The Brucella abortus S19 DeltavjbR live vaccine candidate is safer than S19 and confers protection against wild-type challenge in BALB/c mice when delivered in a sustained-release vehicle

• Published in: Infection and immunity 2009-02, Vol.77 (2), p.877
• Main Authors: Arenas-Gamboa, A M, Ficht, T A, Kahl-McDonagh, M M, Gomez, G, Rice-Ficht, A C
• Format: Article
• Language: English
• Subjects: Animals; Brucella abortus - genetics; Brucella abortus - immunology; Brucella Vaccine - administration & dosage; Brucella Vaccine - adverse effects; Brucella Vaccine - immunology; Brucella Vaccine - standards; Brucellosis - prevention & control; Delayed-Action Preparations; Female; Gene Deletion; Mice; Mice, Inbred BALB C; Mutation; Spleen - pathology
• ISSN: 1098-5522
• DOI: 10.1128/IAI.01017-08

Brucellosis is an important zoonotic disease of nearly worldwide distribution. Despite the availability of live vaccine strains for bovine (S19, RB51) and small ruminants (Rev-1), these vaccines have several drawbacks, including residual virulence for animals and humans. Safe and efficacious immunization systems are therefore needed to overcome these disadvantages. A vjbR knockout was generated in the S19 vaccine and investigated for its potential use as an improved vaccine candidate. Vaccination with a sustained-release vehicle to enhance vaccination efficacy was evaluated utilizing the live S19 DeltavjbR::Kan in encapsulated alginate microspheres containing a nonimmunogenic eggshell precursor protein of the parasite Fasciola hepatica (vitelline protein B). BALB/c mice were immunized intraperitoneally with either encapsulated or nonencapsulated S19 DeltavjbR::Kan at a dose of 1 x 10(5) CFU per animal to evaluate immunogenicity, safety, and protective efficacy. Humoral responses postvaccination indicate that the vaccine candidate was able to elicit an anti-Brucella-specific immunoglobulin G response even when the vaccine was administered in an encapsulated format. The safety was revealed by the absence of splenomegaly in mice that were inoculated with the mutant. Finally, a single dose with the encapsulated mutant conferred higher levels of protection compared to the nonencapsulated vaccine. These results suggest that S19 DeltavjbR::Kan is safer than S19, induces protection in mice, and should be considered as a vaccine candidate when administered in a sustained-release manner.