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Oral immunization using alginate microparticles as a useful strategy for booster vaccination against fish lactoccocosis

Romalde, J.L., Luzardo-Alvarez, A., Ravelo, C., Torano, A.E., Blanco-Mendez, J.
Aquaculture 2004 v.236 no.1-4 pp. 119-129
Lactococcus garvieae, animal pathogenic bacteria, Oncorhynchus mykiss, trout, anadromous fish, fish culture, fish diseases, bacterial infections, disease prevention, oral vaccination, alginates, encapsulation
In this work, oral vaccination with encapsulated and non-encapsulated antigens was preliminary evaluated as alternative immunization procedures against trout lacotococcosis. Fish were oral immunized with a variety of different Lactococcus garvieae vaccines including encapsulated and non-encapsulated bacterial cells. An aqueous-based bacterin administered by intraperitoneal injection (i.p.) was employed as positive control. The best protective rates by oral immunization were obtained with the alginate-encapsulated vaccine (RPS of 50%); this, however, does not warrant the use of this formulation as primary immunization method. We also evaluated the efficacy of this alginate-encapsulated vaccine as booster immunization strategy. Fish were primary i.p. vaccinated with the aqueous-based vaccine and 3 months later were boostered with the oral vaccine. Four weeks after revaccination protection reached RPS values of 87%, which indicated the value of this encapsulated vaccine to increase the duration of the protection of rainbow trout against lacotoccosis.