Development and evaluation as vaccines in mice of Brucella melitensis Rev.1 single and double deletion mutants of the bp26 and omp31 genes coding for antigens of diagnostic significance in ovine brucellosis.
The live attenuated Brucella melitensis Rev.1 strain is considered the best vaccine available for the prophylaxis of brucellosis in sheep caused by either B. melitensis or Brucella ovis. However, its application stimulates antibody responses in vaccinated animals indistinguishable by the current conventional serological tests from those observed in infected animals. The periplasmic protein BP26 and the outer membrane protein (OMP) Omp31 are immunodominant antigens in the serological responses of B. melitensis and B. ovis infected sheep, respectively. Accordingly, vaccine strain Rev.1 single and double deletion mutants of the bp26 and omp31 genes were developed, based on the principle that the use of such mutants as vaccines in association with diagnostic tests based on BP26 and Omp31 antigens would allow the serological differentiation between infected and vaccinated animals. The deletion mutants obtained were indistinguishable from the parental Rev.1 strain by conventional bacteriological and typing tests. The expression of their major surface antigens, as determined by reactivity with specific monoclonal antibodies (MAbs), remained unaffected, i.e. smooth-lipopolysaccharide (S-LPS) and OMPs besides in the expression of the antigens whose respective genes were deleted. The bp26 and omp31 deletions did not modify the kinetics of splenic infection nor the residual virulence of Rev.1 in the BALB/c mouse model. Vaccination of BALB/c mice with the deletion mutants conferred significant protective immunity against B. melitensis strain H38 or B. ovis strain PA challenges, to the same extent as that induced by parental Rev.1 strain. Thus, these Rev.1 bp26 or omp31 deletion mutants are promising vaccine candidates against B. melitensis and B. ovis infections and will be further evaluated in sheep.
Cloeckaert
Axel
A
Laboratoire de Pathologie Infectieuse et Immunologie, Unité BioAgresseurs Santé et Environnement, Institut National de la Recherche Agronomique, Nouzilly 37380, France. cloeckae@tours.inra.fr
Jacques
Isabelle
I
Grilló
Maria Jesus
MJ
Marín
Clara M
CM
Grayon
Maggy
M
Blasco
Jose-Maria
JM
Verger
Jean-Michel
JM
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000942:Antigens, Bacterial / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D002004:Brucella Vaccine / Q000235:genetics*; D017347:Brucella melitensis / Q000235:genetics* / Q000276:immunology*; D002006:Brucellosis / Q000276:immunology* / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D005260:Female; D008070:Lipopolysaccharides / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation / Q000235:genetics* / Q000276:immunology*; D017384:Sequence Deletion
D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; C106040:BP26 protein, Brucella; D001425:Bacterial Outer Membrane Proteins; D002004:Brucella Vaccine; D000939:Epitopes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; C101108:Omp31 protein, Brucella melitensis