Roles of metallic ions within an area endemic for the plague bacillus (Yersinia pestis).

There are observations that strongly suggest that the synthesis of specific factors of virulence in the plaque bacillus (Yersinia pestis) depend on the level of a specific metallic ion(s). The varied roles of metallic ions in host-plague interactions are quite similar to the structural and catalytic roles of such ions in free-living macro-and micro-organisms. The antimicrobial power of mammalian fluids is depressed by low levels of Fe and enhanced by an increase in the Fe binding capacity of a system. The bactericidal power of serum as well as endotoxin components are affected by levels of Ca and Mg. Se also plays a role in the defense mechanism of animals to certain diseases. Yet, there is sufficient uniqueness of roles of key metallic ions in many specific host systems so that the balance could be tipped in favor of either host or the plague bacillus by subtle alteration of the metallic ion environment, specifically within an area endemic for the disease.