Deciphering the newly discovered branchial cavity immune surveillance system to protect fish against infectious diseases in aquaculture.

The sustainability of aquaculture, an important food source for human, is severely challenged by infectious diseases.

Unfortunately, the development of new therapies and vaccines is hindered by our incomplete understanding of the fish immune system.

The lack of knowledge of the mechanisms governing immune responses in the branchial cavity is particularly alarming considering that it represents a main port of entry for pathogens and is involved in many pathologies affecting farmed fish.

Recent findings of new lymphoid tissues, bound together by a previously unknown tonsil-like organ inside an even larger lymphoid network revealed the branchial cavity as an unsuspected important region of the fish immune system.

The main objective of this project is to characterize this newly discovered branchial cavity immune surveillance system to harness its potential against infectious diseases in aquaculture.

Toward this goal, the project will take advantage of the zebrafish model to achieve the following objectives: 1) Characterize the newly discovered lymphoid tissues and tonsil-like organ. 2) Decipher the rules of antigen sampling and transport in the branchial cavity. 3) Characterize the development of the branchial cavity lymphoid architecture. 4) Decipher the roles of the branchial cavity immune surveillance system in immune responses to infection and vaccines.

In a comparative effort, the project will then study the branchial cavity immune system in Atlantic salmon and other fish species relevant for aquaculture.

The methodology will combine sophisticated immunohistology, nanotechnologies, state-of-the-art transcriptomic analysis, antibody-assays, and advanced 3D microscopy.

The project will progress far beyond the current knowledge in fish immunology, which could drastically impact current paradigms in the field, open new perspectives for fish vaccination and diseases monitoring in aquaculture, and has the potential, in the long term, to positively impact human health.