First Investigation of the Optimal Timing of Vaccination of Nile Tilapia (Oreochromis niloticus) Larvae against Streptococcus agalactiae

Benchawan Kumwan; Anurak Bunnoy; Satid Chatchaiphan; Pattanapon Kayansamruaj; Ha Thanh Dong; Saengchan Senapin; Prapansak Srisapoome

doi:10.3390/vaccines11121753

First Investigation of the Optimal Timing of Vaccination of Nile Tilapia (Oreochromis niloticus) Larvae against Streptococcus agalactiae

Vaccines (Basel). 2023 Nov 24;11(12):1753. doi: 10.3390/vaccines11121753.

Authors

Benchawan Kumwan^{1

2}, Anurak Bunnoy^{1

2}, Satid Chatchaiphan³, Pattanapon Kayansamruaj^{1

2}, Ha Thanh Dong⁴, Saengchan Senapin^{5

6}, Prapansak Srisapoome^{1

2}

Affiliations

¹ Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, 50 Paholayothin Road, Ladyao, Chatuchak, Bangkok 10900, Thailand.
² Center of Excellence in Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, 50 Paholayothin Road, Ladyao, Chatuchak, Bangkok 10900, Thailand.
³ Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand.
⁴ Aquaculture and Aquatic Resources Management, Department of Food Agriculture and Bioresources, School of Environment, Resources and Development, Asian Institute of Technology, Pathum Thani 12120, Thailand.
⁵ National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand.
⁶ Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok 10400, Thailand.

Abstract

To investigate early immune responses and explore the optimal vaccination periods, Nile tilapia at 1, 7, 14, 21, 28, 35, and 42 days after yolk sac collapse (DAYC) were immersed in formalin-killed Streptococcus agalactiae vaccine (FKV-SA). A specific IgM was first detected via ELISA in the 21 DAYC larvae (0.108 g) at 336 h after vaccination (hav), whereas in the 28-42 DAYC larvae (0.330-0.580 g), the specific IgM could be initially detected at 24 hav. qRT-PCR analysis of the TCRβ, CD4, MHCIIα, IgHM, IgHT, and IgHD genes in 21-42 DAYC larvae immunized with the FKV-SA immersion route for 24, 168, and 336 hav revealed that the levels of most immune-related genes were significantly higher in the vaccinated larvae at all DAYCs than in the control larvae (p < 0.05) at 336 hav. Immunohistochemistry demonstrated stronger IgM signals in the gills, head kidney, and intestine tissues at 21, 28, and 35 DAYC in all vaccinated larvae compared with the control. Interestingly, at all DAYCs, FKV-SA larvae exhibited significantly higher survival rates and an increased relative percent survival (RPS) than the control after challenge with viable S. agalactiae, particularly in larvae that were immunized with FKV-SA at 168 and 336 hav (p < 0.05).

Keywords: Nile tilapia; Oreochromis niloticus; Streptococcus agalactiae; formalin-killed vaccine; immunocompetence.

Grants and funding

P-21-51690/National Science and Technology Development Agency