Antigen uptake and immune responses after immersion vaccination

Area of Science:

• Aquatic immunology
• Fish health management
• Vaccination technologies

Background:

• Immersion vaccination is a practical mass vaccination method for fish.
• The precise mechanisms of antigen uptake and protective immunity remain largely unknown.
• Various factors influence antigen uptake, with antigen concentration being critical.

Purpose of the Study:

• To investigate the primary site of antigen uptake during immersion vaccination in fish.
• To identify the cell types involved in antigen uptake.
• To explore the relationship between antigen uptake and immune protection.

Main Methods:

• Quantitative study of antigen uptake using immersion vaccination techniques.
• Analysis of antigen entry sites, including skin, gills, lateral line, and gut.
• Identification of cellular players in antigen uptake, considering antigen properties.

Main Results:

• The skin was identified as the principal site for antigen uptake during immersion vaccination.
• Uptake rates on the lateral line and general skin surface were comparable.
• Both phagocytes and various epithelial cells were found to be involved in antigen uptake.
• Cellular involvement varied based on antigen's physical state and entry site.

Conclusions:

• Skin is the main site for antigen uptake in fish immersion vaccination.
• Epithelial cells and phagocytes play key roles in antigen uptake.
• The role of humoral immunity in protection is controversial, suggesting potential importance of cell-mediated or local immunity.