CpG inclusion in feed reduces sea lice, Lepeophtheirus salmonis, numbers following re-infection
Version of Record online: 20 NOV 2012
© 2012 Blackwell Publishing Ltd
Journal of Fish Diseases
Special Issue: Papers from the 9th International Sea Lice Conference Bergen, 20–23rd May 2012
Volume 36, Issue 3, pages 229–240, March 2013
How to Cite
Purcell, S. L., Friend, S. E., Covello, J. M., Donkin, A., Groman, D. B., Poley, J. and Fast, M. D. (2013), CpG inclusion in feed reduces sea lice, Lepeophtheirus salmonis, numbers following re-infection. Journal of Fish Diseases, 36: 229–240. doi: 10.1111/jfd.12024
- Issue online: 14 FEB 2013
- Version of Record online: 20 NOV 2012
- Manuscript Accepted: 19 SEP 2012
- Manuscript Revised: 12 SEP 2012
- Manuscript Received: 10 JUL 2012
- Novartis Animal Health Ltd.
- NSERC engage program
- Springboard Atlantic
- Northeast Nutrition
- Cooke Aquaculture Ltd.
- Aquatic Animal Facilities and staff at AVC-UPEI
- Atlantic salmon;
- interleukin 12β;
- Lepeophtheirus salmonis ;
- matrix metalloproteinase-9
Lepeophtheirus salmonis infections in Atlantic salmon, Salmo salar, have been characterized by little to no hyperplastic response and a biphasic immune response that results in chronic inflammation with tissue repair as the infection progresses. We hypothesized that CpG administration with prior lice exposure would enhance epithelial inflammatory mechanisms and boost the Atlantic salmon immune response to L. salmonis, leading to greater protection against infection. We administered multiple exposures of L. salmonis to two groups of Atlantic salmon and compared responses against first-time exposed Atlantic salmon. Following re-exposure, CpG fed fish exhibited increased skin expression of interleukin (IL)-1β and IL-12 β compared to control previously exposed (CPE) and control first-time exposed (CFE) animals, respectively. This inflammatory enhancement occurred with significantly lower expression of matrix metalloproteinase-9 (MMP 9), both systemically (spleen) and locally (skin). Reduced MMP 9 expression was a hallmark of the re-infected fish (occurred in both tissues at both times). When significant differences were present in the skin or spleen, the two re-exposed groups showed greater similarity than with the first exposure group. Lice numbers on CpG fed fish were significantly lower than CFE fish at 7 days post-re-infection (dpri), and although they were not significantly different at 17 dpri, the trend of lower lice levels remained. CpG fed fish also showed nearly twofold greater protection than CPE when compared to the CFE group (48.5% vs. 27.0% reductions at 7 dpri and 27.2% vs. 13.1% reductions at 17 dpri, respectively). The enhanced protection of CpG oligodeoxynucleotide administration to previous exposure was consistent across all body surfaces and suggests that CpG can not only enhance innate responses to L. salmonis in Atlantic salmon, but also further stimulate adaptive responses.