P5-01 Evaluation of different adjuvants associated with vaccination candidate Brucella ovis ∆abcBA in a murine model of infection by Brucella ovis

Abstract

Brucellosis is an infectious disease caused by facultative intracellular Gram-negative bacteria, of great importance in animal and human health. Among the known species, Brucella ovis is capable of infecting sheep, mainly causing epididymitis and reproductive failure in ram, leading to important economic losses, thus highlighting the need to develop vaccines to help control this disease. Previous studies have shown good levels of protection againstB. ovis infection both in a murine model and in the natural host using the B. ovis ΔabcBA strain abcBA encapsulated by alginate. Therefore, this study aimed to evaluate the increase in the vaccine potential of the candidate B. ovis ΔabcBA associated with different adjuvants, polymeric matrix or alginate microcapsule and Chitosan, in mice challenged with B. ovis. We observed that B. ovis ΔabcBA encapsulated by alginate with chitosan, but not associted to polimeric matrix favored lower bacterial recovery in both the spleen and liver of challenged animals, demonstrating better efficacy in controlling the infection. It should also be noted the ability of this vaccine formulation to lead to a greater synthesis of immunoglobulin production, especially immunoglobulin G, where this increase in total levels is correlated with the increase in certain subclasses, with a significant emphasis on the higher levels of the IgG2a subclass, involved inthe favoring the control of infections by intracellular agents. Addicionally, use of this vaccine formulation resulted in lower score of histopathological lesions in target organs. These results demonstrate the vaccine potential of the B. ovis ΔabcBA strain encapsulated by alginate with chitosan, leading to both a higher protection index, as well as inducing the significant production of antibodies related to a protective immune response, making possible its future evaluation in a natural host.