Changes in Serum Biomarkers of Oxidative Stress in Cattle Vaccinated with Tick Recombinant Antigens: A Pilot Study

Tick vaccination is an environmentally friendly alternative for tick control, pathogen infection, and transmission. Tick vaccine protection is sometimes incomplete, which may be due to problems in the stability, conformation, and activity of antibodies. This might be related to oxidative stress, but more studies are needed about the possible relationships between oxidative stress and immune function. The objective of this study was to evaluate and compare various serum biomarkers of antioxidant response and oxidative damage in cattle vaccinated with two recombinant antigens, the chimera of Subolesin- BM95 (homologue antigen of BM86)-MSP1a and BM86, and a control consisting in the adjuvant of the vaccines. Cupric reducing antioxidant capacity (CUPRAC), ferric reducing ability of the plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), total thiol concentrations, and uric acid were evaluated in serum to determine the antioxidant response. To evaluate oxidative status, ferrous oxidation-xylenol orange (FOX), total oxidant status (TOS), advanced oxidation protein products (AOPP) and hydrogen peroxide (H₂O₂) concentrations in serum were determined. In addition, correlations between biomarkers of oxidative stress and antibody titers were evaluated. A significant decrease in all antioxidant biomarkers, with exception of thiol, and also a decrease in the oxidant markers TOS, AOPP and H₂O₂ was observed in cattle vaccinated with BM86, that also showed the highest antibody titers response whereas no significant differences in any of the biomarkers were detected in the Subolesin-Bm95-MSP1a and control groups. In addition, the dynamics of Cuprac and H₂O₂ with time showed significant differences between the groups. Although this is a pilot study and the results should be interpreted with caution and corroborated by studies involving a large number of animals, our results indicate that, in our experimental conditions, those vaccines able to induce a lower oxidative stress produce a higher concentration of antigen-specific antibodies. Overall, the results of the study provided information on the behavior of different biomarkers related to antioxidant defense, and the oxidative damage in cattle in response to vaccination.