Atlantic salmon scale explants in bacteria-host interaction studies: in vitro challenge model

Area of Science:

• Aquaculture
• Immunology
• Fish Health

Background:

• Cell lines and primary cultures are common models for host-pathogen interactions.
• Live fish challenge trials are costly and raise ethical concerns.
• Atlantic salmon scale explants (SE) present a potential alternative model.

Purpose of the Study:

• To evaluate Atlantic salmon scale explants (SE) as a model for bacterial challenges.
• To compare immune gene expression in SE with other fish tissues.
• To investigate the immune response of SE to specific bacterial pathogens.

Main Methods:

• Transcriptomic analysis of SE compared to body map data.
• Exposure of SE to bacterial pathogens (Moritella viscosa, Tenacibaculum finnmarkense) and commensal bacteria.
• Analysis of immune gene expression, including chemokines, cytokines, and inflammatory markers.

Main Results:

• SE exhibit strong immune activity, ranking high in antiviral, antibacterial, and inflammatory gene expression.
• SE express high levels of skin-specific structural genes.
• Bacterial exposure upregulated a suite of immune genes in SE in a dose-dependent manner, indicating sentinel function.
• Distinct immune responses were observed between different bacterial species and in combination with commensal bacteria.

Conclusions:

• Atlantic salmon scale explants (SE) are a promising and ethically sound model for studying fish-bacterial interactions.
• SE function as immune sentinels, effectively mobilizing responses to bacterial encounters.
• Further research should include time-course studies and pathology detection for model refinement.