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.
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.
Arenas-Gamboa
A M
AM
Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77845-1114, USA. aarenas@cvm.tamu.edu
Ficht
T A
TA
Kahl-McDonagh
M M
MM
Gomez
G
G
Rice-Ficht
A C
AC
D000818:Animals; D002004:Brucella Vaccine / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology* / Q000592:standards*; D002003:Brucella abortus / Q000235:genetics* / Q000276:immunology; D002006:Brucellosis / Q000517:prevention & control*; D003692:Delayed-Action Preparations; D005260:Female; D017353:Gene Deletion; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D013154:Spleen / Q000473:pathology
D002004:Brucella Vaccine; D003692:Delayed-Action Preparations