PRE2023-VACUNAS ORALES CONTRA IPNV EN TRUCHA BASADAS EN ESPORAS DE B. SUBTILIS Y MICROPARTICULAS DE FLAGELINA (PID2022-140624OR-I00)

The biggest threat to the aquaculture industry is to face losses due to disease outbreaks. Vaccines are the most useful and cost- effective method to generate a good protection against pathogens. In spite of all the progress achieved, approved vaccines for aquaculture are still costly, cause stress due to fish handling, and are only relatively efficient. Traditionally, vaccines stimulate a systemic immune response with an intra-muscular or intra-peritoneal injection. However, the main route of exposure to aquatic pathogens are the mucosal epithelia, that have an associated lymphoid tissue (MALT) of which not all response mechanisms are known in detail in the trout. Oral vaccine administration together with feed seems to be the best method, because it is more versatile for the immunization against a wider range of pathogens, allows to vaccinate high numbers of fish at a time (mass vaccination), and reduces fish stress and costs to the minimal. In this sense, Bacillus subtilis and flagellin could be used in trout as vaccine platforms delivered with feed. B. subtilis has the capacity to produce spores and flagellin can form microspheres with alginate. Our main hypothesis is that oral VP2 vaccines delivered by Bacillus subtilis spores and flagellin can reach the intestine, being adjuvant itself for mounting a strong mucosal and systemic, humoral (antibodies) and cellular (B, Th1, Th2, Th17) immune response.