Protective efficacy of a Brucella vaccine using a Salmonella-based delivery system expressing Brucella Omp3b, BCSP31, and SOD proteins against brucellosis in Korean black goats.

This study aimed to assess the protective efficacy of a novel Brucella vaccine formulation in goats. Twenty black goats were separated into 2 groups. Group A was injected with 3.0 × 109 CFU (colony-forming units)/mL of a Salmonella-based delivery system harboring only vector (pMMP65). Group B was immunized with 3.0 × 109 CFU/mL of the vaccine, a mixture of 3 Brucella vaccine strains (using a Salmonella-based delivery system) expressing each recombinant B. abortus Omp3b, BCSP31, and SOD protein. No Salmonella delivery strain was isolated from all tested lymph nodes and parenchymal organs. Serum immunoglobulin (Ig) G titers and interferon gamma concentrations were significantly higher in group B than those in group A. After intraconjunctival challenge with virulent B. abortus strain 544, 40% of the vaccinated animals in group B were protected against B. abortus infection. The infection index and colonization of B. abortus in tested tissues was significantly lower in group B than group A. We conclude that this Brucella vaccine induces significant antigen-specific immune responses and provides effective protection against B. abortus infection in goats. Further studies are needed to enhance the protection rate of this Brucella vaccine and to discover its practical application in small ruminants.

La présente étude visait à évaluer l'efficacité protectrice d'une nouvelle formulation de vaccin contre Brucella chez les chèvres. Vingt chèvres noires furent séparées en deux groupes. Le Groupe A reçut par injection 3,0 × 109 unités formatrices de colonies (UFC)/mL de Salmonella servant de système de livraison ne contenant seulement que le vecteur (pMMP65). Le groupe B fut immunisé avec 3,0 × 109 UFC/mL du vaccin, un mélange de trois souches vaccinales de Brucella (utilisant le système de livraison à base de Salmonella) exprimant chaque protéine recombinante Omp3b, BCSP31, et SOD de B. abortus. Aucune bactérie Salmonella du système de livraison ne fut isolée des ganglions lymphatiques et organes testés. Les concentrations sériques d'immunoglobulines G (IgG) et d'interféron gamma étaient significativement plus élevées dans le groupe B que dans le groupe A. À la suite d'une infection défi par voie intra-conjonctivale avec une souche virulente de B. abortus (544), 40 % des animaux vaccinés dans le groupe B étaient protégés contre l'infection par B. abortus. L'index d'infection et de colonisation par B. abortus dans les tissus testés étaient significativement plus faible dans le groupe B comparativement au groupe A. Nous avons conclu que ce vaccin contre Brucella induisait des réponses immunes spécifiques d'antigène significatives et fournissait une protection efficace contre l'infection par B. abortus chez les chèvres. Des études additionnelles sont requises afin d'augmenter le taux de protection de ce vaccin (Brucella) et pour découvrir son application pratique chez les petits ruminants.(Traduit par Docteur Serge Messier).

Protective efficacy of an inactivated Brucella abortus vaccine candidate lysed by GI24 against brucellosis in Korean black goats.

The efficacy of GI24-lysed Brucella abortus cells as a vaccine candidate against brucellosis in goats was evaluated on 2 groups of Korean black goats. Group A goats were immunized subcutaneously (SC) with sterile phosphate-buffered saline, whereas group B goats were immunized SC with approximately 3 × 109 lysed B. abortus cells. Subcutaneous immunization with the lysed cells did not cause any negative impact on the overall clinical status, such as behavior and appetite, throughout the study period. The enzyme-linked immunosorbent assay (ELISA) optical densities values for B. abortus lipopolysaccharide in serum were considerably higher in group B than those in group A. Also, the levels of the cytokines interleukin 4 (IL-4), tumor necrosis factor-alpha (TNF-α), and interferon gamma (IFN-γ) were significantly elevated in group B compared with those in group A. Following intraconjunctival challenge with B. abortus strain 544, the severity of brucellosis in terms of infection index and colonization of B. abortus in tissues was significantly lower in group B than in group A. The present study concluded that 3 of 5 goats immunized with GI24-lysed bacteria were completely protected against challenge. Future investigations are required to improve the protective efficacy offered by lysed B. abortus cells for practical applications in small ruminants.

L'efficacité de cellules lysées de Brucella abortus GI24 comme vaccin candidat contre la brucellose chez les chèvres a été évaluée chez deux groupes de chèvres noires coréennes. Les chèvres du groupe A ont été immunisées par voie sous-cutanée (SC) avec de la saline tamponnée stérile, alors que les chèvres du groupe B ont été immunisées SC avec environ 3 × 109 cellules lysées de B. abortus. L'immunisation sous-cutanée avec les cellules lysées n'a pas eu d'impact négatif sur l'état clinique général, tel que le comportement et l'appétit, tout au long de la période d'étude. Les valeurs de densité optique obtenues lors d'épreuves immunoenzymatiques (ELISA) utilisant le lipopolysaccharide de B. abortus étaient considérablement plus élevées avec le sérum des animaux du groupe B que celui des animaux du groupe A. De plus, les niveaux des cytokines interleukine-4 (IL-4), du facteur-alpha nécrosant de tumeur (TNF-α), d'interféron-gamma (IFN-γ) étaient significativement plus élevés dans le groupe B comparativement au groupe A. Pour donner suite à l'infection-défi intra-conjonctivale avec la souche 544 de B. abortus, la sévérité de brucellose en termes d'index d'infection et de colonisation des tissus par B. abortus était significativement moindre dans le groupe B que dans le groupe A. La présente étude a permis de conclure que 3 des 5 chèvres immunisées avec les bactéries GI24 lysées étaient complètement protégées contre l'infection. Des études ultérieures sont requises pour améliorer l'efficacité protectrice offerte par les cellules lysées de B. abortus pour une application pratique chez les petits ruminants.(Traduit par Docteur Serge Messier).

Protective efficacy of a canine brucellosis vaccine candidate based on live attenuated Salmonella expressing recombinant Brucella BCSP31, Omp3b and SOD proteins in Beagles.

The aim of this study was to establish a proof-of-concept of protective efficacy of Salmonella-based B. abortus vaccine candidate in Beagles. Group A Beagles (n=10) were subcutaneously (SC) inoculated with S. Typhimurium delivery strain containing pMMP65 (vector to deliver antigens) only as vector control. Group B Beagles (n=10) were SC vaccinated with the mixture of the three Salmonella delivery strains expressing the recombinant B. abortus BCSP31, Outer membrane protein 3b (Omp3b), and superoxide dismutase (SOD) proteins, respectively. No Salmonella delivery strains were isolated from all tissues tested. Serum IgG, interleukin-4, tumor necrosis factor-alpha, and interferon-gamma concentrations were significantly higher in group B than in group A. Following intraconjunctival challenge with B. abortus 544, among 5 group B Beagles, the challenge strain was isolated from mandibular, and retropharyngeal lymph nodes of three Beagles, and no isolates were observed from all tissues of two Beagle. However, the challenge strains were detected from spleen, uterus (except two Beagles), and mandibular, prescapular, retropharyngeal, and superficial inguinal lymph nodes of all group A Beagles. These results suggest that the mixture of three S. Typhimurium delivery strains be a good vaccine candidate against brucellosis by B. abortus in dogs. Further investigations are needed to improve the protective efficacy of the Salmonella-based B. abortus vaccine candidate and explore its practical application in dogs.

Brucella abortus lysed cells using GI24 induce robust immune response and provide effective protection in Beagles.

The aim of the present study is to estimate the protective efficacy of Brucella abortus lysed cells by GI24 against brucellosis in Beagles. Group A was subcutaneously (sc) immunized with sterile phosphate-buffered saline, and group B was sc immunized with approximately 3 × 109 of the lysed cells. Brucella-LPS-specific serum IgG titers and IL-4, TNF-α and IFN-γ concentrations were investigated by enzyme linked immunosorbent assay. All dogs were intraconjunctivally challenged with B. abortus strain 544 at 6 weeks post-prime immunization. The serum IgG titers were considerably higher in group B than in group A. The levels of IL-4, TNF-α and IFN-γ in group B than in group A were significantly higher. Following challenge, no challenge strain was observed from all tissues of three dogs of group B. However, challenge strain was detected from spleen, uterus (except one Beagle) and inguinal and retropharyngeal lymph nodes of all group A Beagles. The results of this study demonstrated that sc immunization with the lysed cells induced robust antibody and cell-mediated immune responses in Beagles. The lysed cells also conferred protection against infection with B. abortus. These results suggest that sc immunization with B. abortus lysed cells by GI24 is a good vaccine candidate against brucellosis in dogs.

Vaccination of goats with a combination Salmonella vector expressing four Brucella antigens (BLS, PrpA, Omp19, and SOD) confers protection against Brucella abortus infection.

Salmonella is an intracellular pathogen with a cellular infection mechanism similar to that of Brucella, making it a suitable choice for use in an anti-Brucella immune boost system. This study explores the efficacy of a Salmonella Typhimurium delivery-based combination vaccine for four heterologous Brucella antigens (Brucella lumazine synthase, proline racemase subunit A, outer-membrane protein 19, and Cu/Zn superoxide dismutase) targeting brucellosis in goats. We inoculated the attenuated Salmonella delivery-based vaccine combination subcutaneously at two different inoculation levels; 5 × 109 colony-forming unit (CFU)/mL (Group B) and 5 × 1010 CFU/mL (Group C) and challenged the inoculations with virulent Brucella abortus at 6 weeks post-immunization. Serum immunoglobulin G titers against individual antigens in Salmonella immunized goats (Group C) were significantly higher than those of the non-immunized goats (Group A) at 3 and 6 weeks after vaccination. Upon antigenic stimulation, interferon-γ from peripheral blood mononuclear cells was significantly elevated in Groups B and C compared to that in Group A. The immunized goats had a significantly higher level of protection as demonstrated by the low bacterial loads in most tissues from the goats challenged with B. abortus. Relative real-time polymerase chain reaction results revealed that the expression of Brucella antigens was lower in spleen, kidney, and lung of immunized goats than of non-immunized animals. Also, treatment with our combination vaccine ameliorated histopathological lesions induced by the Brucella infection. Overall, the Salmonella Typhimurium delivery-based combination vaccine was effective in delivering immunogenic Brucella proteins, making it potentially useful in protecting livestock from brucellosis.

Protective efficacy by various doses of a new brucellosis vaccine candidate based on Salmonella strains expressing Brucella abortus BSCP31, Omp3b and superoxide dismutase against brucellosis in murine model.

Brucella species are important etiological agents of zoonotic diseases. Attenuated Salmonella strains expressing Brucella abortus BCSP31, Omp3b and superoxide dismutase proteins were tested as vaccine candidates in this study. In order to determine the optimal dose for intraperitoneal (IP) inoculation required to obtain effective protection against brucellosis, mice were immunized with various doses of a mixture of the three vaccine strains. Fifty BALB/c mice were divided into five equal groups (groups A-E). Group A mice were intraperitoneally inoculated with 100 µL of sterile phosphate-buffered saline. Group B, C, D and E mice were intraperitoneally immunized with approximately 1.2 × 105 colony-forming units (CFU) mL-1 of Salmonella containing pMMP65 in 100 µL and with 1.2 × 104 CFU mL-1, 1.2 × 105 CFU mL-1 and 1.2 × 106 CFU mL-1 of the mixture of the three strains in 100 µL, respectively. Serum IgG, tumor necrosis factor alpha and interferon gamma concentrations were significantly higher in group E than in groups A-D. Following challenge with B. abortus 544, the challenge strain was not detected in the spleen of any mouse from group E. Thus, IP immunization with 1.2 × 106 CFU mL-1 of the mixture of the three vaccine strains induced immune responses and provided effective protection against brucellosis in mice.