Streptococcus disease in fish is Gram-positive bacterial infection that can cause serious illness and death. Vaccination strategies for fish include injection, immersion, and oral administration.
Streptococcosis is a zoonotic disease with the potential to affect humans. Vaccines adjuvanted with saponins have been approved against Streptococcus equi and saponin adjuvants have shown correlates of protection in mice against Streptococcus group A [1], group B [2], S. suis [3], Streptococcus equi in horses [4].
In vaccinated fish, saponin adjuvants can effectively enhance both mucosal and systemic immune responses. Two immersion vaccines adjuvanted with saponin and a polymer have been approved for use in Salmonidae. In a comparative study, turbot fish that received bacterin immersion vaccination with saponin exhibited a significantly higher relative percent survival than the positive control group vaccinated against Vibrio anguillarum via intraperitoneal injection (Figure 1) [5].
Oral immunization of Olive Flounder with a saponin-adjuvanted formulation resulted in no observed adverse clinical effects and demonstrated positive digestibility [6].
References
1. Rivera-Hernandez, T. et al., 2020. Vaccine-Induced Th1-Type Response Protects against Invasive Group A Streptococcus Infection in the Absence of Opsonizing Antibodies. mBio, 11(2).
2. Soto, J. A. et al., 2019. Cellular immune response induced by surface immunogenic protein with AbISCO-100 adjuvant vaccination decreases group B Streptococcus vaginal colonization. Molecular Immunology, Volume 111, pp. 198-204.
3. Gonzaga, Z. J. C. et al., 2021. Engineering Antigens to Assemble into Polymer Particle Vaccines for Prevention of Streptococcus suis Infection. Vaccines, 9(12), p. 1386.
4. Waller, A. et al., 2007. Vaccination of horses against strangles using recombinant antigens from Streptococcus equi. Vaccine, 25(18), pp. 3629-3635.
5. Wang, Y., Wang, X., Huang, J. & Li, J., 2016. Adjuvant Effect of Quillaja saponaria Saponin (QSS) on Protective Efficacy and IgM Generation in Turbot (Scophthalmus maximus) upon Immersion Vaccination. International Journal of Molecular Sciences, 17(3), p. 325.
6. Jung, M.-H., Kole, S. & Jung, S.-J., 2022. Efficacy of saponin-based inactivated rock bream iridovirus (RBIV) vaccine in rock bream (Oplegnathus fasciatus). Fish & Shellfish Immunology, Volume 121, pp. 12-22.
