Investigating the possibilities of using superoxide dismutase 1 isoenzyme forms as biomarkersfor intensities of parasitic infections in sheep

Abstract

In clinical pathology of sheep, parasitic infections occupy a significant place and besides health, pose a great economic problem in sheep breeding. Sheep are highly susceptible to parasitic infections, even under conditions of very low pasture infections. In this way, sheep support the sustainability and amplification of parasitic fauna intensity in an epizootiological region and may at the same time serve as “indicators” of animal species with the aim of evaluating the presence of parasitic fauna in a specific region. The evaluation of parasitic infection intensity in the host is of special significance, primarily for the therapeutic measures necessary to be taken, but also, represents an essential criterion employed in selecting more resistant individuals. The presence of parasites and their developing forms during migration, leads to health disturbances in the animals, when the degree of damage is in direct correlation with the number of parasites present and/or their larval forms, ie. with the intensity of parasitic infection. Free radical species originating during parasitic infections, directly inhibit some of the antioxidative enzymes. Changes on these enzymes and their inhibition have an influence on the protective capacity from oxidative damages and a relative participation of certain components in the total antioxidative potential. For this reason, the hypothesis has been established that the analysis of these changes may serve as a diagnostic tool with the aim of determining the intensity of parasitic infection. SOD (EC 1.15.1.1) presents the first line of defense under conditions of disturbed redox balance, as they prevent the formation of a series of very harmful reactive oxygen and nitrogen species (hydroxyl radicals and peroxynitrites) and the initiation of oxidative chain reactions, which as an outcome are significant damages to biomolecules (lipids, proteins and nucleic acids). A known “paradox” is that SOD 1 is irreversably inactivated at high concentrations of hydrogen peroxide, which is a product of the reaction catalyzed by this enzyme. Considering the previously elaborated fact that parasitic infections lead the organism of the host into oxidative stress, the aim of this doctoral thesis was to more precisely investigate changes in the isoenzymatic profile of SOD 1 in sheep and examine if these may serve as biomarkers for the intensity of parasitic infection. The study was performed on a total of 300 sheep (aged 12 to 18 months), on strains of autochtonous Zackel sheep breed (Sjenicko-pesterska, Lipska and Vlaska vitoroga) which are included in the programme for conserving animal genetic resources in the Republic of Serbia as well as on imported breeds of sheep (Wurtemberg, Ile de France and Charollais) kept under semi intensive conditions in four regions. Within each investigated breed/strain, a control group of sheep was established (n=10), negative to parasitic infection. Sampling of feces for parasitological and blood for biochemical assaying was performed during the course of three…