Brucellosis is one of the most serious
zoonoses all over the world, with B. melitensis, B. abortus and B. suis being the most pathogenic species for humans. Vaccination of domesticated livestock still represents the most efficient way to prevent human
infection. However, the available Brucella
vaccines retain an important residual virulence and induce
antibodies interfering with surveillance programs. Moreover, each
vaccine shows different protective effects versus different Brucella species and different animal hosts. Nowadays, while B. melitensis and B. suis
infections in cattle are emerging as a significant problem, there are no available
vaccines to overcome such issue. B. melitensis strain
B115, a natural, attenuated rough strain in our previous studies proved to be highly protective against B. melitensis and B. ovis
infections in mice, without inducing interfering
antibodies. In this study, we tested the efficiency of
B115 as
vaccine against B. abortus and B. suis. Vaccination of mice with 10(8) CFU/mouse of B. melitensis
B115 conferred a satisfactory protection against B. abortus 2308. On the contrary, mice vaccinated once with 10(8) or 10(9) CFU/mouse of
B115 were weakly protected against B. suis
infection. Conversely, when mice were vaccinated twice with 10(9) CFU
B115/mouse, the protective activity significantly increased. Unlike its rough phenotype,
B115 showed an adequate persistence in mice accompanied to a solid humoral and cell-mediated immunity. All together, these findings suggest the potential usefulness of
B115 to control
brucellosis in animal hosts due to heterologous challenges.