-positive signal, and higher tomont counts. In conclusion, this study demonstrates the induction of IgM immune response in pompano following C. irritans exposure and underscores the critical role of IgM in defense against this pathogen, offering a theoretical foundation for future vaccine development.

Keywords: Cryptocaryon irritans; Immune response; Immunoglobulin M (IgM); Polyclonal antibodies; Teleosts; Trachinotus ovatus.