Abstract
Most infectious agents colonize the host through mucosal surfaces. Hence, blocking the pathogen at these initial entry and replication sites is a logical strategy to efficiently prevent infection from further spreading throughout the host and developing a more severe form of disease. Mucosal immunization has been shown to elicit the most effective protective responses at these mucosal surfaces. As such, the interest and demand for development of mucosal vaccines have increased in the recent years. In fish, oral vaccination provides the added benefit of ease in mass administration. Despite these clear advantages, there are only a few commercially available mucosal vaccines for fish to date. To address this issue, the MucoProtect project aims to develop a novel and versatile vaccine delivery system that is customized for salmon. Alginate nanoparticles used as vaccine carriers were prepared by an emulsion method. Using bovine serum albumin (BSA) as our test antigen, production of BSA-loaded nanoparticles was optimized in relation to variations in particle synthesis parameters to give the highest encapsulation efficiency of the antigen. BioPlex and ELISA assays developed for detection of BSA-specific antibodies have shown that our candidate nanoparticle vaccine preparation can induce good antibody responses in Atlantic salmon following direct systemic and mucosal stimulations via intraperitoneal injection and anal intubation, respectively. In addition, these nanoparticles did not show any toxic effects when tested in vitro using the rainbow trout cell line, RTgut-GC. Ability of our candidate oral vaccine to stimulate relevant immune responses when incorporated into feeds will be tested and optimized in in vivo feeding trials.