Specific DNA Fragments Coding for ST1 and LT1 Toxins, and K88 (F4) Adhesin in Enterotoxigenic Escherichia coli

Abstract

Ten porcine strains of enterotoxigenic Escherichja coli possessing the K88 (F4) adhesion fimbriae, were selected for study of enterotoxin-and fimbriae-encoding plasmids. Plasmid DNA, separated according to size by gel electrophoresis was transferred to nylon membranes by Southern blotting, and hybridized with enzyme-labelled oligonucleotide probes for STI and LTI enterotoxins, and a '*P-labelled probe for the F4 fimbriae. Plasmids possessing the enterotoxin genes ranged from 50 MDa to 78 MDa in size. The ST1 genes were located on a common 8-MDa EcoRl restriction endonuclease fragment, while the LTI genes were located on a 4.5-MDa EcoRl fragment from the different plasmids. Plasmids with the F4 genes ranged from 50 MDa to 118 MDa in size, but the F4 encoding genes were located on a common 3-MDa Hind111 restriction endonuclease fragment. ST1 and LTI genes were found on the same plasmid in only one strain, LT1 and F4 genes on the same plasmids in 5 strains, while no plasmid contained genes for both STI and F4.

Prevalence of enterotoxigenic Escherichia coli virulence genes from scouring piglets in Zimbabwe

“…The most significant contributors to piglet ETEC diarrhea were LT and STb. The STb toxin gene has been primarily found in association with ETEC strains from scouring piglets (Erume et al 2008) and genes for LT and STb are usually found on the same plasmid (Wasteson and Olsvik 1991). Interestingly, a few Stx-2e toxin genes were present among E. coli isolates from diarrheic piglets without any clinical signs of edema disease.…”

F4 Fimbriae Expressed by Porcine Enterotoxigenic <i>Escherichia coli</i>, an Example of an Eccentric Fimbrial System?

“…F4 synthesis is controlled by a non-conjugative plasmid [Shipley et al, 1978] with a ranging molecular weight of 50-177 MDa [Shipley et al, 1978;Wasteson and Olsvik, 1991;Bertin, 1992;de Graaf, 1990;Mainil et al, 1998]. Therefore, F4 expression by E. coli can be spontaneously lost [Ørskov and Ørskov, 1966].…”

Virulence Genes and Antimicrobial Susceptibilities of Hemolytic and Nonhemolytic Escherichia coli Isolated from Post-Weaning Piglets in Central Thailand

“…According to their possession of distinct virulence genes, pathogenic E. coli strains are classified into several major categories, i.e., enterotoxigenic (ETEC), enteropathogenic (EPEC), enterohemorrhagic/shiga toxin producing E. coli (EHEC/STEC), enteroinvasive (EIEC), enteroaggregative (EAggEC) and the diffusely-adherent group (DAEC) [15,31]. In piglets, ETEC predominantly cause neonatal and postweaning diarrhea by producing heat-labile (LTh) and heat-stable (ST) enterotoxins [38,41]. LTh toxin shares 82% amino acid homology with cholera toxin, which leads to activation of adenyl cyclase and chloride ion efflux [19].…”