Immune responses and protection of fry Nile tilapia (Oreochromis niloticus) immunized by immersion and oral bivalent vaccines against streptococcus agalactiae and aeromonas veronii | |
| Author | Quentin, Andres Ludovic Stephane |
| Call Number | AIT Thesis no.AQ-22-05 |
| Subject(s) | Fishes--Diseases Fishes--Vaccination Fishes--Immunology Tilapia |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Aquaculture and Aquatic Resources Management |
| Publisher | Asian Institute of Technology |
| Abstract | Fighting bacterial infections inducing mass mortality in fish is critically important in the aquaculture industry in order to sustain its intensification. This research project aims to develop simple and inexpensive heat-killed inactivated bivalent vaccines against group B streptococci (GBS) Streptococcus agalactiae and against gram-negative Aeromonas veronii for prophylaxis of Nile tilapia (Oreochromis niloticus) for which there is cur rently no vaccine commercially available in Thailand. The objective of the study is to characterize a part of the immune response elicited in Nile tilapia after vaccination. A total of (n = 900 fry) with an average mass of (1.1g +− 0.1g) were divided into 3 groups in separate tanks and vaccinated: Control (Ct) (untreated condition, no im munization is expected); IMM+OR: Immersion vaccine in 20L for 4.5h, containing 10 million CFU/mL per bacteria as inactivated culture broth (day 1) + oral booster vaccine fed twice daily (in amount of 3% fish bodyweight) containing 10 billion inactivated CFU/kg of S.agalactiae and 1 billion inactivated CFU/kg of A.veronii and coated with 100mL of soybean oil per kg of feed (day 21 to day 28). OR+OR: first oral vaccina tion (day 1 to day 7) with oral booster (day 21 to day 28). Specific immune responses to vaccinations in each group (Ct, IMM+OR, OR+OR) was determined by indirect ELISA assay. As a final step, the fish were transfered into 6 tanks of 100L. Bacterial challenge trials were conducted by immersing duplicates of 50 fish per tank filled with a diluted solution harboring live bacteria (either S.agalactiae or A.veronii) at 10 million CFU/mL in 19L for 6h, then diluted by adding 19L of extra clean water, and monitored for two weeks. From the results of Elisa assay, it was observed that both IMM+OR and OR+OR could stimulate IgM production against the two pathogens. OR+OR failed to protect (0% of overall survival probability and 51% against A.veronii and S.agalactiae) and only IMM+OR was found to be trustworthy and effective in eliciting protection and preventing mortalities after artificial infection trials (more than 80% of overall survival probability against both pathogens). This research propose a new effective vaccination approach that is both convenient and inexpensive against S.agalactiae and A.veronii in the Nile tilapia fry and which could ultimately benefit the small and medium scale fish farms and nurseries. |
| Year | 2022 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Ha, Thanh Dong;Salin, Krishna R. (Co-Chairperson) |
| Examination Committee(s) | Loc, Thai Nguyen;Lumpan Poolsawat; |
| Scholarship Donor(s) | AIT Scholarships; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2022 |