TY - JOUR
T1 - Inverse relationship between heat stable enterotoxin-b induced fluid accumulation and adherence of F4ac-positive enterotoxigenic Escherichia coli in ligated jejunal loops of F4ab/ac fimbria receptor-positive swine
AU - Erume, Joseph
AU - Wijemanne, Prageeth
AU - Berberov, Emil M.
AU - Kachman, Stephen D.
AU - Oestmann, Daniel J.
AU - Francis, David H.
AU - Moxley, Rodney A.
N1 - Funding Information:
The authors thank Doreen Bailey, Karen Hansen, Blaine Clowser and Kandy Lytle for technical assistance, and Drs. Raúl Barletta and Andrew Benson for helpful advice and comments. This study was supported by the National Research Initiative of the USDA National Research Initiative Competitive Grants Program , grant 2004-35204-14915 , and funds provided through the Hatch Act , NC-1041 Enteric Diseases of Swine and Cattle: Prevention, Control and Food Safety. The funding source had no role in the study design, collection, analysis or interpretation of data, and did not provide assistance with the writing of this manuscript.
PY - 2013/1/25
Y1 - 2013/1/25
N2 - Heat-labile enterotoxin (LT) produced by enterotoxigenic Escherichia coli (ETEC) increases bacterial adherence to porcine enterocytes in vitro and enhances small intestinal colonization in swine. Heat-stable enterotoxin-b (STb) is not known to affect colonization; however, through an induction of net fluid accumulation it might reduce bacterial adherence. The relationship between fluid accumulation and bacterial adherence in jejunal loops inoculated with ETEC strains that produce LT, STb, both, or neither toxin was studied. Ligated jejunal loops were constructed in weaned Yorkshire pigs in two independent experiments (Exp. 1, n=5, 8-week-old; Exp. 2, n=6, 6-8-week-old). Each pig was inoculated with six F4ac+ E. coli strains: (1) LT+, STb+ parent (WAM2317); (2) STb- (ΔestB) mutant (MUN297); (3) MUN297 complemented with STb (MUN298); (4) LT- STb- (ΔeltAB ΔestB) mutant (MUN300); (5) MUN300 complemented with LT (MUN301); and (6) 1836-2 (non-enterotoxigenic, wild-type). Pigs were confirmed to be K88 (F4)ab/ac receptor-positive in Exp. 2 by testing for intestinal mucin-type glycoproteins and inferred to be receptor-positive in both Exp. 1 and 2 based on histopathologic evidence of bacterial adherence. Strains that produced STb induced marked fluid accumulation with the response (ml/cm) to WAM2317 and MUN298 significantly greater than that to the other strains (P<0.0001). Conversely, bacterial adherence scores based on immunohistochemistry and CFU/g of washed mucosa were both lowest in the strains that expressed STb and highest in those that did not. For the two experiments combined, the Pearson correlation coefficient (R) between fluid volume (ml/cm) and log CFU per gram was -0.57021 (P<0.0001); R2=0.3521 (n=197). These results support the hypothesis that enterotoxin-induced fluid accumulation flushes progeny organisms into the lumen of the bowel, thereby increasing the likelihood of fecal shedding and transmission of the pathogen to new hosts.
AB - Heat-labile enterotoxin (LT) produced by enterotoxigenic Escherichia coli (ETEC) increases bacterial adherence to porcine enterocytes in vitro and enhances small intestinal colonization in swine. Heat-stable enterotoxin-b (STb) is not known to affect colonization; however, through an induction of net fluid accumulation it might reduce bacterial adherence. The relationship between fluid accumulation and bacterial adherence in jejunal loops inoculated with ETEC strains that produce LT, STb, both, or neither toxin was studied. Ligated jejunal loops were constructed in weaned Yorkshire pigs in two independent experiments (Exp. 1, n=5, 8-week-old; Exp. 2, n=6, 6-8-week-old). Each pig was inoculated with six F4ac+ E. coli strains: (1) LT+, STb+ parent (WAM2317); (2) STb- (ΔestB) mutant (MUN297); (3) MUN297 complemented with STb (MUN298); (4) LT- STb- (ΔeltAB ΔestB) mutant (MUN300); (5) MUN300 complemented with LT (MUN301); and (6) 1836-2 (non-enterotoxigenic, wild-type). Pigs were confirmed to be K88 (F4)ab/ac receptor-positive in Exp. 2 by testing for intestinal mucin-type glycoproteins and inferred to be receptor-positive in both Exp. 1 and 2 based on histopathologic evidence of bacterial adherence. Strains that produced STb induced marked fluid accumulation with the response (ml/cm) to WAM2317 and MUN298 significantly greater than that to the other strains (P<0.0001). Conversely, bacterial adherence scores based on immunohistochemistry and CFU/g of washed mucosa were both lowest in the strains that expressed STb and highest in those that did not. For the two experiments combined, the Pearson correlation coefficient (R) between fluid volume (ml/cm) and log CFU per gram was -0.57021 (P<0.0001); R2=0.3521 (n=197). These results support the hypothesis that enterotoxin-induced fluid accumulation flushes progeny organisms into the lumen of the bowel, thereby increasing the likelihood of fecal shedding and transmission of the pathogen to new hosts.
KW - Escherichia coli
KW - Heat-labile enterotoxin
KW - Heat-stable enterotoxin-b
KW - Mucin-4 gene
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U2 - 10.1016/j.vetmic.2012.07.048
DO - 10.1016/j.vetmic.2012.07.048
M3 - Article
C2 - 22901529
AN - SCOPUS:84870388973
SN - 0378-1135
VL - 161
SP - 315
EP - 324
JO - Veterinary Microbiology
JF - Veterinary Microbiology
IS - 3-4
ER -