Alternatives to mineral oil adjuvants in vaccines against Aeromonas salmonicida subsp. salmonicida in rainbow trout offer reductions in adverse effects

Abstract

In an effort to reduce the frequency and severity of adverse reactions seen from the use of mineral oil adjuvants in salmonid fish, the effects of two alternative adjuvants were assessed, focusing on the induction of adverse effects as well as protection. Using rainbow trout (Oncorhynchus mykiss) as recipients, injection vaccines based on formalin-inactivated Aeromonas salmonicida subspecies salmonicida were formulated with CpG oligodeoxynucleotides, the liposomal cationic adjuvant formulation 01 (CAF01) or with Freund’s incomplete adjuvant and administered intraperitoneally. Control groups of unvaccinated, Tris-buffered saline-injected or bacterin-injected individuals were included, and each group included in the study held a total number of 240 individuals. Subsequently, individuals from each group were examined for differences in Fulton’s condition factor, macro- and microscopic pathological changes, as well as protection against experimental infection with A. salmonicida. While adverse effects were not eliminated, reductions in microscopic and macroscopic adverse effects, in particular, were seen for both the nucleotide- and liposome-based vaccine formulations. Furthermore, the induced protection appears similar to that of the benchmark formulation, thus introducing viable, potential alternative types of adjuvants for use in future fish vaccines.

Aggregating behaviour in invasive Caribbean lionfish is driven by habitat complexity

“…Fat weight was obtained by removing all fat deposits from within the gut cavity and weighing these using an electronic balance. Fulton’s condition factor, which was also used as a measure of feeding success, was calculated as body weight divided by total length cubed 65,66 , with higher values indicating that fish were heavier for their size. Macroscopic analysis of the gonads was used to determine sex 67 .…”

Injection Vaccines Formulated with Nucleotide, Liposomal or Mineral Oil Adjuvants Induce Distinct Differences in Immunogenicity in Rainbow Trout

“…Disclaimer: The work presented in this research article is part of a larger study, parts of which have previously been published [20]. Since the present study builds upon the same experimental setup, experimental animals, vaccine formulations, immunizations, and sampling program, those details have already been described and published in the abovementioned publication.…”

“…Meanwhile, an experimental infection revealed no differences in the induced protection between the three vaccine formulations. As our earlier work thus demonstrated induced protection as well as varying safety profiles conferred by three, theoretically distinctive experimental vaccines, as well as by the injection of bacterin alone [20], further investigation of the underlying immune responses for each vaccine formulation was warranted.…”

“…We have previously investigated the protective and adverse effects induced by formulating a whole-cell bacterin of inactivated A. salmonicida with either CpG oligodeoxynucleotides (CpG ODNs) or the cationic adjuvant formulation 01 (CAF01) liposomal adjuvant compared to a benchmark formulation of the same bacterin with Freund's incomplete adjuvant (FIA) [20]. The choice of adjuvants was based on expected safety profiles, as well as the suspected differential induction of immune responses.…”

Effect of Bivalent Vaccines against Vibrio anguillarum and Aeromonas salmonicida Subspecie achromogenes on Health and Survival of Turbot

“…Numerous vaccine formulations for the control of furunculosis [ 2 , 9 , 10 , 11 ] and vibriosis [ 2 , 9 , 12 , 13 , 14 , 15 , 16 ] in fish have been developed. In recent years most vaccine development programs have concentrated on multivalent products [ 10 , 17 , 18 , 19 ] and adjuvants [ 20 ] have become important tools for increasing vaccine potency. In fact, most of the vaccines commercially available are polyvalent oil-adjuvanted vaccines.…”