“Development of oral vaccines for aquaculture using spore-display technology (7236)”

development of oral vaccines for aquaculture using spore-display technology

Oral vaccines are highly demanded by the aquaculture sector to allow mass delivery of antigens. Despite this, most commercially available vaccines are injectable, being labor-intensive, expensive, and require individual handling of fish.One possible strategy to create injection-free vaccine delivery vehicles is the use of bacterial spores,extremely resistant structures with wide biotechnological applications.Bacterialspores, particularly those ofBacillus subtilis, are promising delivery vehicles of different molecules through surface display technology. Theextreme resistance of B. subtilisspores, which guarantees passagethrough the harsh gut environmentwithout losing characteristics, is the basis for their oral applications.Spores’ direct incorporation into animal feed, circumventing further protection processes, such as encapsulation, together with their simple production andlong shelf-lifewithout the need for refrigeration, are also attractive characteristics from the industrial point of view. Adding to this “needle-free” and “refrigeration-free” potential,B. subtilisspores adjuvant propertiesand contribution to GALT development,increase their potential as oral delivery systems of antigens.In this work,we displayed at the surface ofB. subtilisspores, antigens from different problematic aquaculture pathogens (e.g.,Vibriospp.,Photobacterium damselae, Edwrdsiella tarda,Aeromonas hydrophila).The developed Sporovaccines were first tested by immersion in zebrafish larvae (Danio rerio). When previously treated with the antigens-carrying spores,zebrafish survival upon a bacterial challenge with each pathogen, increased up to 90% depending on the pathogen targeted.Further, when added to commercial feed and used to orally vaccinate European seabass juveniles, Sporovaccines increased fish survival from 60 to 86%. We then evaluated the effecton the expression of immune-related genes by using an epithelial gut cell line from rainbow trout (Oncorhynchus mykiss)(RTgutGC cell line). Transcription effects were evaluated by real-time quantitative PCR analysis of immune-related genes (e.g., TNF-α,IL-1β,IL-8, COX-2, Hsp70, Casp3a2). Sporovaccines significantly induced the transcription of the pro-inflammatory cytokine IL-1βand pro-inflammatory chemokine IL-8.Our results indicate thatB. subtilisspores can effectively be used as carriers for massive delivery of antigens in fish. This work was funded byFEDER, POCI, PT2020, and FCT/MCTES through project PTDC/CVT-CVT/2477/2021, PhD fellowship 2021.07724.BD (GG), CIIMAR Strategic Funding UIDB/04423/2020 and UIDP/04423/2020.

1. SERRA, CLAUDIA, CIIMAR-UP, Presenter
2. Gonçalves, Gabriela, CIIMAR-UP, Author
3. Santos, Rafaela, CIIMAR-UP, Author
4. Carvalho, Antonio Paulo, CIIMAR-UP, Author
5. Enes, Paula, CIIMAR-UP, Author
6. Díaz-Rosales, Patricia, CIIMAR-UP, Author
7. Couto, Ana, CIIMAR-UP, Author
8. Oliva-Teles, Aires, CIIMAR-UP, Author