Su F.-JMEEI-MEI CHEN2022-04-252022-04-2520222076393Xhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85123999993&doi=10.3390%2fvaccines10020207&partnerID=40&md5=b2c069841f3de62a460c4200c4c74210https://scholars.lib.ntu.edu.tw/handle/123456789/605980Photobacterium damselae subsp. damselae is a pathogen that mainly infects a variety of fish species. There are many antibiotic-resistant strains of Photobacterium damselae subsp. damselae. In a previously published article, we described the production method for a novel oral biofilm vaccine. In the study reported herein, we confirmed the protective effect of the oral biofilm vaccine against Photobacterium damselae subsp. damselae. Twenty-eight days after vaccination, phagocytosis increased by 256% relative to the control group. The mean albumin–globulin ratios of the vaccine groups were significantly lower than the mean albumin–globulin ratios of the control group. There were no significant intergroup differences in lysozyme activity. Mean IgM titers were significantly higher in the vaccine group than in the control group. There was a significant upregulation of the TLR 3, IL-1β, and IL-8 genes in the spleen 28 days after vaccination. The cumulative mortality of the control fish was 84% after challenging fish with the Photobacterium damselae subsp. damselae, while the cumulative mortality of the oral biofilm vaccine (PBV) group was 32%, which was significantly higher than those of the whole-cell vaccine (PWV) and chitosan particle (CP) groups. There is minimal published research on the prevention and treatment of Photobacterium damselae subsp. damselae infection; therefore, this oral biofilm vaccine may represent a new method to fill this gap. ? 2022 by the authors. Licensee MDPI, Basel, Switzerland.Epinephelus lanceolatusOral biofilm vaccinePhotobacterium damselae subsp. damselaecell-based vaccinecytokinegamma interferonimmunoglobulin Aimmunoglobulin enhancer binding proteinimmunoglobulin Minterleukin 10interleukin 1betainterleukin 4interleukin 6interleukin 8lysozymeRNA 16Stoll like receptor 3tumor necrosis factoraffinity chromatographyanimal experimentantibiotic resistanceantibody responseaquacultureArticlebacterial infectionbacterial strainbacteriophagebiofilmcell viabilitycontrolled studyenzyme activityenzyme linked immunosorbent assayenzyme linked immunospot assayEpinephelusEscherichia colifishgene expressionhumoral immunityimmune responseinnate immunityintestine floraLactobacillus caseiLactobacillus plantarumLactococcus garvieaemortalitynonhumanphagocytosisPhotobacteriumPhotobacterium damselaepolyacrylamide gel electrophoresispolymerase chain reactionreal time polymerase chain reactionscanning electron microscopysurface propertysurvival rateupregulationvaccination[SDGs]SDG3journal article10.3390/vaccines100202072-s2.0-85123999993