Protection of pregnant mice against placental and splenic infection by three strains of Chlamydophila abortus with a live 1B vaccine.

The efficacy of a live 1B vaccine against three strains of Chlamydophila abortus, AB16, LLG and POS, was assessed in pregnant mice in terms of the reduction in the levels of infection recorded in their placentas, fetuses and spleens. The vaccine was more effective against the AB16 strain than against the LLG and POS strains, suggesting that there are antigenic differences between the three strains.