Efficacy of monovalent and bivalent vaccine against streptococcus iniae and flavobacterium covae in Asian Seabass (Lates calcarifer)

Name: Pimchanok Tumree

LCSH: Kasetsart University -- Theses. M.S. (Fishery Science and Technology) 2023.

Classification :.LCCS: SH167.S33

LCSH: Kasetsart University. -- Faculty of Fisheries -- Theses.

LCSH: Sea basses.

LCSH: Vaccines.

Abstract: Streptococcosis and columnaris caused by Streptococcus spp. and Flavobacterium spp. have been recognized as critical problems in Asian seabass aquaculture development because they cause severe mortality. In this study, we identified various isolates of S. iniae and F. covae from diseased Asian seabass farmed in Thailand for use as candidates for vaccine development. The efficacy of the vaccines was evaluated by challenge tests and immune parameter analyses in fish that received whole-cell-based monovalent and bivalent vaccines containing S. iniae (Sin) and F. covae (Fco) delivered by top-dressed feed (TD) and intraperitoneal injection (IP). The results showed that all vaccinated groups exhibited increased antibody titers compared with control fish that peaked on day 28 after booster administration with high detection levels in the Sin-IP and Fco-IP groups. Moreover, the immune responses to the injected monovalent vaccines (SinIP and Fco-IP) were better than the responses in the other vaccinated groups. The hematological and innate immunological parameters were significantly increased by Sin-IP and Fco-IP, particularly lysozyme activity, nitroblue tetrazolium (NBT) activity, bactericidal activity, and white blood cell numbers, and immune-related genes, including IgM, MHC-IIα, TCRß and CD4, were significantly upregulated in the head kidney, whole blood and spleen (P < 0.05). After experimental challenge, survival in the Sin-IP and Fco-IP groups was significantly higher than that in the Sin-TD, Fco-TD, Sin+Fco-TD, and Sin+Fco-IP groups, with 80.0% and 60.0% survival after S. iniae and F. covae infection, respectively. In contrast, survival after bacterial challenge in the control groups was 10% in each group. Histopathological analysis revealed that Sin-IP- and Fco-IP-vaccinated fish exhibited significantly more goblet cells in the intestines and melanomacrophage centers (MMCs) in the head kidney and spleen than those in the other groups (P < 0.05). Overall, the results of our study indicated that the monovalent vaccines Sin-IP and Fco-IP provoked better vaccine efficacy and immune responses than their orally administered counterparts, and these results are consistent with those from the immunological assays that showed significantly increased responses after immunization.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Prapansak Srisapoome

Role: Thesis Advisor

Name: Tang Xiaoqian

Role: Thesis Co-Advisor

Created: 2023

Modified: 2025-06-25

Issued: 2025-06-25

วิทยานิพนธ์/Thesis

วิทยานิพนธ์/Thesis

application/pdf

URL: http://www.lib.ku.ac.th/KUthesis/2566/pimchanok-tum-all.pdf

CallNumber: SH167.S33.P55

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Fishery Science and Technology

Grantor: Kasetsart University

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