Natural Feed Additives Modulate Immunity and Mitigate Infection with <i>Sphaerospora molnari</i> (Myxozoa: Cnidaria) in Common Carp: A Pilot Study
Vyara O. Ganeva,
Tomáš Korytář,
Hana Pecková,
Charles McGurk,
Julia Mullins,
Carlos Yanes-Roca,
David Gela,
Pavel Lepič,
Tomáš Policar,
Astrid S. Holzer
Affiliations
Vyara O. Ganeva
Biology Center of the Czech Academy of Sciences, Institute of Parasitology, 37005 České Budějovice, Czech Republic
Tomáš Korytář
Biology Center of the Czech Academy of Sciences, Institute of Parasitology, 37005 České Budějovice, Czech Republic
Hana Pecková
Biology Center of the Czech Academy of Sciences, Institute of Parasitology, 37005 České Budějovice, Czech Republic
Charles McGurk
Skretting Aquaculture Research Centre, 4016 Stavanger, Norway
Julia Mullins
Skretting Aquaculture Research Centre, 4016 Stavanger, Norway
Carlos Yanes-Roca
South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia, 37005 České Budějovice, Czech Republic
David Gela
South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia, 37005 České Budějovice, Czech Republic
Pavel Lepič
South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia, 37005 České Budějovice, Czech Republic
Tomáš Policar
South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia, 37005 České Budějovice, Czech Republic
Astrid S. Holzer
Biology Center of the Czech Academy of Sciences, Institute of Parasitology, 37005 České Budějovice, Czech Republic
Myxozoans are a diverse group of cnidarian parasites, including important pathogens in different aquaculture species, without effective legalized treatments for fish destined for human consumption. We tested the effect of natural feed additives on immune parameters of common carp and in the course of a controlled laboratory infection with the myxozoan Sphaerospora molnari. Carp were fed a base diet enriched with 0.5% curcumin or 0.12% of a multi-strain yeast fraction, before intraperitoneal injection with blood stages of S. molnari. We demonstrate the impact of these treatments on respiratory burst, phagocytosis, nitric oxide production, adaptive IgM+ B cell responses, S. molnari-specific antibody titers, and on parasite numbers. Both experimental diets enriched B cell populations prior to infection and postponed initial parasite proliferation in the blood. Curcumin-fed fish showed a decrease in reactive oxygen species, nitric oxide production and B cell density at late-stage infection, likely due to its anti-inflammatory properties, favoring parasite propagation. In contrast, multi-strain yeast fraction (MsYF)-fed fish harbored the highest S. molnari-specific antibody titer, in combination with the overall lowest parasite numbers. The results demonstrate that yeast products can be highly beneficial for the outcome of myxozoan infections and could be used as effective feed additives in aquaculture.