Evaluation of the immunogenicity and the protective efficacy in mice of a DNA vaccine encoding SP41 from Brucella melitensis

Abstract

Introduction: Brucella melitensis is a facultative intracellular Gram-negative bacterial pathogen that may enter the host via ingestion or inhalation, or through conjunctiva or skin abrasions. Some Brucella spp surface proteins (SPs) play an important role in bacterial adhesion and invasion and thus represent targets for the host immune system. Brucella spp surface protein with apparent molecular mass of 41 kDa interacts selectively with HeLa cells. Methodology: To evaluate the role of SP41 (41 kDa) as a DNA vaccine against Brucella spp., pCISP41, a plasmid construct for protein expression in mammalian cells, was established. Exogenous SP41 was detected in pCISP41-transfected Vero cell line by immune blotting using specific polyclonal antibody. The protective role of pCISP41 against B. melitensis 16M in mice was evaluated by measuring B and T cell responses in comparison to those achieved with attenuated B. melitensis Rev. 1 vaccine. Results: BALB/c mice injected with pCISP41 were able to develop SP41-specific serum immunoglobulin G (IgG) antibodies. In addition, splenocytes from DNA-SP41-vaccinated mice elicited a T-cell-proliferative response and also induced gamma interferon (IFN-γ) production, but not interleukin-5 (IL-5), suggesting the induction of a T-helper-1-dominated immune response. Vaccination with attenuated B. melitensis Rev.1 strain induced better protection levels than DNA vaccination with SP41 against B. melitensis 16M in mice. Conclusion: Such responses play an important role against intracellular infecting agents such as Brucella spp. Altogether, our data suggest that SP41 may represent a promising candidate for DNA vaccination against brucellosis, but more investigation to increase its protective efficacy should be done.

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 ).…”

“…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 ).…”

“…Intramuscular (i.m.) administration of DNA-based vaccine has been shown to induce a protective immune response as similar as Rev1 in different animal model studies ( 125 , 143 , 145 , 146 ). Jain et al demonstrated that the electroporation (EP) approach induced further protective responses than the i.m.…”

“…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). (120,143). Intramuscular (i.m.)…”

“…route (122). A combination of several suitable antigens, such as L7/L12, BCSP31, SOD, P39, and omp16, could be used to make a "divalent or poly-antigenic DNA vaccine, " which has been reported to be effective due to more antigenic components, induction of a wide range of humoral and cellular immune responses, and simulation of the most similar status to Brucella infection (78,126,143,(147)(148)(149).…”