EP1057035A2 - Procedes - Google Patents

Procedes

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Publication number
EP1057035A2
EP1057035A2 EP99905052A EP99905052A EP1057035A2 EP 1057035 A2 EP1057035 A2 EP 1057035A2 EP 99905052 A EP99905052 A EP 99905052A EP 99905052 A EP99905052 A EP 99905052A EP 1057035 A2 EP1057035 A2 EP 1057035A2
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Prior art keywords
mtimin
antisera
microorganisms
epec
raised against
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EP99905052A
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German (de)
English (en)
Inventor
Miranda Imperial College of Sc.T. & M BATCHELOR
Gordon Imperial College of Sc.Tec. & Med. DOUGAN
Gad Imperial College of Sc.Tec. & Med. FRANKEL
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Imperial College of Science Technology and Medicine
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Imperial College of Science Technology and Medicine
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/12—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria
    • C07K16/1203—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria from Gram-negative bacteria
    • C07K16/1228—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria from Gram-negative bacteria from Enterobacteriaceae (F), e.g. Citrobacter, Serratia, Proteus, Providencia, Morganella, Yersinia
    • C07K16/1232—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria from Gram-negative bacteria from Enterobacteriaceae (F), e.g. Citrobacter, Serratia, Proteus, Providencia, Morganella, Yersinia from Escherichia (G)
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/195—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria
    • C07K14/24—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria from Enterobacteriaceae (F), e.g. Citrobacter, Serratia, Proteus, Providencia, Morganella, Yersinia
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/195—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria
    • C07K14/24—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria from Enterobacteriaceae (F), e.g. Citrobacter, Serratia, Proteus, Providencia, Morganella, Yersinia
    • C07K14/245—Escherichia (G)
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/12—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria
    • C07K16/1203—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria from Gram-negative bacteria
    • C07K16/1228—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria from Gram-negative bacteria from Enterobacteriaceae (F), e.g. Citrobacter, Serratia, Proteus, Providencia, Morganella, Yersinia
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/02—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving viable microorganisms
    • C12Q1/04—Determining presence or kind of microorganism; Use of selective media for testing antibiotics or bacteriocides; Compositions containing a chemical indicator therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/569—Immunoassay; Biospecific binding assay; Materials therefor for microorganisms, e.g. protozoa, bacteria, viruses
    • G01N33/56911—Bacteria
    • G01N33/56916—Enterobacteria, e.g. shigella, salmonella, klebsiella, serratia
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K38/00—Medicinal preparations containing peptides
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2333/00—Assays involving biological materials from specific organisms or of a specific nature
    • G01N2333/415—Assays involving biological materials from specific organisms or of a specific nature from plants
    • G01N2333/425—Zeins

Definitions

  • the present invention relates to methods of detecting and/or diagnosing mtimin- expressing microorganisms such as enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli , C. rodentium and/or RDEC-1, as well as kits for use in such methods.
  • mtimin-expressing microorganisms such as enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli , C. rodentium and/or RDEC-1
  • Primers for use in such methods, as well as polypeptide regions useful in the production of antisera are also provided.
  • Vaccines based on such peptides are also described herein.
  • methods of typing/classification of such bacteria are also described herein.
  • methods for the isolation of mtimin- expressing microorganisms are also provided.
  • EPEC Enteropathogenic Escherichia coli
  • H somatic flagellar
  • A/E lesion This lesion is characterised by destruction of microvilli and intimate adherence of bacteria to cup-like pedestals formed by the bare enterocyte cell membrane (28). High concentrations of polymerised actin are present in the enterocyte beneath the site of bacterial attachment (29).
  • A/E lesions morphologically similar to those seen in biopsies, but also produces a characteristic pattern of adherence, termed localised adherence (LA) (41).
  • LA localised adherence
  • A/E lesions are also induced by other enterobacteria, including enterohemorrhagic E.
  • EHEC EHEC
  • the causative agent of bloody and non-bloody diarrhoea as well as of haemolytic uraemic syndrome in humans 40, 43
  • Hafnia alvei which has been isolated from children with diarrhoea (3)
  • Citrobacter rodentium the causative agent of transmissible colonic hyperplasia in laboratory mice (4, 42)
  • rabbit-specific EPEC strains including rabbit diarrhoeagenic E. coli (RDEC-1), which cause diarrhoea in rabbits (8)
  • EAF EPEC-adherence-factor
  • eaeA genes of several EPEC and EHEC strains, RDEC-1 and C. rodentium and the 3 1 end of eaeA of H. alvei have been cloned and sequenced (1, 5, 15, 23, 42, 49). Comparison of the amino acid sequences of the different mtimins has revealed that the N-terminal regions are highly conserved, while the C-termini show much less similarity. Nevertheless, two Cys residues at the C-termini are conserved among all the mtimin family members.
  • the present invention provides a method for detecting intimin expressing microorganisms which comprises the step of bringing into contact a sample which may (or may not) contain such microorganisms with antisera raised against one or more intimins.
  • the antisera can be either polyclonal antisera or monoclonal antisera.
  • the one or more intimins is/are derived from EPEC serotype O127:H6 and EPEC serotype O114:H2.
  • the present invention provides a method for detecting intimin expressing microorganisms which comprises the step of bringing into contact a sample which may (or may not) contain such microorganisms with antisera raised against the Gly387 to Lys666 region of eae from enteropathogenic or enterohemorrhagic microorganisms or an antigenic fragment thereof.
  • the antisera can be raised against the following polypeptides:
  • the present invention provides an isolated or recombinant polypeptide comprising the Gly387 to Lys646 region of eae from from enteropathogenic or enterohemorrhagic microorganisms or an antigenic fragment thereof.
  • DNA sequences coding for such polypeptides form a fourth aspect of the present invention.
  • Such DNA sequences can be provided in the form of vectors which can be used to transform suitable host cells for the production of antigenic polypeptide.
  • Such vectors and host cells form fifth and sixth aspects of the invention respectively.
  • the present invention provides a method for the classification/typing of intimin containing microorganisms which comprises the step of bringing into contact a sample which may (or may not) contain such microorganisms with antisera raised against one or more intimins.
  • a sample which may (or may not) contain such microorganisms with antisera raised against one or more intimins.
  • the methods will also include some form of detection step.
  • detection step The skilled person will appreciate that various means of detection can be used, including ELISA, immunoblot methods etc.
  • the present invention provides a method for detecting mtimin expressing microorganisms which comprises the step of amplifying DNA by one or more cycles of PCR from microorgamsms contained in a sample using one or more primers which allow amplification of DNA coding for one or more intimins.
  • Suitable primers for use in such methods include:
  • primers useful in amply fying this conserved region are also provided;specifically:
  • the methods are used for detection/classification/typing of EPEC and EHEC strains.
  • antisera find use in certain methods of the invention.
  • broad spectrum mtimin antisera prepared by amplifying a DNA fragment encoding for the conserved region from mtimin eg the Gly387 to Lys646 region as exemplified by EPEC strain E2348/69 DNA as a template.
  • the PCR product can then be cloned into a suitable vector and the polypeptide can be over-expressed, purified and used for antiserum production as described herein. Broad reactivity can be confirmed using conventional methods as described herein.
  • the present invention provides antisera raised against EPEC serotype O127:H6 and EPEC serotype O114:H2.
  • the antisera is polyclonal antisera.
  • antisera as described herein can be used to detect various serotypes of EPEC and EHEC as well as Citrobacter rodentium and rabbit diarrhoeagenic E.coli (RDEC-1).
  • RDEC-1 Citrobacter rodentium and rabbit diarrhoeagenic E.coli
  • the present invention provides a method for the detection of EPEC, EHEC, C.rodentium and/or RDEC-1 which comprises the step of bringing a sample into contact with antisera, eg polyclonal antisera as defined herein.
  • the present invention provides a method for the diagnosis of EPEC, EHEC, C.rodentium and/or RDEC-1 infection in a subject, ge in a human or in animal, which comprises the step of bringing into contact a biological sample obtained from the subject with antisera, eg polyclonal antisera as defined herein.
  • antisera eg polyclonal antisera as defined herein.
  • kits which comprise one or more suitable reagents such as the antisera, eg polyclonal antisera described herein.
  • suitable reagents such as the antisera, eg polyclonal antisera described herein.
  • kits form a fifth aspect of the invention.
  • kits comprising one or more of primers as described herein as well as optionally one or more reagents for use in carrying out PCR.
  • kits comprising one or more of primers as described herein as well as optionally one or more reagents for use in carrying out PCR.
  • Such kits form a final aspect of the present invention.
  • the present invention provides a method for isolating intimin-expressing microorganisms which comprises bringing into contact a sample which may (or may not) contain intimin-expressing microorganisms with antibodies raised against one or more mtimins.
  • a sample which may (or may not) contain intimin-expressing microorganisms with antibodies raised against one or more mtimins.
  • the antibodies can be used in the preparation of an immunoaffinity column, with samples being run through such that mtimin-expressing microorganisms will bind thereto.
  • aspescts there are provided:
  • an agent for use in isolating mtimin-expressing microorganisms comprising antibodies as described herein.
  • the antibody(ies) can be linked to an inert substrate, eg for use in immunocolumn;
  • the work described herein provides the basis for a vaccine approach to prevention/therapy based on the conserved region of the mtimin protein.
  • the present invention provides:
  • medicament for the prevention and/or treatment of enteropathogenic and/or enterohemorrhagic microorganisms iii) a method for the prevention and/or treatment of infection by enteropathogenic and/or enterohemorrhagic microorganisms which comprises the step of administering an effective amount of a polypeptide as described herein.
  • Fig. 1 shows immunoblotting analysis of polyclonal antisera against various EPEC strains. 0.05 OD of each sample was loaded onto a 7.5% SDS-PAGE and the bacterial cell extracts were reacted with anti-Int280-H6 (A) or anti- Int280-H2 (B). Molecular weight markers (in kilodaltons) are shown in lane 1.
  • Fig. 2 shows immunogold labelling of logarithmic phase DMEM grown cultures of EPEC (a-c) and EHEC (d) and immunofiuorescence labelling of HEp-2 cell adherent EPEC (e-g) and EHEC strains (h-1) showing: an O127:H6 EPEC strain expressing mtimin ⁇ (a, e); an O114:H2 EPEC strain expressing intimin ⁇ (b, f); an O86:H34 EPEC strain that expresses neither mtimin ⁇ nor ⁇ (c, g); an O157:H7 EHEC strain expressing neither mtimin ⁇ nor ⁇ (d, h); an 026 :H" EPEC strain expressing mtimin ⁇ (i) and an O26:Hll EHEC strain expressing mtimin ⁇ (j) Dut not mtimin ⁇ (k). Although not stained with anti mtimin ⁇ , the phase contrast micrograph of the same field as k shows
  • Fig. 3 shows detection of mtimin ⁇ and intimin ⁇ by PCR. Representative strains are shown. PCR products with Int ⁇ primer were obtained from E2348/69 (A, lane 2) and from all of the tested O55:H6 (A, lanes 4-9), but with none of the Olll:H2 (B, lanes 2-9) or CVD206 (A, lane 3). All the tested O119:H2 (C, 2-7) and O119:H6 (D, 2-7) strains produced a positive PCR product using the Int ⁇ primer. In lane 1 of each panel molecular weight markers (1 Kb ladder, BRL) were loaded. The complete DNA analysis is presented in Table 3.
  • Bacterial strains used in this study included clinical EPEC strains serotypes O127:H6 (E2348/69) (34) and ICC64 (15), O114:H2 (ICC61) (21), Olll:H- (B171) (18) and O86:H34 (ICC95); an eaeA 0127 :H6 mutant (CVD206) (10) and the strains listed in Tables 1 and 2.
  • Bacterial strains were grown in L-broth or L-agar. Media was supplemented with lOO ⁇ g/ml ampicillin or 30 ⁇ g/ml kanamycin where appropriate.
  • MBP-Int280 fusion protein from EPEC ICC64 (Int280-H6) was purified as previously described (15).
  • the cells were harvested by centrifugation, the supernatant discarded, and the pellet was re- suspended in 8 ml binding buffer (5 mM imidazole, 0.5 M NaCl, 20 mM Tris-HCl, pH 7.9) and frozen overnight.
  • the culture was then sonicated at maximum intensity in 10 sec bursts for a total of 3 min with 1 min intervals.
  • the lysate was centrifuged at 3,200 x g for 30 min and the supernatant was loaded onto a 2.5 ml bed volume pre-washed nickel column.
  • the column was washed with the following solutions - 25 ml binding buffer, 7.5 ml wash buffer 1 (30 mM imidazole, 0.5 M NaCl, 20 mM Tris-HCl, pH 7.9) and 7.5 ml wash buffer 2 (60 mM imidazole, 0.5 M NaCl, 20 mM Tris-HCl, pH 7.9).
  • the bound protein was eluted with 15 ml elute buffer (500 mM imidazole).
  • the fractions were analysed on a 10% polyacrylamide gel electrophoresis (see below).
  • Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS) was performed as described by Laemmli (31). Protein samples and bacterial extracts to be separated were diluted in an equal volume of 2 x sample buffer (2% SDS [w/v], 2% 2-mercaptoethanol [v/v], 20% glycerol, and 0.01% bromophenol blue [w/v] in 0.0065 M Tris pH 6.8) and boiled for 5 min prior to loading onto 7.5-10% gels. Molecular weights were estimated using Rainbow molecular markers (Amersham). Following electrophoresis the separated proteins were visualised by staining the gel with Coomassie stain or transferred to nitrocellulose membrane.
  • SDS sodium dodecyl sulphate
  • Proteins separated by SDS-PAGE were transferred electrophoretically onto nitrocellulose membranes (Schleicher and Schuell) and immunoblotted according to Towbin et al (44) and Burnette (6), at 80v for 90 min.
  • the membranes were blocked overnight in 3% bovine serum albumin (BSA), washed three times with phosphate buffered saline (PBS) containing 0.05% Tween 20 (PBST) and then reacted with the anti-serum of interest for 2 h.
  • BSA bovine serum albumin
  • PBS phosphate buffered saline
  • PBST 0.05% Tween 20
  • Anti-Int280-H6 and anti-Int280-H2 sera were diluted 1:750 and 1:5000 respectively in PBST containing 0.1% BSA.
  • 96 well ELA/RIA plates (Costar) were coated overnight at 4°C with 50 ⁇ l/well of 2.5 ⁇ g/ml of Int280 in PBS. The wells were washed three times in PBST and blocked for 1 h at 37°C with PBST-1% BSA. The plates were washed again and then incubated with 5 fold-serial dilutions of the primary antibody in order to determine the antiserum titre. Two hour incubations with primary and secondary antibodies, diluted in PBST-0.1%BSA, were carried out at 37°C with PBST washes after each step.
  • HEp-2 cell preparations were also labelled for cellular actin by simultaneously staining coverslips with a 5 ⁇ g/ml solution of TRITC-phalloidin (Sigma) (30). Preparations were washed three times with PBS, mounted in glycerol-PBS and examined by incident light fluorescence using a Leitz Dialux microscope. Fluorescence and phase contrast images of the same field were recorded.
  • the DNA sequence of Int280 from ICC61 was determined from the recombinant pET28a construct and from three independent Taq polymerase (Appligene) PCR products cloned into pGEM-T vector (Promega).
  • the DNA sequence of Int280 from ICC95 was determined from a vent polymerase (New England Biolabs) PCR product cloned into pGEM-T.
  • Primers used were pET28 T7 promoter (5' TTAATACGACTCACTATAGG), pET28 T7 terminator (5* CTAGTTATTGCTCAGCGGT), pGEM-T VI (5' TGTAAAACGAAGGCCAGT) and pGEM-T V2 (5' ATGTTGTGTGAATTGTG).
  • Plasmids were purified from 4.5ml overnight culture. After centrifugation the bacterial pellets were resuspended in 200 ⁇ l of 50 mM Tris-HCl pH 7.5 and 10 mM EDTA solution containing lOO ⁇ g/ml RNaseA. 200 ⁇ l lysis solution (0.2 M NaOH, 1% SDS) was added before the mixtures were neutralised with 200 ⁇ l 1.32 M potassium acetate pH 4.8. Following 5 min centrifugation, the supernatants were extracted twice with 400 ⁇ l chloroform and the plasmid DNA was precipitated in an equal volume of isopropanol.
  • DNA sequencing was performed using 0.5-l ⁇ g of template DNA and a vector-derived primer using an Perkin Elmer ABI/Prism 377 automated DNA sequencer according to manufacturers instructions.
  • GenBank database under accession numbers 111 and 222, respectively.
  • PCR (37) was used to amplify a segment of the eaeA gene. Thirty amplification cycles of 95°C 20 sec; 45°C 1 min and 74°C 1 min (except for the Int ⁇ primer for which the annealing temperature was 55°C) were employed. 25 pmol of each of the primers (Table 2) and 1.5 units Taq DNA polymerase (Appligene, Durham, UK) were used. For each reaction, about one third of a colony was transferred to a 0.5 ml tube containing the PCR reaction mixture and primers and the tubes were incubated at 95°C for 5 min prior to the PCR cycling. lO ⁇ l from each reaction were analysed by agarose gel electrophoresis
  • mtimin expression is induced when EPEC is grown to the mid-log growth phase in DMEM at 37°C.
  • mtimin was undetectable when the DMEM cultures were incubated at 28°C (data not shown).
  • Fig 1 shows immunoblotting of fourteen representatives of these strains (summary in Table 1). No reactivity was observed when the strains were probed with normal rabbit serum (data not shown). These findings show antigenic variation within the cell binding domain and indicate that by using these sera, mtimin can be divided antigenically into at least three serogroups (Table 1). These were designated mtimin ⁇ , recognised strongly by anti-Int280-H6 serum; mtimin ⁇ , recognised strongly by anti-Int280-H2; and non-typable (NT), recognised poorly by either antiserum (Table 1).
  • Anti-mtimin ⁇ antiserum was 100-fold more reactive with MBP-Int280 O127:H6 (ICC64) compared with MBP-Int280 O114:H2 and Olll:H" (ICC61 and B171 respectively).
  • the anti-mtimin ⁇ antiserum was 10-fold more reactive with MBP-Int280 (ICC61 and B171) than with MBP-Int280 (ICC64). No reactivity was observed with MBP.
  • strains belonging to serogroups O55:H6, O127:H6, O142:H6 and O142:H34 stained strongly with anti- intimin ⁇ serum, while strains belonging to serogroups O55:H”, O86:H34, Olll:H", Olll:H2, O114:H2, O119:H2, O119:H6 and O127:H40 showed weak or no staining (Fig. 2a and e and Table 1).
  • rodentium (42); 46.7% identity with O157:H7 (49); 100% identity with RDEC-1 (1), O26:Hll (Genebank accesion number U62656) and O26:B6 (Genebank accesion number U62657); 99.6% identity with Olll:H” (Genebank accesion number U62655) and 47% identity with H. alvei (15).
  • Comparison of Int280 from ICC95 with those of E2348/69 and O157:H7 revealed 49.6% and 46.7% identity, respectively, 47% and 77.6% identity respectively with H. alvei and C. rodentium while 75% identity with those of E. coli RDEC-1 and seotypes O114:H2, Olll:H-,O26:Hll and O26:B6 was revealed.
  • strains which belong to EPEC clone 1 were also positive in PCR using the Int- ⁇ primer.
  • the second group included strains that reacted strongly with anti-mtimin ⁇ serum. These strains (serotypes Olll:H2, OllLH", O114:H2, O119:H2, O119:H6 and O128:H2), with the exception of O119:H6 (20) all belong to EPEC clone 2 (39, 46) and produced a positive PCR product when the Int- ⁇ primer was used.
  • EHEC strains capable of forming A/E lesions and lacking the EAF plasmid are also divided into two divergent clonal groups (46, 47).
  • EHEC clone 1 includes the serotype O157:H7 clone while EHEC clone 2 composed of shiga-like toxin- producing serotype O26:Hll and Olll:H8 strains. Recently, it was shown that serotype O55:H7, an atypical EPEC clone, is closely related to EHEC clone 1 (46, 47).
  • Bacterial strains Bacterial strains used in this example included E. coli BL21, clinical EPEC strains serotypes O127:H6 (E2348/69) (34), Olll:H- (B171) (18), O55:H7 (ICC57) (this study), an eae O127:H6 mutant (CVD206) (10) and the strains listed in Table 6. Bacterial strains were grown in L-broth or L-agar. Media was supplemented with 100 mg/ml ampicillin or 30 mg/ml kanamycin where appropriate.
  • Polyacrylamide gel electrophoresis Polyacrylamide gel electrophoresis (PAGE) in the presence of sodium dodecyl sulphate (SDS) was performed as described by Laemmli (31). Protein samples and bacterial extracts to be separated were diluted in an equal volume of 2 x sample buffer (2% SDS [w/v], 2% 2-mercaptoethanol [v/v], 20% glycerol, and 0.01% bromophenol blue [w/v] in 0.0065 M Tris pH 6.8) and boiled for 5 min prior to loading onto 7.5-10% gels. Molecular weights were estimated using Rainbow molecular markers (Amersham). Following electrophoresis the separated proteins were visualised by staining the gel with Coomassie stain or transferred to nitrocellulose membrane.
  • SDS sodium dodecyl sulphate
  • PCR Polymerase chain reaction
  • Immunogold labelling of bacterial cells For immunogold labelling of bacteria, stationary phase L-broth cultures of representative strains were diluted 1:100 in DMEM and grown at 37 ⁇ C for 4 h. 10 ml samples of washed bacterial suspensions were applied to carbon coated grids for 5 min, excess liquid removed, and grids immediately placed face down on drops of anti Int280-H6 or anti Int280-H2 sera (diluted 1:40 in PBS containing 0.2% BSA — PBS/BSA) for 30 min. After thorough washing in PBS/BSA, grids were placed on drops of 10 nm gold-labelled goat anti-rabbit sera (diluted 1:20 [British BioCell International]) for 30 min. After further washing with PBS/BSA and distilled water grids were air dried and viewed under an Jeol 1200EX electron microscope operated at 80kV.
  • Immuno-fluorescent labelling of bacterial cells Immuno-fluorescent staining was performed on bacteria adhering to HEp-2 cells following a 3 h incubation of HEp-2 cell monolayers with overnight cultures (30). Formalin fixed and washed infected cell monolayers were incubated with the universal antiserum (diluted 1:40) for 45 min. After three 5 min washes with PBS/BSA monolayers were stained with FLTC- conjugated goat anti rabbit IgG (Sigma, diluted 1:20) for 45 min. HEp-2 cell preparations were also labelled for cellular actin by simultaneously staining coverslips with a 5 mg/ml solution of FTTC-phalloidin (Sigma) (30). Preparations were washed three times with PBS, mounted in glycerol-PBS and examined by incident light fluorescence using a Leitzs Dialux microscope. Fluorescence and phase contrast images of the same field were recorded.
  • the Int280-Con polypeptide was over expressed in E. coli BL21, the protein purified on a nickel column and used to raise rabbit polyclonal antiserum. The specificity of the antiserum was confirmed using wild-type (E2348/69) and its eae minus derivative (CVD206) on Western blots and Immunogold EM (Fig. 1 and 2).
  • the aim of this study was to develop a broad spectrum intimin antiserum, reactive with all of the mtimin types, expressed by A/E lesion forming microbial pathogens.
  • Reacting the antiserum with Western blots of eae+ EPEC and non-E. coli strains revealed that the antiserum can recognise any of the mtimin types. Similar level of reactivity was observed with all the strains harbouring the Per regulatory proteins, while lower mtimin levels were detected on the EAF negative strains.
  • immunogold EM we have observed variations in surface exposure of this regions.
  • Sera were from 14 patients with faecal E. coli 0157 VTEC expressing VT2 only, and with serum antibodies to the 0157 LPS antigens. Twenty sera, obtained from apparently healthy individuals, originated from the blood transfusion service, London, UK, were used as controls. SDS-PAGE/ immunobloting. SDS-PAGE was performed using the method of Laemmli [1970] with an Atto mini-gel system (Genetic Research Instrumentation Ltd.). Preparations containing 10 ⁇ g protein in 5 ⁇ l SDS-PAGE solubilisation buffer were incubated at 100°C (5 mins) prior to loading onto gels comprising a 4.5% acrylamide stacking gel and a 12.5% acrylamide separation gel. Following electrophoresis (50 mAmp, 30 min), gels were either stained with Coomassie brilliant blue or used for immunobloting.
  • Sera were obtained from 14 patients with faecal E. coli 0157 VTEC expressing VT2 only, and with serum antibodies to the 0157 LPS antigens.
  • Nine patients were infected with E. coli 0157 belonging to phage type 2 and three strains belonged to phage type 21 (Table 1).
  • Seven patients were female (mean age 9.4 ( 11.7 years) and seven were male (mean age 7.7 ( 3.6 years). Twelve patients were known to have had HUS (Table 1). Samples of serum and faeces had been referred to the Laboratory of Enteric Pathogens as part of the routine surveillance of VTEC infection in England and Wales.
  • EHEC isolation and characterisation of EHEC from patients' stools is usually performed to identify the cause of disease, while the detection of vtx genes or free VT in faeces can indicate the possible involvement of VTEC. It is not always possible to obtain evidence of EHEC infection using the methods described above, so serological tests based on purified lipopolysaccharide (LPS) have been developed to provide evidence of infection with E. coli 0157 and other serogroups . In this study we provide further evidence that mtimin is expressed during infection with VTEC and that the conserved region of the outer membrane protein adhesin, may be useful to develop an alternative sero-diagnosis test to VTEC infection.
  • LPS purified lipopolysaccharide
  • Values in parentheses are numbers of positve isolates/total number of strains tested

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Abstract

La présente invention concerne des procédés permettant de détecter et/ou de diagnostiquer la présence de micro-organismes exprimant l'intimine, tels que l'Escherichia coli entérophatogène, l'Escherichia coli entérohémorragique, le C. rodentium et/ou le RDEC-1, ainsi que des trousses à utiliser avec ces procédés. L'invention se rapporte en particulier à des antisérums dirigés contre des régions conservées obtenus selon les procédés de l'invention, et à des régions polypeptidiques utilisées dans la production des antisérums. L'invention concerne également des vaccins basés sur ces peptides, ainsi que des procédés de typage/classification des bactéries précitées. L'invention se rapporte enfin à des procédés permettant d'isoler les micro-organismes exprimant l'intimine.
EP99905052A 1998-02-16 1999-02-16 Procedes Withdrawn EP1057035A2 (fr)

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GB9908525D0 (en) * 1999-04-14 1999-06-09 Imperial College Methods
CA2339436A1 (fr) 2001-03-15 2002-09-15 Josee Harel Production d'anticorps contre les facteurs de virulence associes aux souches d'escherichia coli aeec, et leur utilisation
WO2002079240A2 (fr) * 2001-03-29 2002-10-10 Imperial College Innovations Limited Substances biologiques et procedes pour leur utilisation dans la prevention ou le traitement d'infections
WO2003052143A2 (fr) * 2001-12-19 2003-06-26 Angles D Auriac Marc B Nouvelles amorces pour la detection et l'identification de groupes d'indicateurs bacteriens
CN1253571C (zh) * 2004-03-12 2006-04-26 天津生物芯片技术有限责任公司 对大肠杆菌o114型的o－抗原特异的核苷酸

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CA2078716A1 (fr) * 1992-09-21 1994-03-22 Joyce De Azavedo Proteine de e. coli enterohemorragique de fixation et de destruction
US5747293A (en) * 1995-03-23 1998-05-05 Imperial College Of Science, Technology & Medicine Intimin-like proteins of E. coli
AU722327B2 (en) * 1996-04-19 2000-07-27 Henry M. Jackson Foundation For The Advancement Of Military Medicine Method of stimulating an immune response by administration of host organisms that express intimin alone or as a fusion protein with one or more other antigens
WO1997040161A1 (fr) * 1996-04-19 1997-10-30 Henry M. Jackson Foundation For The Advancement Of Military Medecine Intimine marquee a l'histidine et procedes d'utilisation de l'intimine pour stimuler une reaction immunitaire et en tant que porteur d'antigene a capacite de ciblage

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