Protective effects of recombinantBrucella abortusOmp28 against infection with a virulent strain ofBrucella abortus544 in mice

Abstract

The outer membrane proteins (OMPs) of Brucella (B.) abortus have been extensively studied, but their immunogenicity and protective ability against B. abortus infection are still unclear. In the present study, B. abortus Omp28, a group 3 antigen, was amplified by PCR and cloned into a maltose fusion protein expression system. Recombinant Omp28 (rOmp28) was expressed in Escherichia coli and was then purified. Immunogenicity of rOmp28 was confirmed by Western blot analysis with Brucella-positive mouse serum. Furthermore, humoral- or cell-mediated immune responses measured by the production of IgG1 or IgG2a in rOmp28-immunized mice and the ability of rOmp28 immunization to protect against B. abortus infection were evaluated in a mouse model. In the immunogenicity analysis, the mean titers of IgG1 and IgG2a produced by rOmp28-immunized mice were 20-fold higher than those of PBS-treated mice throughout the entire experimental period. Furthermore, spleen proliferation and bacterial burden in the spleen of rOmp28-immunized mice were approximately 1.5-fold lower than those of PBS-treated mice when challenged with virulent B. abortus. These findings suggest that rOmp28 from B. abortus is a good candidate for manufacturing an effective subunit vaccine against B. abortus infection in animals.

Recent advances in Brucella abortus vaccines

“…Many of the same antigens tested as DNA vaccines have also been evaluated as potential antigens for subunit vaccines (L7/L12 ribosomal protein; P39; BLS; Omp16; Cu/Zn SOD) [ 14 , 21 , 24 , 37 , 40 ]. The outer membrane proteins (OMPs) of B. abortus , potential immunogenic antigens, have been widely explored as subunit vaccines [ 37 , 39 , 43 , 45 ]. Unlipidated recombinant Omp16 and Omp19, and recombinant Omp25 liposome encapsulated gave protection comparable to S19 in vaccinated mice following challenge [ 37 , 39 , 45 ].…”

“…Unlipidated recombinant Omp16 and Omp19, and recombinant Omp25 liposome encapsulated gave protection comparable to S19 in vaccinated mice following challenge [ 37 , 39 , 45 ]. Also, Omp28 subunit vaccine increased resistance against challenge with virulent B. abortus but at lower level than live attenuated vaccines [ 43 ].…”

Type IV secretion system of Brucella spp. and its effectors

“…lacked the characteristic virulence factors that are present in other bacteria (Fugier et al, 2007 ). However, in recent years, various virulence factors that are essential for infection, including lipopolysaccharide (LPS) (Lapaque et al, 2005 ), β-cyclic glucan (Arellano-Reynoso et al, 2005 ; Martirosyan et al, 2012 ), BvrS/BvrR (Guzman-Verri et al, 2002 ; Martín-Martín et al, 2012 ), outer membrane proteins (Omps) (Lim et al, 2012 ; Vizcaíno and Cloeckaert, 2012 ), BmaC (Posadas et al, 2012 ), MucR (Mirabella et al, 2013 ), SagA (Del Giudice et al, 2013 ), BtaE (Ruiz-Ranwez et al, 2013 ), BacA (Martín-Martín et al, 2012 ), and BetB (Lee et al, 2014 ), have been identified in Brucella VirB. T4SS is another key virulence factor that plays important roles in mediating intracellular survival and manipulating host immune response to infection.…”

Strategies for the development of an effective vaccine against Brucellosis

“…Future development of vaccines against the Brucella spe- cies is expected to integrate optimal qualities that would result into a non-replicating, efficacious vaccine that would maximize immune stimulation and cost efficiency [35]. It is our general recommendation to navigate on the possibility of genetically engineering live attenuated vaccines that could replace the currently available vaccines [43].…”