Bacillus anthracis Edema and Lethal Toxin Have Different Hemodynamic Effects but Function Together to Worsen Shock and Outcome in a Rat Model.
J Infect Dis. 2007 Feb 15;195(4):572-80. Epub 2007 Jan 3.
Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD, 20892, USA. email@example.com.
Introduction. To better define the contribution of edema toxins (ETx) and lethal toxins (LeTx) to shock with Bacillus anthracis, recombinant preparations of each were investigated alone or together in rats.
Methods and results. Lethal dose ranges (0%-100% lethality) of ETx (200-800 mu g/kg as a 24-h infusion) were higher than those of LeTx (12.5-200 mu g/kg) (P<.0001). However, compared with LeTx, similarly lethal ETx doses produced earlier and greater reductions in mean blood pressure (MBP) and increased, rather than decreased, heart rate (HR) (P<.05 for all). Combining either similar weight or lethal doses of ETx and LeTx increased the hazard ratio for death (log +/- standard error) similar to the sum calculated with the toxin's effects alone (2.6+/-1.1 observed vs. 2.9+/-1.0 calculated for similar weight and 3.1+/-1.0 vs. 3.9+/-1.5 for similar lethal doses; P=.5 for both). Early
and late during infusion, ETx and LeTx together also altered MBP and HR in patterns consistent with the sum of their individual effects.
Conclusions. ETx was ~10 times less lethal than LeTx but produced greater hypotension and added to the latter's harmful effects. These findings suggest that it may be appropriate for antitoxin therapies for B. anthracis to target both ETx and LeTx.
University of Chicago Press
Critical Care Medicine Department, National Institutes of Health, Building 10, Room 2C145, Bethesda, MD 20892. firstname.lastname@example.org.
Recent research regarding the structure and function of Bacillus anthracis lethal (LeTx) and edema (ETx) toxins provides growing insights into the pathophysiology and treatment of shock with this lethal bacteria. These are both binary-type toxins composed of protective antigen necessary for their cellular uptake and either lethal or edema factors, the toxigenic moieties.