MIP and abortion: A recent study evaluating two recombinant antigens, macrophage infectivity potentiator (MIP) and chlamydial protease-like activity factor (CPAF), in pregnant sheep found that the separate administration of these antigens did not confer any protection following challenge, while a combination of both antigens resulted in a 50% reduction in abortion rate when compared to the unvaccinated challenge control group [27], suggesting that other antigens are required for protective efficacy.