Document Type

Thesis - University Access Only

Award Date

1996

Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

Alan K. Erickson

Abstract

Escherichia coli expressing the K88 fimbrial adhesin colonize the small intestine, and cause diarrhea in newborn and weaned piglets. Five phenotypes of pigs exist, distinguished by the K88 adhesin variants (K88ab, K88ac, and K88ad) that bind to their intestinal epithelial cells. These phenotypes and the K88 adhesin variant(s) that bind to them are: A-all three variants, B-K88ab and K88ac, C-K88ab and K88ad, D-K88ad, and Enone of the variants. Phenotypic differences are due to the presence of highly specific K88 fimbrial adhesin receptors on intestinal brush border membranes. Our earlier studies identified 210- and 240-kDa glycoproteins as K88ac adhesin receptors. These receptors were found in animals phenotyped as adhesive to the K88ac fimbrial adhesin and were not detectable in K88ac nonadhesive animals. The objectives of the present study were 1) to establish the distribution of the 210- and 240-kDa receptors among all 5 phenotypes, 2) to determine which K88 fimbrial adhesin variants bind to the 210- and 240-kDa receptors, and 3) to identify any novel phenotype-specific K88 adhesin receptors. Intestinal brush border membrane proteins were prepared from the five different phenotypes of pigs, separated by SDS-PAGE and transferred onto nitrocellulose membranes. These membranes were overlaid with 35S-labeled K88+ E. coli, biotinylated K88+ E. coli, or biotinylated K88 fimbrial adhesins. Bound 35S-labeled bacteria were detected by autoradiography and bound biotinylated fimbriae or E. coli were detected using horseradish peroxidase conjugated to streptavidin. We found consistent results using overlay assays with any of the three labeled forms. K88ab and K88ac fimbriae bound to the 210- and 240-kDa receptors in phenotype A and B, but not phenotype C, Dor E animals. No phenotype-specific receptors were identified that accounted for the K88ad adhesin binding. With phenotype A brush borders, blocking studies have shown that purified K88ab and K88ac fimbriae have the ability to block K88ad fimbriae binding, while purified K88ad fimbriae do not block K88ab or K88ac binding. Considered together with these blocking studies, our experimental results point to the existence of multiple K88 adhesin receptors to account for observed phenotypes. Combining the data generated from the present study and the blocking patterns, we propose a receptor model system consisting of three distinct receptors: 1) bc, the identified 210- and 240-kDa glycoprotein adhesive for the K88ab and K88ac fimbrial adhesin and expressed in phenotype A and B animals, 2) bcd, adhesive for all three fimbrial adhesins and expressed in phenotype A animals, and 3) d, specific only for the K88ad fimbrial adhesin and expressed in phenotype C and D animals.

Library of Congress Subject Headings

Escherichia coli infections in swine
Epithelial cells
Intestines -- Infections

Format

application/pdf

Publisher

South Dakota State University

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Rights Statement

In Copyright