The Candidate Vaccine Strainbrucella Ovis Increment Abcbais Protective Againstbrucella Melitensisinfection In Mice

Brucellosis is a major zoonotic disease, andBrucella melitensisis the species most often associated with human infection. Vaccination is the most efficient tool for controlling animal brucellosis, with a consequent decrease of incidence of human infections. Commercially available live attenuated vaccines provide some degree of protection, but retain residual pathogenicity to human and animals. In this study,Brucella ovis increment abcBA(Bo increment abcBA), a live attenuated candidate vaccine strain, was tested in two formulations (encapsulated with alginate and alginate plus vitelline protein B [VpB]) to immunize mice against experimental challenge withB. melitensisstrain 16M. One week after infection, livers and spleens of immunized mice had reduced numbers of the challenge strainB. melitensis16M when compared with those of nonimmunized mice, with a reduction of approximately 1-log(10)ofB. melitensis16M count in the spleens from immunized mice. Moreover, splenocytes stimulated withB. melitensisantigensin vitrosecreted IFN-gamma when mice had been immunized withBo increment abcBAencapsulated with alginate plus VpB, but not with alginate alone. Body and liver weights were similar among groups, although spleens from mice immunized withBo increment abcBAencapsulated with alginate were larger than those immunized withBo increment abcBAencapsulated with alginate plus VpB or nonimmunized mice. This study demonstrated that two vaccine formulations containingBo increment abcBAprotected mice against experimental challenge withB. melitensis.