Histopathology, immunoenzyme activity and transcriptome analysis of immune response in silver pomfret infected by
Guanlin Wang1, Jiabao Hu2, Man Zhang1
1School of Marine Sciences, Ningbo University, Ningbo, China; Key Laboratory of Applied Marine Biotechnology, Ningbo University, Ministry of Education, Ningbo, China; Key Laboratory of Marine Biotechnology of Zhejiang Province, Ningbo University, Ningbo, China.
Abstract:
Cryptorchidism irritant (CI) infection is a major problem in the culturing process of silver pomfret (Pampus argenteus), which can result in rapid and massive death. However, there is limited information available on the immune response of silver pomfret infected by CI. To address this gap, we sampled naturally infected fish and observed milky white translucent oval CI trophozoites on the gills, body surface, and fin rays. Histological analysis showed that CI infection led to vacuolation of epithelial cells and a decrease in blood cells in the gills. We also performed transcriptome profiling of the gill, kidney complex, and spleen, generating 399,616,194 clean reads that assembled into 101,228 unigenes, which were annotated based on public databases. We detected 14,369 differentially expressed genes, and selected several key immune-related genes for further validation using RT-qPCR. The Graft-versus-host pathway and Allograft rejection pathway were enriched in the gills, leading to inflammation and ulceration. CI infection activated the immune system, increasing levels of interleukin-1 beta and MHC class II antigen, and also activated innate and acquired immune genes in silver pomfret. Furthermore, we measured the activities of five immune-related enzymes (SOD, AKP, CAT, CSH and ACP), which all increased to varying degrees after CI infection. Our findings enhance our understanding of the immune response of fish to parasitic infection and may contribute to the development of strategies to prevent high mortality in CI-stimulated fish in aquaculture.
Insights
Cryptorchidism irritant (CI) infection causes significant silver pomfret mortality. This study reveals CI activates fish immune responses, including inflammation and increased immune gene expression, offering insights for aquaculture disease management.
Area of Science:
- Aquatic animal immunology
- Fish pathology
- Parasitology
Background:
- Cryptorchidism irritant (CI) infection poses a severe threat to silver pomfret (Pampus argenteus) aquaculture, leading to substantial fish losses.
- Limited knowledge exists regarding the specific immune mechanisms silver pomfret employ to combat CI infection.
Purpose of the Study:
- To investigate the immune response of silver pomfret to Cryptorchidism irritant (CI) infection.
- To identify key molecular pathways and immune markers involved in the fish's defense against CI.
Main Methods:
- Observation of naturally CI-infected silver pomfret, including histological analysis of infected tissues (gills).
- Transcriptome profiling of gill, kidney complex, and spleen to identify differentially expressed genes.
- Validation of key immune genes using RT-qPCR and measurement of immune-related enzyme activities.
Main Results:
- CI infection induced gill pathology, including epithelial cell vacuolation and decreased blood cells.
- Transcriptome analysis revealed significant immune pathway enrichment (e.g., Graft-versus-host, Allograft rejection) and identified differentially expressed immune genes.
- Elevated levels of interleukin-1 beta, MHC class II antigen, and increased activities of immune enzymes (SOD, AKP, CAT, CSH, ACP) were observed post-infection.
Conclusions:
- CI infection triggers a robust immune response in silver pomfret, involving both innate and acquired immunity.
- Understanding these immune responses provides a foundation for developing strategies to mitigate CI-induced mortality in farmed fish.
- This research contributes crucial data to fish immunology and aquaculture disease management.
