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Relationship between heat-labile enterotoxin secretion capacity and virulence in wild type porcine-origin enterotoxigenic Escherichia coli strains.

Wijemanne P, Xing J, Berberov EM, Marx DB, Francis DH, Moxley RA - PLoS ONE (2015)

Bottom Line: Maximum Likelihood phylogenetic trees constructed using T2SS genes gspC, gspD, gspE and homologs showed that strains 2534-86 and 3030-2 clustered together in the same clade with other porcine-origin ETEC strains in the database, UMNK88 and UMN18.Protein modeling of the ATPase gene (gspE) further revealed a direct relationship between the predicted ATP-binding capacities and LT secretion levels as follows: H10407, -8.8 kcal/mol and 199 ng/ml; 3030-2, -8.6 kcal/mol and 133 ng/ml; and 2534-86, -8.5 kcal/mol and 80 ng/ml.This study demonstrated a direct relationship between predicted ATP-binding capacity of GspE and LT secretion, and between the latter and virulence.

View Article: PubMed Central - PubMed

Affiliation: School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America.

ABSTRACT
Heat-labile enterotoxin (LT) is an important virulence factor secreted by some strains of enterotoxigenic Escherichia coli (ETEC). The prototypic human-origin strain H10407 secretes LT via a type II secretion system (T2SS). We sought to determine the relationship between the capacity to secrete LT and virulence in porcine-origin wild type (WT) ETEC strains. Sixteen WT ETEC strains isolated from cases of severe diarrheal disease were analyzed by GM1ganglioside enzyme-linked immunosorbent assay to measure LT concentrations in culture supernatants. All strains had detectable LT in supernatants by 2 h of culture and 1 strain, which was particularly virulent in gnotobiotic piglets (3030-2), had the highest LT secretion level all porcine-origin WT strains tested (P<0.05). The level of LT secretion (concentration in supernatants at 6-h culture) explained 92% of the variation in time-to-a-moribund-condition (R2 = 0.92, P<0.0001) in gnotobiotic piglets inoculated with either strain 3030-2, or an ETEC strain of lesser virulence (2534-86), or a non-enterotoxigenic WT strain (G58-1). All 16 porcine ETEC strains were positive by PCR analysis for the T2SS genes, gspD and gspK, and bioinformatic analysis of 4 porcine-origin strains for which complete genomic sequences were available revealed a T2SS with a high degree of homology to that of H10407. Maximum Likelihood phylogenetic trees constructed using T2SS genes gspC, gspD, gspE and homologs showed that strains 2534-86 and 3030-2 clustered together in the same clade with other porcine-origin ETEC strains in the database, UMNK88 and UMN18. Protein modeling of the ATPase gene (gspE) further revealed a direct relationship between the predicted ATP-binding capacities and LT secretion levels as follows: H10407, -8.8 kcal/mol and 199 ng/ml; 3030-2, -8.6 kcal/mol and 133 ng/ml; and 2534-86, -8.5 kcal/mol and 80 ng/ml. This study demonstrated a direct relationship between predicted ATP-binding capacity of GspE and LT secretion, and between the latter and virulence.

No MeSH data available.


Related in: MedlinePlus

Higher (100X objective) magnification photomicrograph of jejunum shown in Fig. 5 with detail of necrotic and intact villi.The lamina propria of a necrotic villus is hemorrhagic (H), and contains numerous cells with pyknotic nuclei (P), indicating coagulation necrosis. The epithelium overlying this villus is absent, due to necrosis and sloughing of epithelial cells into the intestinal lumen. The exposed basal lamina of the necrotic villus is colonized with enterotoxigenic E. coli (vertical arrow), with bacteria having penetrated into the lamina propria with access to the microcirculation. The villi above and to the right of the necrotic villus have ETEC bacteria (horizontal arrow) colonizing the apical surfaces of absorptive epithelial cells. Many of these epithelial cells are in the process of sloughing as evidenced by the presence of clefts (C) between their basolateral surfaces and the underlying basal lamina. Photomicrograph was taken of 4 μm-thick section of 10% neutral-buffered formalin-fixed, paraffin-embedded jejunal tissue stained with hematoxylin and eosin. Bar = 20 μm.
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pone.0117663.g006: Higher (100X objective) magnification photomicrograph of jejunum shown in Fig. 5 with detail of necrotic and intact villi.The lamina propria of a necrotic villus is hemorrhagic (H), and contains numerous cells with pyknotic nuclei (P), indicating coagulation necrosis. The epithelium overlying this villus is absent, due to necrosis and sloughing of epithelial cells into the intestinal lumen. The exposed basal lamina of the necrotic villus is colonized with enterotoxigenic E. coli (vertical arrow), with bacteria having penetrated into the lamina propria with access to the microcirculation. The villi above and to the right of the necrotic villus have ETEC bacteria (horizontal arrow) colonizing the apical surfaces of absorptive epithelial cells. Many of these epithelial cells are in the process of sloughing as evidenced by the presence of clefts (C) between their basolateral surfaces and the underlying basal lamina. Photomicrograph was taken of 4 μm-thick section of 10% neutral-buffered formalin-fixed, paraffin-embedded jejunal tissue stained with hematoxylin and eosin. Bar = 20 μm.


Relationship between heat-labile enterotoxin secretion capacity and virulence in wild type porcine-origin enterotoxigenic Escherichia coli strains.

Wijemanne P, Xing J, Berberov EM, Marx DB, Francis DH, Moxley RA - PLoS ONE (2015)

Higher (100X objective) magnification photomicrograph of jejunum shown in Fig. 5 with detail of necrotic and intact villi.The lamina propria of a necrotic villus is hemorrhagic (H), and contains numerous cells with pyknotic nuclei (P), indicating coagulation necrosis. The epithelium overlying this villus is absent, due to necrosis and sloughing of epithelial cells into the intestinal lumen. The exposed basal lamina of the necrotic villus is colonized with enterotoxigenic E. coli (vertical arrow), with bacteria having penetrated into the lamina propria with access to the microcirculation. The villi above and to the right of the necrotic villus have ETEC bacteria (horizontal arrow) colonizing the apical surfaces of absorptive epithelial cells. Many of these epithelial cells are in the process of sloughing as evidenced by the presence of clefts (C) between their basolateral surfaces and the underlying basal lamina. Photomicrograph was taken of 4 μm-thick section of 10% neutral-buffered formalin-fixed, paraffin-embedded jejunal tissue stained with hematoxylin and eosin. Bar = 20 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358887&req=5

pone.0117663.g006: Higher (100X objective) magnification photomicrograph of jejunum shown in Fig. 5 with detail of necrotic and intact villi.The lamina propria of a necrotic villus is hemorrhagic (H), and contains numerous cells with pyknotic nuclei (P), indicating coagulation necrosis. The epithelium overlying this villus is absent, due to necrosis and sloughing of epithelial cells into the intestinal lumen. The exposed basal lamina of the necrotic villus is colonized with enterotoxigenic E. coli (vertical arrow), with bacteria having penetrated into the lamina propria with access to the microcirculation. The villi above and to the right of the necrotic villus have ETEC bacteria (horizontal arrow) colonizing the apical surfaces of absorptive epithelial cells. Many of these epithelial cells are in the process of sloughing as evidenced by the presence of clefts (C) between their basolateral surfaces and the underlying basal lamina. Photomicrograph was taken of 4 μm-thick section of 10% neutral-buffered formalin-fixed, paraffin-embedded jejunal tissue stained with hematoxylin and eosin. Bar = 20 μm.
Bottom Line: Maximum Likelihood phylogenetic trees constructed using T2SS genes gspC, gspD, gspE and homologs showed that strains 2534-86 and 3030-2 clustered together in the same clade with other porcine-origin ETEC strains in the database, UMNK88 and UMN18.Protein modeling of the ATPase gene (gspE) further revealed a direct relationship between the predicted ATP-binding capacities and LT secretion levels as follows: H10407, -8.8 kcal/mol and 199 ng/ml; 3030-2, -8.6 kcal/mol and 133 ng/ml; and 2534-86, -8.5 kcal/mol and 80 ng/ml.This study demonstrated a direct relationship between predicted ATP-binding capacity of GspE and LT secretion, and between the latter and virulence.

View Article: PubMed Central - PubMed

Affiliation: School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America.

ABSTRACT
Heat-labile enterotoxin (LT) is an important virulence factor secreted by some strains of enterotoxigenic Escherichia coli (ETEC). The prototypic human-origin strain H10407 secretes LT via a type II secretion system (T2SS). We sought to determine the relationship between the capacity to secrete LT and virulence in porcine-origin wild type (WT) ETEC strains. Sixteen WT ETEC strains isolated from cases of severe diarrheal disease were analyzed by GM1ganglioside enzyme-linked immunosorbent assay to measure LT concentrations in culture supernatants. All strains had detectable LT in supernatants by 2 h of culture and 1 strain, which was particularly virulent in gnotobiotic piglets (3030-2), had the highest LT secretion level all porcine-origin WT strains tested (P<0.05). The level of LT secretion (concentration in supernatants at 6-h culture) explained 92% of the variation in time-to-a-moribund-condition (R2 = 0.92, P<0.0001) in gnotobiotic piglets inoculated with either strain 3030-2, or an ETEC strain of lesser virulence (2534-86), or a non-enterotoxigenic WT strain (G58-1). All 16 porcine ETEC strains were positive by PCR analysis for the T2SS genes, gspD and gspK, and bioinformatic analysis of 4 porcine-origin strains for which complete genomic sequences were available revealed a T2SS with a high degree of homology to that of H10407. Maximum Likelihood phylogenetic trees constructed using T2SS genes gspC, gspD, gspE and homologs showed that strains 2534-86 and 3030-2 clustered together in the same clade with other porcine-origin ETEC strains in the database, UMNK88 and UMN18. Protein modeling of the ATPase gene (gspE) further revealed a direct relationship between the predicted ATP-binding capacities and LT secretion levels as follows: H10407, -8.8 kcal/mol and 199 ng/ml; 3030-2, -8.6 kcal/mol and 133 ng/ml; and 2534-86, -8.5 kcal/mol and 80 ng/ml. This study demonstrated a direct relationship between predicted ATP-binding capacity of GspE and LT secretion, and between the latter and virulence.

No MeSH data available.


Related in: MedlinePlus