Field Efficacy of a Feed-Based Inactivated Vaccine against Vibriosis in Cage-Cultured Asian Seabass, Lates calcarifer, in Malaysia

Abstract

Vibrio spp. are important aquaculture pathogens that cause vibriosis, affecting large numbers of marine fish species. This study determines the field efficacy of a feed-based inactivated vaccine against vibriosis in cage-cultured Asian seabass. A total of 4800 Asian seabass, kept in a field environment, were separated equally into two groups (vaccinated and non-vaccinated) in duplicate. Fish of Group 1 were orally administered the feed-based vaccine on weeks 0 (prime vaccination), 2 (booster), and 6 (second booster) at 4% body weight, while the non-vaccinated fish of Group 2 were fed with a commercial formulated pellet without the vaccine. Fish gut, mucus, and serum were collected, the length and weight of the fish were noted, while the mortality was recorded at 2-week intervals for a period of 16 weeks. The non-specific lysozyme activities were significantly (p < 0.05) higher in the fish of Group 1 than the non-vaccinated fish of Group 2. Similarly, the specific IgM antibody levels in serum and mucus were significantly (p < 0.05) higher in Group 1 than in Group 2, as seen in the second week, with the highest level 8 weeks after primary immunization. At week 16, the growth performance was significantly (p < 0.05) better in Group 1 and showed lower bacterial isolation in the gut than Group 2. Despite the statistical insignificance (p > 0.05), the survival rate was slightly higher in Group 1 (71.3%) than Group 2 (67.7%). This study revealed that feed-based vaccination improves growth performance, stimulates innate and adaptive immune responses, and increases protection of cultured Asian seabass, L. calcarifer, against vibriosis.

Review of current perspectives and future outlook on bacterial disease prevention through vaccination in Asian seabass (Lates calcarifer)

“…In a field experiment by Amir‐Danial et al. (2022), a feed‐based inactivated vaccine exhibited enhanced immune responses, improved growth, and heightened protection against vibriosis in cage‐cultured Asian seabass with a survival rate of 71.3%. A study by Raju et al.…”

Evaluating the Intestinal Immunity of Asian Seabass (Lates calcarifer, Bloch 1790) following Field Vaccination Using a Feed-Based Oral Vaccine

“…Previously, we developed and tested a feed-based vaccine against vibriosis that was proven to be efficacious to prevent vibriosis in Asian sea bass and grouper in field settings [ 16 , 17 ]. Furthermore, it also resulted in significant increment of growth rate, decreased rate of Vibrio spp.…”

“…Furthermore, it also resulted in significant increment of growth rate, decreased rate of Vibrio spp. isolation, and higher lysozyme activities and IgM in the mucus and serum [ 16 ]. Since this is a feed-based vaccine, it is expected to also stimulate the mucosal gut immunity.…”