Comparative efficacy and immune responses induced by aluminium hydroxide gel (Algel) adjuvanted and non-adjuvanted formalin killed Vibrio alginolyticus vaccines in Asian seabass Lates calcarifer (Bloch, 1790)

Azhar Shahansha, T S and Pradeep, M A and Ramesh Kumar, P and Suresh Babu, P P and Joshy, C G and Dhanutha, N R and Kottayi, Nidhiya and Nivya, A and Sanil, N K (2026) Comparative efficacy and immune responses induced by aluminium hydroxide gel (Algel) adjuvanted and non-adjuvanted formalin killed Vibrio alginolyticus vaccines in Asian seabass Lates calcarifer (Bloch, 1790). Indian Journal of Fisheries, 73 (3). pp. 100-110. ISSN 0970-6011

Text Indian Journal of Fisheries_2026_Pradeep M A.pdf Download (1MB)

Abstract

Vibriosis caused by Vibrio alginolyticus is an important bacterial disease affecting Asian seabass Lates calcarifer (Bloch, 1790). This study evaluated the protective efficacy and immune responses induced by two intraperitoneally administered formalin killed V. alginolyticus vaccine formulations: a non-adjuvanted bacterin (T1) and an aluminium hydroxide gel (Algel) adjuvanted bacterin (T2). Phosphate buffered saline (PBS) injected fish served as the challenged control (T0), while a non-challenged naive group (T3) was maintained to monitor background mortality. Each vaccine was administered at a dose of 0.2 ml containing 1×108 CFU-equivalent per fish. Protection was assessed three weeks after vaccination following intraperitoneal challenge with live V. alginolyticus at 1×108 CFU per fish. Serum agglutination titre, serum bactericidal activity, serum lysozyme activity, and the expression of complement factor H (CFH), Cystatin B, HSP70, and HSP90α in the spleen and head kidney were evaluated at 7, 14 and 21 days post-vaccination (DPV). T2 showed the highest survival (90%) and relative percent survival (RPS; 86.4%), followed by T1 (80% survival; 72.7% RPS), whereas the T0 challenged control showed 26.6% survival and no mortality was observed in the nonchallenged naive group (T3). T2 produced higher serum agglutination titres and lysozyme activity, particularly at 14 DPV. At 21 DPV, bacterial survival percentage was similar between T1 (77.2%) and T2 (77.9%; p>0.05), but both were lower than the T0 control (92.1%). Immune gene expression showed tissue- and time-dependent patterns without a uniform response across the four genes. Overall, both formalin killed vaccine formulations provided substantial protection under experimental challenge conditions, with the Algel adjuvanted formulation demonstrating enhanced survival, RPS, and early humoral and innate immune responses. The practical advantages of Algel over the non-adjuvanted formulation requires further evaluation through analysis of cost-effectiveness, assessment of duration of protective immmunity, booster vaccination studies and field studies.

Actions (login required)

View Item