Brucella spp. are intracellular facultative gram-negative bacteria which are pathogenic for many species of mammals, causing brucellosis, a worldwide spread zoonosis. Therefore the search for more efficient alternatives of control, as the development of new potential immunogens is necessary. In this study, we knockouted virB10 from Brucella abortus S2308 strain, generating a mutant strain probably incapable to produce the corresponding native protein. The gene virB10 is part of an operon that codifies for type IV secretion system, which is essential for the intracellular survival and multiplication of the bacteria in host cells. The knockout was carried through by the construction of the suicidal plasmid pBlue: virB10: kan and eletroporation in eletrocompetent cells of B. abortus S2308, leading to the exchange of the wild gene for the interrupted gene, containing the gene of resistance to kanamycin, for double homologous recombination. BALB/c mice were inoculated with S19, RB-51, ΔvirB10 strains of B. abortus and S2308 wild strain; the results demonstrated that the BALB/c mice inoculated with S19 and BALB/c mice inoculated with S2308 presented faster fall of trend line, when compared with the too much groups, for bacterial recovery (BR) and esplenic weight (EW) respectively. The groups that received ΔvirB10 S2308 B. abortus and RB-51 demonstrated similar behavior for both the characteristics. In the sixth week postinoculation, the results for BR (log UFC ± standart deviations) and EW (esplenic weight ± standart deviations), respectively, showed: groups inoculated with strains S2308 (4,44±1,97 and 0,44±0,11), S19 (1,83±2,54 and 0,31±0,04), RB-51 (0,00±0,00 and 0,20±0,01) and ΔvirB10 S2308 (1,43±1,25 and 0,19±0,03). Considered the bacterial clearance, all the groups differed statistical from the group that received S2308 (p<0,0001), the group inoculated with ΔvirB10 S2308 B. abortus was similar to the S19 group (p=0,4302) and different of group RB-51 (p=0,0063). The evaluation of the persistence of the strains showed that virB10 is essential for the maintenance of the virulence. These results support other studies concerning the immunogenic potential of this mutant strain.
Brucella abortus; virB10 gene; knockout; virulence
