Expression of heat-stable enterotoxin STb by adherent Escherichia coli is not sufficient to cause severe diarrhea in neonatal pigs.
The role of Escherichia coli heat-stable enterotoxin B (STb) in neonatal porcine diarrhea caused by enterotoxigenic E. coli was examined by comparing adherent isogenic strains with or without STb. The cloned STb gene (in the plasmid pRAS1) was electroporated into a nonenterotoxigenic strain (226M) which expresses the F41 adhesin. Strain 226M pRAS1 adhered and expressed STb in vivo, causing fluid secretion in ligated ileal loops in neonatal pigs. Although strain 226M pRAS1 caused very mild diarrhea in some orally inoculated neonatal pigs, the weight loss in these pigs was similar to that caused by the parental strain without STb. We conclude that STb does not significantly contribute to diarrhea caused by enterotoxigenic E. coli in neonatal pigs.
Casey
T A
TA
Enteric Diseases and Food Safety Research Unit, National Animal Disease Center, USDA Agricultural Research Service, Ames, Iowa 50010, USA. tcasey@nadc.ars.usda.gov
Herring
C J
CJ
Schneider
R A
RA
Bosworth
B T
BT
Whipp
S C
SC
D000818:Animals; D000831:Animals, Newborn; D001422:Bacterial Adhesion; D001427:Bacterial Toxins / Q000633:toxicity*; D003967:Diarrhea / Q000209:etiology*; D004768:Enterotoxins / Q000633:toxicity*; D004926:Escherichia coli / Q000472:pathogenicity*; D029968:Escherichia coli Proteins; D007082:Ileum / Q000382:microbiology; D013552:Swine
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli)