Immune effect of Aeromonas veronii vaccines prepared with a low pathogenic strain FS12001 to Carassius auratus gibelio

Aeromonas veronii can infect a variety of aquatic and terrestrial animals and cause motile aeromonad septicemia (MAS).To explore the immune effect of the vaccine prepared with A. veronii low pathogenic strain FS12001, Carassius auratus gibelio were immunized with live vaccine, inactivated vaccine, ISA763A-inactivated vaccine and propolis-inactivated vaccine prepared with FS12001 through intraperitoneal injection, with ISA763A- 0.65% NaCl, propolis- 0.65% NaCl and 0.65% NaCl used as controls. The gene expressions of IgM, IL-1β and LZM were detected by real-time quantitative PCR (qRT-PCR) in spleen tissues at 1, 3, 5, 7 and 14 d post immunization (dpi). Sera were collected from the tail vein at 7, 14, 21, 28, 42 and 48 dpi. The specific antibody IgM levels were detected through indirect ELISA. SOD activity and LZM activity were measured. The experimental groups were challenged with two A.veronii virulent strains at 28 dpi, and the relative percent survival (RPS) was calculated. The gene expressions of IgM, IL-1β and LZM in spleen tissues of each immunized group were higher than those of the 0.65% NaCl control, and the expressions of ISA763A-inactivated vaccine group and propolis-inactivated vaccine group were significantly higher than those of all other groups. The serum-specific antibody levels of each vaccine-immunized group were significantly higher than those of the 0.65% NaCl and adjuvant controls. LZM activity values were highest at 28 dpi in all vaccine-immunized groups, and SOD activity values were the highest at 7 dpi in the inactivated vaccine group, ISA763A-inactivated vaccine group and propolis-inactivated vaccine group. The RPSs of live vaccine group, inactivated vaccine group, ISA763A-inactivated vaccine group and propolis-inactivated vaccine group challenged with AVCA07 were 63%, 56%, 100% and 56%, respectively, and the RPSs of these immune groups challenged with YC170511 were 59%, 55%, 93% and 72%, respectively. This study shows that the several vaccines prepared with A.veronii FS12001 can increase the gene expressions of IgM, IL-1β and LZM, serum specific antibody level, SOD activity and LZM activity, and enhance the ability of C. auratus gibelio to resist A.veronii infection. This study can provide the basis for A.veronii vaccines and prevention and control of MAS.