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Title: Humoral immune response of catfish immunized with extracellular products of Aeromonas hydrophila

item Zhang, Dunhua
item Xu, Dehai
item Shoemaker, Craig

Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2014
Publication Date: 2/20/2015
Citation: Zhang, D., Xu, D., Shoemaker, C.A. 2015. Humoral immune response of catfish immunized with extracellular products of Aeromonas hydrophila [abstract]. Aquaculture America 2015. p. 514.

Interpretive Summary:

Technical Abstract: Aeromonas hydrophila is emerging as one of the major concerns in catfish aquaculture in the Southeastern United States due to recent outbreaks of motile aeromonad septicemia (MAS) caused by the pathogen. Prophylactic treatment is being sought to prevent MAS. Since multiple virulence associated factors were identified in extracellular products (ECP) of A. hydrophila, use of ECP, prepared from a virulent A. hydrophila in liquid culture, as immunogens was investigated. Catfish fingerlings (average weight of 11 g) were individually immunized with 0.8 µg of ECP protein in 100 µl of PBS-Freund’s adjuvant (50:50) emulsion by intraperitoneal injection. Two weeks post immunization, serum collected from fish immunized developed strong humoral immune response. The anti-ECP serum could aggregate cells of homogenous bacteria as well as other virulent isolates of A. hydrophila. The agglutination titers increased from two to four weeks post immunization and sustained a high level at week seven. Vaccinated fish were immune protected from infection by the pathogen with 100% of RPS (relative percent survival). The anti-ECP serum could also provide naïve fish with immediate protection against A. hydrophila as evidenced by passive immunization. Immunoblotting analysis showed that the anti-ECP serum contained antibodies that bound to specific targets in the ECP, including proteins and lipopolysaccharide-like molecules. These antibody-recognized targets may serve as important immunogens. Development of recombinant protein vaccines for prophylaxis of MAS would therefore merits further investigations.