Updates on the research on nanocarriers in fish vaccine oral, immersion and injection delivery: A major review.

Fish farming is facing severe challenges from frequent disease outbreaks with the intensification and high-density development of aquaculture. Vaccination, as a green and efficient disease prevention and control strategy, relies heavily on delivery efficiency for its effectiveness. Currently, fish vaccines are primarily administered through injection, immersion, and oral vaccination. However, challenges such as antigen inactivation in water, degradation in the digestive tract after oral and immersion vaccination, and low mucosal adhesion and penetration efficiency have significantly limited the application of immersion and oral vaccines. Nanocarriers have emerged as a critical research direction for fish vaccine delivery due to their unique physicochemical properties, such as excellent biocompatibility, antigen protection capabilities, and mucosal adhesion. This review systematically summarizes the research progress on nanocarriers for fish vaccine delivery across different vaccination methods including oral, immersion, and injection, with a focus on analyzing the preparation methods, characteristics, and delivery efficacy of various nanocarriers for different vaccine types. The review further explores the current challenges and limitations in the field and provides insights into the future development directions of nano-delivery systems, promoting the green and sustainable development of aquaculture.