Immune Activation Following Vaccination of Streptococcus iniae Bacterin in Asian Seabass (Lates calcarifer, Bloch 1790)

Pornpawit Tanpichai; Surachart Chaweepack; Saengchan Senapin; Patharapol Piamsomboon; Janenuj Wongtavatchai

doi:10.3390/vaccines11020351

Immune Activation Following Vaccination of Streptococcus iniae Bacterin in Asian Seabass (Lates calcarifer, Bloch 1790)

Vaccines (Basel). 2023 Feb 3;11(2):351. doi: 10.3390/vaccines11020351.

Authors

Pornpawit Tanpichai¹, Surachart Chaweepack², Saengchan Senapin^{3

4}, Patharapol Piamsomboon¹, Janenuj Wongtavatchai¹

Affiliations

¹ Department of Veterinary Medicine, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand.
² Chanthaburi Coastal Aquaculture Research and Development Center, Chanthaburi 22000, Thailand.
³ Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
⁴ National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand.

Abstract

Juvenile Asian seabass (Lates calcarifer) (body weight 10 ± 0.7 g) were intraperitoneally injected with 10¹² CFU fish^-1 of formalin-killed Streptococcus iniae. The protective efficacy of the vaccine on survival and infection rate was assessed upon challenge at 4, 8, 12, 20, and 28 weeks post-vaccination. The results revealed that the challenged vaccinated fish showed no mortality at all time points, and the control fish presented 10-43.33% mortality. The infection rate at 2 weeks post-challenge was 0-13.33% in the vaccinated fish and 30-82.35% in the control group. At 8 weeks post-vaccination, the vaccinated fish showed comparable ELISA antibody levels with the control; however, the antibody levels of the vaccinated fish increased significantly after the challenge (p < 0.05), suggesting the presence of an adaptive response. Innate immune genes, including MHC I, MHC II, IL-1β, IL-4/13B, and IL-10, were significantly upregulated at 12 h post-challenge in the vaccinated fish but not in the control. In summary, vaccination with S. iniae bacterin provided substantial protection by stimulating the innate and specific immune responses of Asian seabass against S. iniae infection.

Keywords: Asian seabass; ELISA; aquaculture; bacterin; formalin-killed vaccine; qPCR; streptococcosis.

Grants and funding

This study was funded by the 100th Anniversary Chulalongkorn University Fund for Doctoral Scholarship and the 90th Anniversary of Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund) Chulalongkorn University, Bangkok, Thailand.