Abstract
Streptococcus agalactiae is one of the most important pathogens infecting tilapia worldwide and causes meningoencephalitis, septicemia and high mortalities with considerable losses. Various types of vaccines have been developed against S. agalactiae infection, such as inactivated vaccines, live attenuated vaccines and subunit vaccines. Bacterial ghosts (BGs) are nonliving, empty cell envelopes and have been reported as novel vaccine candidates. Therefore, the main aims of this study were to develop an S. agalactiae ghost vaccine (SAGV) and to evaluate the immune response and protective effect of SAGV against S. agalactiae with two novel adjuvants, Montanide™ ISA 763B VG and Montanide™ GEL02. Nile tilapia, mean weight 50 g, were divided into four groups as follows; 1) fish injected with PBS as control, 2) fish injected with the SAGV alone; 3) fish injected with the SAGV+Montanide™ ISA 763B VG; and 4) fish injected with SAGV+Montanide™ GEL02. Following vaccination, innate immunity parameters including serum lysozyme, myeloperoxidase, catalase, and bactericidal activity were all significantly enhanced. Moreover, specific serum IgM antibodies were induced and reached their highest level 2–8 weeks post vaccination. Importantly, the relative percent survival of tilapia vaccinated against the SAGV formulated with both adjuvants was 80–93%. Furthermore, the transcription of immune-related genes (IgM, TCRβ, IL-1β, IL-8 and TNFα) were up-regulated in tilapia after vaccination, indicating that both cellular and humoral immune responses were induced by these adjuvanted vaccines. In summary, Montanide™ ISA 763B VG and Montanide™ GEL02 can enhance immunoprotection induced by the SAGV vaccine against streptococcosis, demonstrating that both have value as potential adjuvants of fish vaccines.
Original language | English |
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Pages (from-to) | 19-29 |
Number of pages | 11 |
Journal | Fish & Shellfish Immunology |
Volume | 116 |
Early online date | 19 Jun 2021 |
DOIs | |
Publication status | Published - 30 Sept 2021 |
Bibliographical note
AcknowledgementsThis research was financially supported by the Office of the Permanent Secretary (OPS) and National Research Council of Thailand (NRCT), through the MRG Grant for the Development of New Lecturer (grant no. RGNS63-149) awarded to E.W. This Project was partially supported By Mahasarakham University. B.W. was supported by the National Natural Science Foundation of China (Grant No. 31702386), and International Cooperation Science & Technology Planning Project of Guangdong Province of China (Grant No. 2017A050501037).
Keywords
- Immune response
- New adjuvants
- Montanide™ ISA 763B VG
- Montanide™ GEL02
- Ghost vaccine
- Nile tilapia