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Genomic and Phenomic Study of Mammary Pathogenic Escherichia coli.

Blum SE, Heller ED, Sela S, Elad D, Edery N, Leitner G - PLoS ONE (2015)

Bottom Line: Analysis of whole genome sequences and predicted proteomes revealed high similarity among MPEC, whereas MPEC significantly differed from the non-mammary pathogenic strain K71, and from E. coli genomes from other pathotypes.Functional features identified in MPEC genomes and lacking in the non-mammary pathogenic strain were associated with synthesis of lipopolysaccharide and other membrane antigens, ferric-dicitrate iron acquisition and sugars metabolism.Among phenotypes unique to MPEC compared to the non-mammary pathogenic strain were uric acid and D-serine metabolism.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot, Israel; National Mastitis Reference Center, Department of Bacteriology, Kimron Veterinary Institute, Bet Dagan, Israel; Department of Bacteriology, Kimron Veterinary Institute, Bet Dagan, Israel.

ABSTRACT
Escherichia coli is a major etiological agent of intra-mammary infections (IMI) in cows, leading to acute mastitis and causing great economic losses in dairy production worldwide. Particular strains cause persistent IMI, leading to recurrent mastitis. Virulence factors of mammary pathogenic E. coli (MPEC) involved pathogenesis of mastitis as well as those differentiating strains causing acute or persistent mastitis are largely unknown. This study aimed to identify virulence markers in MPEC through whole genome and phenome comparative analysis. MPEC strains causing acute (VL2874 and P4) or persistent (VL2732) mastitis were compared to an environmental strain (K71) and to the genomes of strains representing different E. coli pathotypes. Intra-mammary challenge in mice confirmed experimentally that the strains studied here have different pathogenic potential, and that the environmental strain K71 is non-pathogenic in the mammary gland. Analysis of whole genome sequences and predicted proteomes revealed high similarity among MPEC, whereas MPEC significantly differed from the non-mammary pathogenic strain K71, and from E. coli genomes from other pathotypes. Functional features identified in MPEC genomes and lacking in the non-mammary pathogenic strain were associated with synthesis of lipopolysaccharide and other membrane antigens, ferric-dicitrate iron acquisition and sugars metabolism. Features associated with cytotoxicity or intra-cellular survival were found specifically in the genomes of strains from severe and acute (VL2874) or persistent (VL2732) mastitis, respectively. MPEC genomes were relatively similar to strain K-12, which was subsequently shown here to be possibly pathogenic in the mammary gland. Phenome analysis showed that the persistent MPEC was the most versatile in terms of nutrients metabolized and acute MPEC the least. Among phenotypes unique to MPEC compared to the non-mammary pathogenic strain were uric acid and D-serine metabolism. This study reveals virulence factors and phenotypic characteristics of MPEC that may play a role in pathogenesis of E. coli mastitis.

No MeSH data available.


Related in: MedlinePlus

Histological examination of mice mammary glands.A, non-pyrogenic phosphate-buffered saline (negative control), 1 DPC, no histological changes (x10); B, strain K71, 1 DPC, focal light inter-alveolar infiltrate with no signs of inflammation of the gland (x4); C, strain P4, 1 DPC, focal intra-alveolar PMN infiltration (x4); D, strain P4, 2 DPC, recovery of the gland and no inflammatory infiltrate or significant damage (x10); E, strain VL2874, 1 DPC, extensive intra-alveolar and ductal PMN infiltration (x4); F, strain VL2874, 2 DPC, partially destructed non-lactating alveoli, protein deposit and necrosis (x10); G, strain VL2732, 1 DPC, diffuse inter and intra-alveolar PMN infiltration (x10); H, strain VL2732, 2 DPC, inter-alveolar inflammatory infiltrate, necrosis, hyperemia and loss of alveoli architecture (x10); I, strain VL2732, 5 DPC, degenerative PMN, diffuse necrosis, hemorrhage, protein deposit and extensive loss of alveoli architecture (x10); J-K, strain K-12 MG1655, 1 DPC, diffuse intra-alveolar PMN infiltration without alterations to the gland structure and numerous lactating alveoli (x4-x20); L, representative picture of intra-alveolar PMN infiltration (x20). Eosine-hematoxylin stain.
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pone.0136387.g001: Histological examination of mice mammary glands.A, non-pyrogenic phosphate-buffered saline (negative control), 1 DPC, no histological changes (x10); B, strain K71, 1 DPC, focal light inter-alveolar infiltrate with no signs of inflammation of the gland (x4); C, strain P4, 1 DPC, focal intra-alveolar PMN infiltration (x4); D, strain P4, 2 DPC, recovery of the gland and no inflammatory infiltrate or significant damage (x10); E, strain VL2874, 1 DPC, extensive intra-alveolar and ductal PMN infiltration (x4); F, strain VL2874, 2 DPC, partially destructed non-lactating alveoli, protein deposit and necrosis (x10); G, strain VL2732, 1 DPC, diffuse inter and intra-alveolar PMN infiltration (x10); H, strain VL2732, 2 DPC, inter-alveolar inflammatory infiltrate, necrosis, hyperemia and loss of alveoli architecture (x10); I, strain VL2732, 5 DPC, degenerative PMN, diffuse necrosis, hemorrhage, protein deposit and extensive loss of alveoli architecture (x10); J-K, strain K-12 MG1655, 1 DPC, diffuse intra-alveolar PMN infiltration without alterations to the gland structure and numerous lactating alveoli (x4-x20); L, representative picture of intra-alveolar PMN infiltration (x20). Eosine-hematoxylin stain.

Mentions: Pathogenicity in the mammary gland was studied in a murine model of intra-mammary infection. The murine model of intra-mammary infection has been widely used for the research of pathogenesis, immune response, treatment and prevention of mastitis, but only in a few instances it was used for comparison between the pathogenicity of different strains of the same pathogen species [47]. As expected, all three strains isolated from mastitis elicited clear intra-mammary inflammation in mice. Moreover, different patterns of inflammation were observed with the distinct MPEC strains on gross and histopathological examination of challenged mammary glands, and an analogy could be made between these patterns and the disease presentation observed in the mammary glands of cows originally infected by the strains studied here. For instance, strain VL2874 caused fast degeneration of mice glands within 1 DPC with extensive tissue destruction, whereas strain VL2732 caused a prolonged inflammation up to 5 DPC with a granuloma-like reaction, indicative of a chronic reaction. Comparably, the cow affected by VL2874 showed per-acute mastitis, no recovery of the affected gland to lactation, and extensive regions of gland tissue degeneration were observed histologically after culling. In contrast, VL2732 caused persistent, chronic infection in the cow mammary gland from which it was originally isolated. Compared to the two previous strains, strain P4 caused a milder inflammation in murine mammary glands. Results are summarized in Table 2 and representative histopathological images are presented in Fig 1. In accord to previous work [48], the murine model was shown to be applicable for the purpose of MPEC inter-strain comparisons. Finally, no signs of mastitis whatsoever were observed in mice challenged with strain K71, confirming that strain K71 was suitable for comparison to MPEC for the identification of potential mastitis pathogenicity-related traits.


Genomic and Phenomic Study of Mammary Pathogenic Escherichia coli.

Blum SE, Heller ED, Sela S, Elad D, Edery N, Leitner G - PLoS ONE (2015)

Histological examination of mice mammary glands.A, non-pyrogenic phosphate-buffered saline (negative control), 1 DPC, no histological changes (x10); B, strain K71, 1 DPC, focal light inter-alveolar infiltrate with no signs of inflammation of the gland (x4); C, strain P4, 1 DPC, focal intra-alveolar PMN infiltration (x4); D, strain P4, 2 DPC, recovery of the gland and no inflammatory infiltrate or significant damage (x10); E, strain VL2874, 1 DPC, extensive intra-alveolar and ductal PMN infiltration (x4); F, strain VL2874, 2 DPC, partially destructed non-lactating alveoli, protein deposit and necrosis (x10); G, strain VL2732, 1 DPC, diffuse inter and intra-alveolar PMN infiltration (x10); H, strain VL2732, 2 DPC, inter-alveolar inflammatory infiltrate, necrosis, hyperemia and loss of alveoli architecture (x10); I, strain VL2732, 5 DPC, degenerative PMN, diffuse necrosis, hemorrhage, protein deposit and extensive loss of alveoli architecture (x10); J-K, strain K-12 MG1655, 1 DPC, diffuse intra-alveolar PMN infiltration without alterations to the gland structure and numerous lactating alveoli (x4-x20); L, representative picture of intra-alveolar PMN infiltration (x20). Eosine-hematoxylin stain.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4556653&req=5

pone.0136387.g001: Histological examination of mice mammary glands.A, non-pyrogenic phosphate-buffered saline (negative control), 1 DPC, no histological changes (x10); B, strain K71, 1 DPC, focal light inter-alveolar infiltrate with no signs of inflammation of the gland (x4); C, strain P4, 1 DPC, focal intra-alveolar PMN infiltration (x4); D, strain P4, 2 DPC, recovery of the gland and no inflammatory infiltrate or significant damage (x10); E, strain VL2874, 1 DPC, extensive intra-alveolar and ductal PMN infiltration (x4); F, strain VL2874, 2 DPC, partially destructed non-lactating alveoli, protein deposit and necrosis (x10); G, strain VL2732, 1 DPC, diffuse inter and intra-alveolar PMN infiltration (x10); H, strain VL2732, 2 DPC, inter-alveolar inflammatory infiltrate, necrosis, hyperemia and loss of alveoli architecture (x10); I, strain VL2732, 5 DPC, degenerative PMN, diffuse necrosis, hemorrhage, protein deposit and extensive loss of alveoli architecture (x10); J-K, strain K-12 MG1655, 1 DPC, diffuse intra-alveolar PMN infiltration without alterations to the gland structure and numerous lactating alveoli (x4-x20); L, representative picture of intra-alveolar PMN infiltration (x20). Eosine-hematoxylin stain.
Mentions: Pathogenicity in the mammary gland was studied in a murine model of intra-mammary infection. The murine model of intra-mammary infection has been widely used for the research of pathogenesis, immune response, treatment and prevention of mastitis, but only in a few instances it was used for comparison between the pathogenicity of different strains of the same pathogen species [47]. As expected, all three strains isolated from mastitis elicited clear intra-mammary inflammation in mice. Moreover, different patterns of inflammation were observed with the distinct MPEC strains on gross and histopathological examination of challenged mammary glands, and an analogy could be made between these patterns and the disease presentation observed in the mammary glands of cows originally infected by the strains studied here. For instance, strain VL2874 caused fast degeneration of mice glands within 1 DPC with extensive tissue destruction, whereas strain VL2732 caused a prolonged inflammation up to 5 DPC with a granuloma-like reaction, indicative of a chronic reaction. Comparably, the cow affected by VL2874 showed per-acute mastitis, no recovery of the affected gland to lactation, and extensive regions of gland tissue degeneration were observed histologically after culling. In contrast, VL2732 caused persistent, chronic infection in the cow mammary gland from which it was originally isolated. Compared to the two previous strains, strain P4 caused a milder inflammation in murine mammary glands. Results are summarized in Table 2 and representative histopathological images are presented in Fig 1. In accord to previous work [48], the murine model was shown to be applicable for the purpose of MPEC inter-strain comparisons. Finally, no signs of mastitis whatsoever were observed in mice challenged with strain K71, confirming that strain K71 was suitable for comparison to MPEC for the identification of potential mastitis pathogenicity-related traits.

Bottom Line: Analysis of whole genome sequences and predicted proteomes revealed high similarity among MPEC, whereas MPEC significantly differed from the non-mammary pathogenic strain K71, and from E. coli genomes from other pathotypes.Functional features identified in MPEC genomes and lacking in the non-mammary pathogenic strain were associated with synthesis of lipopolysaccharide and other membrane antigens, ferric-dicitrate iron acquisition and sugars metabolism.Among phenotypes unique to MPEC compared to the non-mammary pathogenic strain were uric acid and D-serine metabolism.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot, Israel; National Mastitis Reference Center, Department of Bacteriology, Kimron Veterinary Institute, Bet Dagan, Israel; Department of Bacteriology, Kimron Veterinary Institute, Bet Dagan, Israel.

ABSTRACT
Escherichia coli is a major etiological agent of intra-mammary infections (IMI) in cows, leading to acute mastitis and causing great economic losses in dairy production worldwide. Particular strains cause persistent IMI, leading to recurrent mastitis. Virulence factors of mammary pathogenic E. coli (MPEC) involved pathogenesis of mastitis as well as those differentiating strains causing acute or persistent mastitis are largely unknown. This study aimed to identify virulence markers in MPEC through whole genome and phenome comparative analysis. MPEC strains causing acute (VL2874 and P4) or persistent (VL2732) mastitis were compared to an environmental strain (K71) and to the genomes of strains representing different E. coli pathotypes. Intra-mammary challenge in mice confirmed experimentally that the strains studied here have different pathogenic potential, and that the environmental strain K71 is non-pathogenic in the mammary gland. Analysis of whole genome sequences and predicted proteomes revealed high similarity among MPEC, whereas MPEC significantly differed from the non-mammary pathogenic strain K71, and from E. coli genomes from other pathotypes. Functional features identified in MPEC genomes and lacking in the non-mammary pathogenic strain were associated with synthesis of lipopolysaccharide and other membrane antigens, ferric-dicitrate iron acquisition and sugars metabolism. Features associated with cytotoxicity or intra-cellular survival were found specifically in the genomes of strains from severe and acute (VL2874) or persistent (VL2732) mastitis, respectively. MPEC genomes were relatively similar to strain K-12, which was subsequently shown here to be possibly pathogenic in the mammary gland. Phenome analysis showed that the persistent MPEC was the most versatile in terms of nutrients metabolized and acute MPEC the least. Among phenotypes unique to MPEC compared to the non-mammary pathogenic strain were uric acid and D-serine metabolism. This study reveals virulence factors and phenotypic characteristics of MPEC that may play a role in pathogenesis of E. coli mastitis.

No MeSH data available.


Related in: MedlinePlus