Evaluation of a DNA vaccine encoding Brucella BvrR in BALB/c mice

Abstract

Brucellosis is an important neglected zoonotic disease, and the pathogens responsible are Brucellae. In order to evaluate the immunogenicity and protective efficacy of a DNA vaccine encoding Brucella BvrR, the recombinant plasmid pCDNA-BvrR was constructed by inserting the BvrR gene fragment into a pCDNA3.0 vector. The His 6-tagged BvrR was purified with His-trap FF crude affinity chromatography and verified with an anti-histidine monoclonal antibody by western blot analysis. The specific immunoglobulin antigens and their isotypes were detected by indirect ELISA. The recombinant His 6-BvrR protein was expressed and purified by affinity chromatography. The optical density 450 value of immunoglobulin G (IgG) in the pCDNA-BvrR group was significantly increased compared with the pCDNA3.0 vector or PBS groups (P<0.05), and the pCDNA3.0 vector and PBS groups exhibited no significant difference (P>0.05). BvrR induced specific antibodies with a dominance of IgG2a over IgG1 and the T cell-proliferative response, in addition to a typical T helper-1 (Th1)-dominated immune response in mice. The splenocytes from mice of the pCDNA-BvrR group demonstrated significant proliferative activity compared with the pCDNA3.0 vector group. The present results indicated that immunization with BvrR induced a specific Th1-type immune response in mice. Subsequent to challenging with B. abortus S19, it was identified that the DNA vaccine pCDNA-BvrR induced a significant level of protection in BALB/c mice by evaluating systemic bacterial clearance. These results suggested that BvrR may be a good candidate for a DNA vaccine against brucellosis.

Screening of potential vaccine candidates against pathogenic Brucella spp. using compositive reverse vaccinology

“…A limitation in this study is the selection of hypovirulent strain B. abortus S19 as challenge strain for protection experiments [ 43 , 71 , 72 ]. B. abortus S19 was originally isolated as a virulent strain from a Jersey cow in 1923 and was found to become attenuated after being kept in the laboratory at room temperature for more than a year [ 41 , 42 ].…”

Evaluation of Brucellosis Vaccines: A Comprehensive Review

“…DNA-based vaccines contain gene sequences of pathogens, which are essential for intracellular survival of Brucella spp. The immunogenicity and efficacy of these virulence genes used in DNA vaccines have been demonstrated in animal studies, including the two-component BvrR/BvrS system ( 119 ), Cu-Zn superoxide dismutase (SOD) ( 126 , 140 ), ribosomal L7/L12 or Brucella lumazine synthase (BLS) ( 139 , 141 ), B. melitensis omp31 and omp25 genes ( 125 , 142 ), antigenic surface protein (BCSP31) gene ( 120 ), SP41 ( 143 ), and ribosomal protein L9 (rL9) ( 122 ). According to the studies that have been done, DNA vaccines may have the ability to resolve the disadvantages of other brucellosis vaccines ( 119 , 120 , 144 ).…”

“…The immunogenicity and efficacy of these virulence genes used in DNA vaccines have been demonstrated in animal studies, including the two-component BvrR/BvrS system ( 119 ), Cu-Zn superoxide dismutase (SOD) ( 126 , 140 ), ribosomal L7/L12 or Brucella lumazine synthase (BLS) ( 139 , 141 ), B. melitensis omp31 and omp25 genes ( 125 , 142 ), antigenic surface protein (BCSP31) gene ( 120 ), SP41 ( 143 ), and ribosomal protein L9 (rL9) ( 122 ). According to the studies that have been done, DNA vaccines may have the ability to resolve the disadvantages of other brucellosis vaccines ( 119 , 120 , 144 ). In most studies, animals vaccinated with different types of DNA vaccines have shown full protection against virulent strains (e.g., B. abortus S19, B. abortus 2308, B. melitensis 16M , and B. melitensis Rev1 ) ( 120 , 143 ).…”

Immune Response to Mucosal Brucella Infection

“…In animal models it has been observed that T4SS is necessary for the onset of the infection (102). Recently it has been published that BvrR is a good candidate for a DNA vaccine in the murine brucellosis model, but many studies are missing (103).…”