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ARS Home » Southeast Area » Auburn, Alabama » Aquatic Animal Health Research » Research » Publications at this Location » Publication #420356

Research Project: Integrated Research to Improve Aquatic Animal Health in Warmwater Aquaculture

Location: Aquatic Animal Health Research

Title: Efficacy of an immersion-based formalin-killed vaccine in largemouth bass Micropterus salmoides against motile Aeromonas septicemia.

Author
item SCHNEIDER, CHANDLER - Auburn University
item LEDFORD, OWEN - Auburn University
item Lafrentz, Benjamin
item Garcia, Julio
item BUTTS, IAN - Auburn University
item BRUCE, TIMOTHY - Auburn University

Submitted to: Aquaculture
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2024
Publication Date: 3/6/2025
Citation: Schneider, C.M., Ledford, O.P., Lafrentz, B.R., Garcia, J.C., Butts, I.A., Bruce, T.J. 2024. Efficacy of an immersion-based formalin-killed vaccine in largemouth bass Micropterus salmoides against motile Aeromonas septicemia [ABSTRACT]. Aquaculture 2025, New Orleans, Louisiana. March 6-10, 2025.

Interpretive Summary: Aquaculture expansion in the United States has brought novel challenges as producers look to magnify and diversify their operations. Recent data has indicated increased largemouth bass (LMB; Micropterus salmoides) production as culturists aim to capitalize on the high market value. While this lucrative opportunity has provoked much interest, production facilities must navigate LMB through their critical early-life stages. As one of the leading causes of mortality in warmwater culture, motile Aeromonas septicemia (MAS; including Aeromonas hydrophila and Aeromonas veronii) poses a significant threat to production facilities. Providing culturists with practical alternative tools to combat disease, such as autogenous vaccines, can be valuable for reducing mortality. To determine the optimal timeframe for vaccinating LMB fingerlings, three experimental vaccination periods of 0-, 2- and 4-months will be studied (time 0 < 5g). At each timepoint, formalin-killed cultures of A. veronii (ARS-LMB-32-2018) and A. hydrophila (ARS-LMB-9-2022) will be administered via a thirty-minute static immersion bath. The LMB will be monitored for thirty days post-vaccination (dpv) to allow the specific immune response to be generated. The spleen, kidney, and distal intestines will be sampled at 0-, 15-, and 30 days post-inoculation (dpi) for targeted gene expression to assess vaccine-induced immune responses. The microbial gut communities will also be characterized. At these times, sera will be collected to evaluate Aeromonas spp.-specific antibody titers via ELISA. Additionally, morphometric analyses will be conducted to observe notable changes in response to vaccination. At thirty dpv, LMB will be challenged using a standardized fin-clip methodology and subjected to a one-hour static bath at ~2 x 107 CFU mL-1. Cumulative percent mortality will be monitored incrementally through the 7-day challenge duration. With this long-term study, we aim to improve the understanding of LMB fingerling response to formalin-killed immersion bath vaccinations of A. veronii & A. hydrophila and the potential for mortality reduction. Studies such as these will provide vital information to producers to reduce mortality, avoid antibiotic usage, and increase product security as the culture of the species expands.

Technical Abstract: Aquaculture expansion in the United States has brought novel challenges as producers look to magnify and diversify their operations. Recent data has indicated increased largemouth bass (LMB; Micropterus salmoides) production as culturists aim to capitalize on the high market value. While this lucrative opportunity has provoked much interest, production facilities must navigate LMB through their critical early-life stages. As one of the leading causes of mortality in warmwater culture, motile Aeromonas septicemia (MAS; including Aeromonas hydrophila and Aeromonas veronii) poses a significant threat to production facilities. Providing culturists with practical alternative tools to combat disease, such as autogenous vaccines, can be valuable for reducing mortality. To determine the optimal timeframe for vaccinating LMB fingerlings, three experimental vaccination periods of 0-, 2- and 4-months will be studied (time 0 < 5g). At each timepoint, formalin-killed cultures of A. veronii (ARS-LMB-32-2018) and A. hydrophila (ARS-LMB-9-2022) will be administered via a thirty-minute static immersion bath. The LMB will be monitored for thirty days post-vaccination (dpv) to allow the specific immune response to be generated. The spleen, kidney, and distal intestines will be sampled at 0-, 15-, and 30 days post-inoculation (dpi) for targeted gene expression to assess vaccine-induced immune responses. The microbial gut communities will also be characterized. At these times, sera will be collected to evaluate Aeromonas spp.-specific antibody titers via ELISA. Additionally, morphometric analyses will be conducted to observe notable changes in response to vaccination. At thirty dpv, LMB will be challenged using a standardized fin-clip methodology and subjected to a one-hour static bath at ~2 x 107 CFU mL-1. Cumulative percent mortality will be monitored incrementally through the 7-day challenge duration. With this long-term study, we aim to improve the understanding of LMB fingerling response to formalin-killed immersion bath vaccinations of A. veronii & A. hydrophila and the potential for mortality reduction. Studies such as these will provide vital information to producers to reduce mortality, avoid antibiotic usage, and increase product security as the culture of the species expands.