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ARS Home » Southeast Area » Auburn, Alabama » Aquatic Animal Health Research » Research » Research Project #432601

Research Project: Evaluation of a Trivalent Vaccine for Simultaneous Protection Against Columnaris, Enteric Septicemia, and Aeromonas Hydrophilia

Location: Aquatic Animal Health Research

Project Number: 6010-32000-026-09-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jul 3, 2017
End Date: Jul 2, 2020

Objective:
Aquaculture is the fastest growing sector of animal agriculture. However, sustainable expansion and intensification of aquaculture worldwide has been severely hampered by disease. In the U.S. catfish industry, the largest segment of U.S. aquaculture, disease-based mortality levels can reach nearly 60% over the course of a production cycle. While an array of bacterial diseases pose problems to farmed catfish, three of the most important are caused by gram negative bacteria. Collectively, these are motile Aeromonas septicemia caused by Aeromonas hydrophila, enteric septicemia of catfish caused by Edwardsiella ictaluri, and columnaris disease caused by the opportunistic bacterial pathogen Flavobacterium columnare. Over the last year in Alabama alone, these diseases were responsible for the loss of over 6 million pounds of fish. Despite the importance of these diseases, non-antibiotic strategies for their prevention or control are scarce to nonexistent. New approaches are desperately needed to mitigate or combat disease outbreaks on farms, particularly as public concern is mounting over antibiotic use in both terrestrial and aquatic livestock. Accordingly, vaccine-based approaches represent the most practical and feasible platforms for controlling bacterial diseases on farms. Indeed, vaccines are not new to the catfish industry where prior vaccination strategies revealed poor results. Previously, vaccines used in industry settings targeted only a single pathogen which failed to protect against other serious diseases. Moreover, vaccine delivery was accomplished through waterborne (immersion) vaccination of newly hatched catfish, which did not confer long lasting immune protection throughout a production cycle (12-18 months). In the studies proposed here, our research team will improve upon these first generation approaches by exploring the efficacy and feasibility of a trivalent vaccine developed from the three most problematic pathogens of farmed catfish (see above). The bacterial isolates used to make this vaccine will be pathogenic isolates endemic to the West Alabama farming region (i.e, “autogenous”) and will be administered as inactivated (killed) bacterins (along with an adjuvant) to fingerling catfish by intraperitoneal injection.

Approach:
Working closely with the research team of the Auburn University School of Fisheries, Aquaculture, and Aquatic Sciences (SFAAS) we will examine whether a trivalent vaccine—prepared from killed bacterial isolates obtained from infected fish in the west Alabama farming region—can confer protection when administered to fingerling channel and hybrid catfish by intraperitoneal injection. Auburn University has developed the crucial infrastructure for conducting this applied field study. More specifically, Auburn University is utilizing in-pond raceway systems (IPRS) to translate research findings to the field in west Alabama. These are fully contained systems that operate within actual catfish production ponds. These systems allow for the natural development of disease outbreaks and allow for a high level of experimental replication in industry settings. Currently, IPRS units installed in three ponds, each containing 4 IPRS units per pond with 4 cells per IPRS. Approximately 4-5 weeks after vaccination fish will be stocked into cells with approximately 1,300 fish each. Fish will be monitored daily and the study will be conducted throughout the 2017 growing season. Fish performance will be compared to unvaccinated controls with an emphasis on survival, growth, and feed conversion.