• Vaccine Name: Recombinant chimera vaccine BLSOmp31
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0000413
• Type: Subunit vaccine
• Antigen: The antigen used in this vaccine is a chimerical protein containing parts of Brucella Lumazine Synthase (BLS) and an outer membrane protein of 31 kDa (Omp31).
• Preparation: Recombinant BLS (rBLS), rOmp31 and rBLSOmp31 were expressed in E. coli and purified as previously described (Laplagne et al., 2004). Purity was assessed by Coomassie blue stain, and recombinant proteins were adsorbed with Sepharose-polymyxin B to eliminate LPS contamination. The peptide was further purified by HPLC using a C-18 reverse phase column and the molecular weight was confirmed by mass spectroscopy (Laplagne et al., 2004).
• Virulence: None.
• Description: The chimerical protein BLSOmp31 is synthesized using parts of Brucella Lumazine Synthase (BLS) and an outer membrane protein of 31 kDa (Omp31), which have given limited protection in mouse models (Cassataro et al., 2007).

Mouse Response

• Vaccination Protocol: Mice (eight/group) were anaesthetized with methoxyfuorane and immunized by the intraperitoneal route with 30
• Immune Response: Immunization with recombinant BLSOmp31 elicited a strong specific IgG response that was detectable after the first immunization, increased after the second boost and reached IgG mean titers of 78,400 or 26,000 (anti-rOmp31 and anti-Omp31(48–74) , respectively) at the time of bacterial challenge. Immunizatio with rBLSOmp31 elicited high levels of anti-Omp31 IgG1 as well as IgG2a antibodies (IgG1 mean titer: 17,600; IgG2a mean titer: 5300). IgG1 titers predominated over IgG2a titers during the whole immunization schedule for both recombinant antigens. The elicited anti-peptide antibodies recognized the recombinant Omp31 as well as the native membrane protein, as demonstrated by the reactivity of the sera against whole rough B. ovis bacteria. These antibodies also produced complement mediated B. ovis cells lysis (Cassataro et al., 2007).
• Challenge Protocol: Immunized mice were challenged, by intravenous injection, with 1×10^4 B. melitensis H38S or 1×10^4 B. ovis. Mice were killed by cervical dislocation 30 days after being challenged and their spleens were removed aseptically. Each spleen was homogenized in a stomacher bag, serially diluted, plated on supplemented TSA yeast extract (TSA-YE) and incubated (Cassataro et al., 2007).
• Efficacy: The chimera significantly increases the protection elicited against B. ovis with respect to either BLS or Omp31. In fact, rBLSOmp31 induced the highest protection level (2.45 log) against B. ovis, which was only comparable with that induced by the control vaccine (2.42 log), but significantly higher (P < 0.01) than the vaccination with rBLS plus Omp31(48–74) (1.08 log) (Cassataro et al., 2007).