Immunogenicity of a chimeric subcellular vaccine in ovine brucellosis

SILVIA. M ESTEIN, MARÍA A FIORENTINO, FERNANDO A. PAOLICCHI, JULIANA CASSATARO, GUILLERMO GIAMBARTOLOMEI, VANESA ZYLBERMAN, CARLOS A. FOSSATI, FERNANDO A. GOLDBAUM

VETERINARY IMMUNOLOGY AND IMMUNOPATHOLOGY

Elsevier

Lugar: Amsterdam, Holanda; Año: 2009 vol. 128 p. 227 - 228

0165-2427

Brucella ovis causes an infectious disease in sheep  characterized by epididymitis and infertility in rams and abortion in ewes. Vaccination programs are the only viable  means for the control of B. ovis in countries with a high incidence. B. melitensis Rev.1 is considered the best vaccine for  the prophylaxis of ovine brucellosis but has important disadvantages. Accordingly, research is under way to develop  effective subcellular vaccines. Detergent-extracted recombinant Omp31 from B. melitensis was previously identified  as a protective immunogen against B. ovis in rams. Moreover, our previous results demonstrate that a chimera  of Brucella lumazine synthase (BLS) that contains an immunodominant epitope of Omp31 delivered as a protein  (BLS-Omp31) or plasmidic DNA vaccine (pCIbls-Omp31) conferred protection against B. ovis infection in mice. In  this work, we evaluated the immunogenicity of these vaccines in rams using different strategies of immunisation.  Seventy rams 4–5-month-old were randomly distributed in following groups of immunisation: (G1) BLS-Omp31 in  Freund’s incomplete adjuvant (FIA), (G2) BLS-Omp31 in QUIL A adjuvant, (G3) pCIbls-omp31 with electroporation  (INOVIO, Norway), (G4) pCIbls-omp31 without electroporation, (G5) Prime-boost, (G6) HS (hot saline) extract in  FIA, (G7) PBS. Animals were vaccinated three times, four weeks apart. G5 received four injections (DNA primeprotein  boost). Rams were bled after each immunization. Antibody responses in serum were evaluated in indirect  ELISA against BLS-Omp31. Immunisation with the protein chimera formulated with adjuvant induced IgG specific  antibodies significantly higher than chimerical DNA vaccine. However, humoral immune responsewas enhanced in  electroporated sheep. Combination of a plasmidDNA priming step followed by a boost with the homologous protein  resulted in improved humoral antigen-specific response. These results indicate that the chimerical subunit vaccine  was immunogenic in rams and would be considered as potential vaccine in ovine brucellosis.