Infection and Immunity, January 2001, p. 315-324, Vol. 69, No. 1
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.1.315-324.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Biology Department, Reed College, Portland, Oregon 972021; Center for Vaccine Development,3 Department of Microbiology & Immunology,4 and Departments of Medicine and Pediatrics,5 University of Maryland School of Medicine, Baltimore, Maryland 21201; and Department of Public Health, Department of Cell Biology, CINVESTAV-IPN, 07000 Mexico DF, Mexico2
Received 13 September 2000/Accepted 28 September 2000
At least five proteins are secreted extracellularly by enteropathogenic Escherichia coli (EPEC), a leading cause of infant diarrhea in developing countries. However only one, EspC, is known to be secreted independently of the type III secretion apparatus encoded by genes located within the 35.6-kb locus of enterocyte effacement pathogenicity island. EspC is a member of the autotransporter family of proteins, and the secreted portion of the molecule is 110 kDa. Here we determine that the espC gene is located within a second EPEC pathogenicity island at 60 min on the chromosome of E. coli. We also show that EspC is an enterotoxin, indicated by rises in short-circuit current and potential difference in rat jejunal tissue mounted in Ussing chambers. In addition, preincubation with antiserum against the homologous Pet enterotoxin of enteroaggregative E. coli eliminated EspC enterotoxin activity. Like the EAF plasmid, the espC pathogenicity island was found only in a subset of EPEC, suggesting that EspC may play a role as an accessory virulence factor in some but not all EPEC strains.
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