Kinetics of Placental Infection by Different Smooth Strains in Mice.

Abortion and reproductive failures induced by are the main symptoms of animal brucellosis. Laboratory animal models are essential tools of research to study the pathogenesis before experimentation in natural hosts. To extend the existing knowledge, we studied 16M (virulent) and Rev1 (attenuated) as well as bv2 infections in pregnant mice. Here, we report new information about kinetics of infection (in spleens, blood, placentas, vaginal shedding, and foetuses), serum cytokine profiles, and histopathological features in placentas and the litter throughout mice pregnancy. Both strains showed a marked placental tropism and reduced viability of pups (mainly in 16M infections), which was preceded by an intense Th1-immune response during placental development. In contrast, bv2 displayed lower placental tropism, mild proinflammatory immune response, and scarce bacterial transmission to the litter, thus allowing foetal viability. Overall, our studies revealed three different smooth patterns of placental and foetal pathogenesis in mice, providing a useful animal model for experimental brucellosis.