Avaliação de adjuvantes para formulação de vacina Brucella ovis gama-irradiada em modelo murino de infecção por Brucella ovis

Abstract

Brucellosis is an important infectious disease caused by coccobacilli, Gram-negative, facultative intracellular bacteria member of the genus Brucella. Ovine brucellosis, whose etiological agent is Brucella ovis, causes reproductive and economic losses in ovine herds worldwide. Vaccination of these animals represents an efficient method for infection control in countries where the incidence is considered high. The inactivated vaccines, although safer, may result in insufficient or ineffective immune responses. The aim of this study was to evaluate the association of a gamma-irradiated vaccine B. ovis ATCC 25840 with different adjuvants as a strategy to increase its immunogenicity and protection. The alginate and chitosan biopolymers, as well as the Montanide ISA 61 emulsion have been shown to incite an intense and long-lasting local response, especially when associated with the antigen. However, Montanide ISA 61 showed lower reactogenicity when compared to the others. Furthermore, the vaccine formulations B. ovis γ-irradiated coated alginate-chitosan and B. ovis γ-irradiated associated with Montanide ISA 61 induced high levels of IgG2b, an important marker of cellular immune response. Nevertheless, these formulations failed to provide protective immunity in mice experimentally challenged with the virulent strain of B. ovis.