The Spore as an Infectious Agent: Anthrax Disease as a Paradigm
James M. Vergis, Christy L. Ventura, Louise D. Teel and Alison D. O'Brien
from: Bacterial Spores: Current Research and Applications (Edited by: Ernesto Abel-Santos). Caister Academic Press, U.K. (2012)
The zoonotic disease anthrax is caused by the inhalation, ingestion, or cutaneous inoculation of Bacillus anthracis spores into a susceptible host. While inhalational anthrax is rare in humans, the 2001 distribution of B. anthracis spores through the U.S. mail led to an acceleration of research on disease progression in animal models, vaccines and therapeutics. After inoculation, spores are rapidly phagocytosed by macrophages and dendritic cells where they germinate into vegetative bacilli that produce toxins and capsule, both of which facilitate dissemination in the host. The vegetative bacilli are susceptible to antibiotics, the only licensed post-exposure treatment against B. anthracis. Despite the fact that the spore is the infectious particle, the currently approved vaccines for humans in the US and UK are derived from the vegetative culture filtrate of a toxigenic, nonencapsulated B. anthracis strain; the vaccines primarily contain Protective Antigen (PA). Here we describe the role of the spore in anthrax disease progression. In addition, we discuss PA-based vaccines and therapeutics, as well as historical applications of spore-based vaccines. Finally, we present current research focused on spore antigen vaccines and germination modulators read more ...