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Infection and Immunity, September 1998, p. 4050-4055, Vol. 66, No. 9
Department of Veterinary Science, South
Dakota State University, Brookings, South Dakota 57007-1396
Received 13 February 1998/Returned for modification 31 March
1998/Accepted 4 June 1998
Three antigenic variants of the K88 fimbrial adhesin exist in
nature, K88ab, K88ac, and K88ad. Enterotoxigenic Escherichia coli (ETEC) strains that produce these fimbriae cause
life-threatening diarrhea in some but not all young pigs. The
susceptibility of pigs to these organisms has been correlated with the
adherence of bacteria to isolated enterocyte brush borders. Whether
that correlation holds for multiple K88 variants and over a broad
genetic base of pigs is unknown and was the impetus for this study. We also desired to examine the correlation of the expression of a porcine
intestinal brush border mucin-type glycoprotein (IMTGP) which binds
K88ab and K88ac with the susceptibility of piglets to K88+
ETEC. Of 31 neonatal gnotobiotic pigs inoculated with
K88ab+ or K88ac+ ETEC, 13 developed severe
diarrhea, became dehydrated, and died or became moribund.
Another pig became severely lethargic but not dehydrated. In vitro
brush border adherence analysis was not possible for 10 of the severely
ill pigs due to colonization by challenge strains. However, of the 17 pigs that did not become severely ill, 8 (47%) had brush borders that
supported the adherence of K88ab+ and K88ac+
bacteria in vitro, suggesting a poor correlation between in vitro brush
border adherence and piglet susceptibility to K88+ ETEC. By
contrast, the expression of IMTGP was highly correlated with
susceptibility to K88+ ETEC. Of the 12 pigs that produced
IMTGP, 11 developed severe diarrhea. The other pig that produced IMTGP
became lethargic but not severely diarrheic. Only 2 of 18 pigs that did
not produce IMTGP became severely diarrheic. Colonizing bacteria were
observed in histologic sections of intestines from all pigs that
expressed IMTGP except for the one that did not develop severe
diarrhea. However, colonizing bacteria were observed in histologic
sections from only one pig that did not produce IMTGP. The bacterial
concentration in the jejuna and ilea of pigs expressing IMTGP was
significantly greater (P < 0.005) than that in pigs
not expressing IMTGP. These observations suggest the IMTGP is a
biologically relevant receptor for K88ab+ and
K88ac+ E. coli or a correlate for expression
for such a receptor.
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Expression of Mucin-Type Glycoprotein K88 Receptors Strongly
Correlates with Piglet Susceptibility to K88+
Enterotoxigenic Escherichia coli, but Adhesion of This
Bacterium to Brush Borders Does Not
*
Corresponding author. Mailing address: Department of
Veterinary Science, P.O. Box 2175, South Dakota State University,
Brookings, SD 57007-1396. Phone: (605) 688-5680. Fax: (605) 688-6003. E-mail: francisd{at}mg.sdstate.edu.
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