Use of adjuvanted vaccines to lengthen the protection against lactococcosis in rainbow trout (Oncorhynchus mykiss)

In this work, we evaluated the effect of the inclusion of different adjuvants in the vaccine formulation against Lactococcus garvieae in comparison with an aqueous bacterin. The aqueous and non mineral oil adjuvanted vaccines (Montanide-ISA-763-A and Aquamun) yielded a good protection 4 weeks after the immunization (RPS of 82.6, 84.8 and 86.9, respectively). The protective rates obtained for the adjuvants Montanide-IMS-2212 (water based nanoparticles with immunostimulant) and Carbomer (high molecular weight polymer organic of polyacrylic acid) were 45.7% and 56.5%, respectively. We also evaluated the duration of protection confered by Aquamun adjuvanted-vaccine in comparison with the aqueous bacterin. Three months after vaccination, the RPS values obtained with the aqueous vaccine was 40% whereas with the Aquamun adjuvanted-vaccine the protection increased to values of 92%. In addition, a long lasting protection was observed with this adjuvanted vaccine with RPS values of 90% and 83.3% in the challenges performed at 6 and 8 months post-vaccination, respectively.