Feed Status and Skin Injury Modulate Immunopathology, Global Gene Expression, and Survival in Channel Catfish During Virulent Aeromonas hydrophila Infection

Authors: SOKU, YESUTOR - Tuskegee University; Lange, Miles; Abernathy, Jason; SANKAPPA, NITHIN - Orise Fellow; Shoemaker, Craig; HAYDEN, KARL - Tuskegee University; Andersen, Linnea; PHILLIPS, IDA - North Carolina Veterinary Diagnostics Laboratory; NASHAR, TOUFIC - Tuskegee University; SAMUEL, TEMESGEN - Tuskegee University; MOHAMED, ABDELRAHMAN - Tuskegee University

Submitted to: Frontiers in Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2025
Publication Date: 7/22/2025
Citation: Soku, Y., Lange, M.D., Abernathy, J.W., Sankappa, N., Shoemaker, C.A., Hayden, K., Andersen, L.K., Phillips, I., Nashar, T., Samuel, T., Mohamed, A. 2025. Feed Status and Skin Injury Modulate Immunopathology, Global Gene Expression, and Survival in Channel Catfish During Virulent Aeromonas hydrophila Infection. Frontiers in Immunology. 16(2025): Article 1642531.
DOI: https://doi.org/10.3389/fimmu.2025.1642531

Interpretive Summary: Virulent Aeromonas hydrophila is a major pathogen in channel catfish (Ictalurus punctatus), that causes motile Aeromonas septicemia (MAS). MAS results in significant economic losses to US and world aquaculture. We investigated the effect of feeding status and skin integrity on the host immune response, disease survival, and gastrointestinal pathology following a vAh challenge. Using a bath immersion model, channel catfish were divided into four treatment groups—fin clipped and fed (FCF), fin clipped but not fed (FCN), not fin clipped but fed (NCF), and not fin clipped nor fed (NCN) alongside non-challenged control groups. The FCF and NCF groups were fed 2 h prior to the challenge, but the FCN and NCN groups were not. Survival rates were lowest in the FCF and FCN groups (30% and 23% survival, respectively), suggesting that both feeding and skin damage contributed to disease severity. Histopathological analyses revealed more severe intestinal and gastric lesions in fed groups, characterized by epithelial necrosis, hemorrhage, and edema. Gene ontology enrichment highlighted distinct immune activation patterns between fed and unfed groups, with enhanced pathogen recognition and pro-inflammatory responses in unfed fish. These findings suggest feeding exacerbates disease pathology because post-prandial blood flow to the gastrointestinal tissues facilitates pathogen proliferation and transient immune suppression, whereas fasting promotes early immune activation. The data suggest that withholding feed may be the best course of action during an active infection however this recommendation has had mixed results with other catfish-relevant pathogens, specifically Edwardsiella ictaluri and Flavobacterium covae.

Technical Abstract: Virulent Aeromonas hydrophila is a major pathogen in channel catfish (Ictalurus punctatus), that causes motile Aeromonas septicemia and significant economic losses. We investigated the effect of feeding status and skin integrity on the host immune response, disease survival, and gastrointestinal pathology following a vAh challenge. Using a bath immersion model, channel catfish were divided into four treatment groups: fin clipped and fed (FCF), fin clipped but not fed (FCN), not fin clipped but fed (NCF), and not fin clipped nor fed (NCN) alongside non-challenged control groups The FCF and NCF groups were fed 2 h prior to the challenge, but the FCN and NCN groups were not. Survival analysis, histopathological assessment, and RNA sequencing were conducted across groups at different time intervals throughout the vAh challenge. Survival rates were lowest in the FCF and FCN groups (30% and 23% survival, respectively), suggesting that both feeding and skin damage contributed to disease severity. Histopathological analyses revealed more severe intestinal and gastric lesions in fed groups, characterized by epithelial necrosis, hemorrhage, and edema. Transcriptomic analysis among the groups identified significant differentially expressed genes associated with inflammation, apoptosis, and metabolic stress, with notable upregulation of interleukin 1-beta (IL-1ß), and complement C3 (c3). Gene ontology enrichment highlighted distinct immune activation patterns between fed and unfed groups, with enhanced pathogen recognition and pro-inflammatory responses in unfed fish. These findings suggest feeding prior to infection may exacerbate disease pathology, potentially by creating a physiological state conducive to facilitate pathogen proliferation and dampened early immune responses, whereas short-term fasting appears to promote early immune activation. This study provides novel insights into the complex interplay between feed status, physical injury, and immune response to vAh infection.