Montanide™ ISA 763A VG and ISA 761 VG induce different immune pathway responses in rainbow trout (Oncorhynchus mykiss) when used as adjuvant for an Aeromonas salmonicida bacterin

Kimberly A. Veenstra, Tiehui Wang, K. Spencer Russell, Lincoln Tubbs, Juliette Ben Arous, Christopher J. Secombes

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Adjuvants are the helper substances that increase vaccine efficacy by enhancing the potency and longevity of specific immune responses to antigens. Most existing fish vaccines are presented in the form of oil-based emulsions delivered by intraperitoneal injection. The characterization of their mode of action is a valuable aid to future vaccine development, particularly for the potential identification and stimulation of specific immunological pathways related to the desired protective response. This study characterized the expression of selected immune-related genes in the peritoneal cavity, head kidney and spleen following the administration of two adjuvanted-bacterial vaccines thought to induce humoral (Montanide™ ISA 763A VG) or humoral and cell mediated (Montanide™ ISA 761 VG) immune responses, to determine if differences in responsiveness are readily apparent. The most informative site was the spleen, where Montanide™ ISA 763A VG + bacterin gave rise to upregulation of genes driving T-cell/lymphoid responses, namely IL-2, IL-15 and IL-21. This combined with upregulation of IFNγ1 and IFNγ2, IL-4/13B2, p35A1 and p40 (B1 and C) indicated that the induction of Th1 and possibly Th2 immunity was occurring in fish vaccinated with this adjuvant. Perhaps the most intriguing finding was the lack of a detectable Th1 response in fish given Montanide™ ISA 761 VG + bacterin, suggesting some other arm of the immune system is activated to give protection. Whatever the reason for the different responses detected, it is clear from the present study that the adjuvant used has a major impact on the responses elicited. Since these differences are readily detectable it allows, in principle, their use to help select the most appropriate adjuvants for inclusion into fish vaccines, where the type of response elicited may need to be tailored to a particular pathogen to confer protection.
Original languageEnglish
Pages (from-to)171-183
Number of pages13
JournalFish & Shellfish Immunology
Early online date30 Apr 2021
Publication statusPublished - 1 Jul 2021

Bibliographical note

KAV was supported by Elanco and Seppic to undertake a PhD program at the University of Aberdeen. TW received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS is funded by the Scottish Funding Council (grant reference HR09011).


  • Vaccine
  • Water in oil (w/o) adjuvant
  • Montanide™
  • Rainbow trout
  • Gene expression
  • Peritoneal cells
  • Head kidney
  • Spleen


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