Potencial vacinal da Brucella ovis ΔabcBA encapsulada com alginato contra a infecção por Brucella canis e sua inocuidade em cães

Abstract

Canine brucellosis is an infectious and zoonotic disease with worldwide distribution and is considered neglected. The infection is caused by Brucella canis, a Gram-negative bacterium that results in unspecific clinical signs in dogs and chronic disease in humans. Vaccination is most important tool for controlling brucellosis, but currently there is no vaccine available for canine brucellosis. This study aimed to evaluate protection and immune response induced by Brucella ovis ∆abcBA (Bo∆abcBA) encapsulated with alginate against the challenge with B. canis in mice and to assess the safety of this strain for dogs. The intracellular kinetics in primary canine and sheep macrophages was similar, with the wild strains B. ovis and B. canis being able to multiply in the intracellular medium, while the Bo∆abcBA vaccine strain showed an attenuated profile in these cells. Immunization of BALB/C mice with alginate-encapsulated Bo∆abcBA (108 CFU – colony forming units) induced lymphocyte proliferation, production of IL10 and IFN-γ, and protected against experimental challenge with B. canis. Dogs immunized with alginate-encapsulated Bo∆abcBA (109 CFU) seroconverted, and had no hematologic, biochemic or clinical changes. Furthermore, Bo∆abcBA was not detected by isolation or PCR with blood, semen, urine samples or vaginal swabs at any time point over the course of this study. Bo∆abcBA was isolated from lymph nodes near to the site of inoculation in two dogs at 22 weeks post immunization. In conclusion, encapsulated Bo∆abcBA protected mice against experimental B. canis infection, and it is safe for dogs.