Abstract
Protective efficiency of a combination of four recombinant Brucella abortus (B. abortus) proteins, namely outer membrane protein (Omp) 16, Omp19, Omp28, and 50S ribosomal protein L7/L12 was evaluated as a combined subunit vaccine (CSV) against B. abortus infection in RAW 264.7 cell line and murine model. The immunoreactivity of these four recombinant proteins as well as pCold-TF vector reacted with Brucella-positive serum individually, but not with Brucella-negative serum by immunoblotting assay. CSV-treated RAW 264.7 cells significantly induced production of IFN-γ and IL-12 while decreased IL-10 production at the late stage of infection compared to PBS-treated control cells. In addition, the enhancement of nitric oxide production together with cytokines secretion profile in CSV-treated cells proved that CSV notably activated bactericidal mechanisms in macrophages. Consistently, mice immunized with CSV strongly elicited production of pro-inflammatory cytokines TNF-α, IL-6 and MCP-1 compared to PBS control group. Moreover, the concentration of IFN-γ was >IL-10 and titers of IgG2a were also heightened compared to IgG1 in CSV-immunized mice which suggest that CSV induced predominantly T helper 1 T cell. These results suggest that the CSV used in the present study is a potential candidate as a preventive therapy against brucellosis.
Highlights
Brucellosis remains an extremely common zoonotic disease worldwide caused by Brucella species that are designated as category B of potential bioterrorism agents
The results showed that these proteins reacted with Brucella-positive mouse serum and even with pCold-TF
At the early stage of infection (4 h post infection), LPS-treated cells strongly produced 1.21-fold increase in IFN-γ and 4.51fold increase in IL-12 but 2.27-fold decrease in IL-10, whereas no difference was observed in combined subunit vaccine (CSV)-treated cells compared to phosphate buffered saline (PBS)-treated cells
Summary
Brucellosis remains an extremely common zoonotic disease worldwide caused by Brucella species that are designated as category B of potential bioterrorism agents This potential is due to the various biological and pathogenic characteristics of Brucella species including being infectious via the aerosol route, being notoriously debilitating disease, having no safe and effective available vaccine for humans as well as requiring prolonged antibiotic treatment and having relapse rates. There are numerous advances in immunology, genomics, proteomics, biochemistry as well as recombinant technology that have been utilized in the development of subunit vaccines through recombinant proteins [4] This kind of vaccine is able to reduce drawbacks of live attenuated vaccines including reversion to virulence, abortion in pregnant animals and infection to humans [5]. In this study, we evaluated the ability of a combination of four B. abortus recombinant proteins L7/L12, Omp, Omp, Omp as a CSV to induce immune response against B. abortus infection in RAW 264.7 cell line and BALB/c mouse models
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