Humoral responses against P. salmonis in Atlantic salmon
Piscirickettsia salmonis is the causative agent of salmonid rickettsial septicaemia (SRS) in several salmonid species. This disease has been described in several countries, but is mainly problematic in Chile, where it endangers the salmon industry. No vaccines are currently available that elicit effective long term protection. The long-time goal of our collaboration (UiT and the vaccine company Vaxxinova) is to develop improved P. salmonis vaccines. An essential step for obtaining this goal is to understand the mechanisms promoting protective immunity against this pathogen. Humoral immunity against SRS are poorly described, understood and validated, and is a focus for our on-going studies.
The main objective for this experiment is to validate the ELISpot findings of the pilot experiment performed earlier this year. In that study, Atlantic salmon was challenged with P. salmonis by intraperitoneal injection (IP) of a Chilean field strain in order to set up a challenge model and to test a specific anti-P. salmonis ELISpot. The ELISpot was successfully developed and yielded very interesting results concerning the localization of specific (and total) antibody producing cells. These results will have to be reproduced in order to be scientifically valid. This will be done by challenging 64 fish and sampling for the ELISpot.
This experiment includes severe suffering in 40 fish due to challenge with a disease inducing mortalities. This distress will be limited by using humane endpoints. Furthermore, 24 fish will be injected with PBS and suffer mild distress.
The direct benefits of this experiment are validation of a new assay and insights into the immune responses and migration of immune cells that might lead to new vaccination strategies. The ELISpot assay could in some future cases replace live challenge with P. salmonis in vaccination trials, since the number of antibody producing cells might give an indication of the protection induced by vaccines. The reduction in the number of fish used for some future challenge trials would then overcome the costs of this single experiment.As part of the vaccination strategy experiment the indirect benefits are much higher. Currently there is no vaccine with long term effective protection against SRS, leading to many diseased fish with high mortalities in Chile. An effective vaccine with long term protection would reduce the suffering for most of these fish as well as significantly reduce the amount of of antibiotics used in Chilean aquaculture. These benefits far outweigh the costs of these experiments.
In this experiment, we will use 64 Atlantic salmon presmolts of 50 grams. Although no replacement is possible for this experiment, both reduction and refinement have been taken into account during design of the experiment. The number of fish per sample group were reduced to the minimum necessary to obtain valid results, based on the previous pilot study. Furthermore, with only three sample time points, a kinetics overview can be presented. Refinement lead to the inclusion of humane endpoints to minimize suffering and of multiple endpoints; not just the ELISpot measurement, but also ELISA and re-isolation.
The main objective for this experiment is to validate the ELISpot findings of the pilot experiment performed earlier this year. In that study, Atlantic salmon was challenged with P. salmonis by intraperitoneal injection (IP) of a Chilean field strain in order to set up a challenge model and to test a specific anti-P. salmonis ELISpot. The ELISpot was successfully developed and yielded very interesting results concerning the localization of specific (and total) antibody producing cells. These results will have to be reproduced in order to be scientifically valid. This will be done by challenging 64 fish and sampling for the ELISpot.
This experiment includes severe suffering in 40 fish due to challenge with a disease inducing mortalities. This distress will be limited by using humane endpoints. Furthermore, 24 fish will be injected with PBS and suffer mild distress.
The direct benefits of this experiment are validation of a new assay and insights into the immune responses and migration of immune cells that might lead to new vaccination strategies. The ELISpot assay could in some future cases replace live challenge with P. salmonis in vaccination trials, since the number of antibody producing cells might give an indication of the protection induced by vaccines. The reduction in the number of fish used for some future challenge trials would then overcome the costs of this single experiment.As part of the vaccination strategy experiment the indirect benefits are much higher. Currently there is no vaccine with long term effective protection against SRS, leading to many diseased fish with high mortalities in Chile. An effective vaccine with long term protection would reduce the suffering for most of these fish as well as significantly reduce the amount of of antibiotics used in Chilean aquaculture. These benefits far outweigh the costs of these experiments.
In this experiment, we will use 64 Atlantic salmon presmolts of 50 grams. Although no replacement is possible for this experiment, both reduction and refinement have been taken into account during design of the experiment. The number of fish per sample group were reduced to the minimum necessary to obtain valid results, based on the previous pilot study. Furthermore, with only three sample time points, a kinetics overview can be presented. Refinement lead to the inclusion of humane endpoints to minimize suffering and of multiple endpoints; not just the ELISpot measurement, but also ELISA and re-isolation.