COMPOSITIONS FOR THE INHIBITION OF GIARDIA LAMBLIA

Abstract

The present invention relates to a composition exhibiting a bile-salt hydrolase activity for its use for the treatment or the prevention of giardiasis, said composition comprising a bile-salt hydrolase (BSH) enzyme, a bacterium able to secrete a BSH, a recombinant host cell able to secrete a BSH, or a combination thereof. The present invention also relates to the use of a composition exhibiting a BSH activity for the treatment or the prevention of giardiasis, and to a pharmaceutical composition or a food composition comprising, as an active principle, a BSH, a lactic acid bacterium able to secrete a BSH, or a recombinant host cell able to secrete a BSH.

Claims

1. Composition exhibiting a bile-salt hydrolase activity for use for the treatment or the prevention of giardiasis, wherein said composition is chosen in the group consisting of: a composition comprising at least one bile-salt hydrolase (BSH) enzyme, a composition comprising a lactic acid bacterium able to secrete at least one BSH enzyme, with the exception of Lactobacillus johnsonii La1, Lactobacillus acidophilus, Bifidobacterium bifidum and Bifidobacterium infantis. a composition comprising a recombinant host cell able to secrete at least one heterologous BSH enzyme, and a combination thereof, wherein said bile-salt hydrolase activity is determined by the detection of the presence of glycine or taurine liberated from conjugated bile salts, of cholic acid, of deoxycholic acid and/or of chenodeoxycholic acid.

2. The composition for use according to claim 1, wherein said bile-salt hydrolase activity is associated with the presence of at least one bile-salt hydrolase (BSH) enzyme.

3. The composition for use according to claim 2, wherein said BSH enzyme is chosen among BSH from prokaryotes, and preferably among BSH from lactic acid bacteria.

4. The composition for use according to any one of claims 1 to 3, wherein said BSH enzyme comprises an amino acid sequence having at least 80% identity with, or is a natural variant of, an amino acid sequence chosen in the group consisting of: Lactobacillus johnsonii La1 BSH-12 (SEQ ID No 1), Lactobacillus johnsonii La1 BSH-47 (SEQ ID No 2), Lactobacillus johnsonii La1 BSH-56 (SEQ ID No 3), Lactobacillus gasseri BSH-A (SEQ ID No 4), Lactobacillus gasseri BSH-B (SEQ ID No 5), Lactobacillus johnsonii DPC 6026 BSH (SEQ ID No 6), Lactobacillus johnsonii DPC 6026 BSH (SEQ ID No 7), and Lactobacillus johnsonii DPC 6026 BSH (SEQ ID No 8).

5. The composition for use according to any one of claims 1 to 4, said composition comprising a lactic acid bacterium able to secrete a BSH, wherein said bacterium is chosen among: Lactobacillus, with the exception of Lactobacillus johnsonii La1 and of Lactobacillus acidophilus, Bifidobacterium, with the exception of Bifidobacterium bifidum and Bifidobacterium infantis.

6. The composition for use according to claim 5, wherein said lactic acid bacterium is a Lactobacillus chosen in the group consisting of: Lactobacillus johnsonii, with the exception of Lactobacillus johnsonii La1, Lactobacillus gasseri, Lactobacillus acidophilus, with the exception of Lactobacillus acidophilus La10, and Lactobacillus reuteri.

7. The composition for use according to claim 5 or 6, wherein said Lactobacillus is chosen in the group consisting of the bacterial strains referenced as: Lactobacillus johnsonii: filed at CNCM, Institut Pasteur, Paris, France, under reference I-4885, on Aug. 7, 2014 Lactobacillus gasseri: filed at CNCM, Institut Pasteur, Paris, France, under reference I-4884, on Aug. 7, 2014.

8. A host cell for use for the treatment or the prevention of giardiasis, said host cell comprising an heterologous nucleic acid comprising at least one of the following nucleotide sequences: nucleotide sequence encoding for L. johnsonii La1 BSH-12 (SEQ ID No 9), or a natural variant thereof, nucleotide sequence encoding for L. johnsonii La1 BSH-47 (SEQ ID No 10), or a natural variant thereof, nucleotide sequence encoding for L. johnsonii La1 BSH-56 (SEQ ID No 11), or a natural variant thereof. wherein said host cell is able to secrete a BSH enzyme.

9. A host cell according to claim 8, wherein said host cell is a lactic acid bacterium.

10. Composition for use in the treatment or the prevention of giardiasis according to any one of claims 1 to 7, for the treatment or the prevention of giardiasis in human beings.

11. Composition for use in the treatment or the prevention of giardiasis according to any one of claims 1 to 7, for the treatment or the prevention of giardiasis in animals, and in particular for pigs and cows.

12. Pharmaceutical composition comprising, as an active principle, a composition exhibiting a bile-salt hydrolase activity according to any one of claims 1 to 7, and a pharmaceutically acceptable carrier,

13. Food composition or dietary supplement comprising, as an active principle, a composition exhibiting a bile-salt hydrolase activity according to any one of claims 1 to 7, and a carrier.

14. Process for the preparation of a pharmaceutical composition according to claim 12 or for the preparation of a food composition or dietary supplement according to claim 13, said process comprising a step of contacting a carrier and at least one of the following elements, or a combination thereof: A bile-salt hydrolase (BSH) enzyme, A bacterium able to secrete at least one BSH, with the exception of the bacterial strains Lactobacillus johnsonii La1 (public reference NCC533, CNCM I-1225), Lactobacillus acidophilus La10 (NCC90, CNCM I-2332), Bifidobacterium bifidum (NCC189, CNCM I-2333) and Bifidobacterium infantis (NCC200, CNCM I-2334), A recombinant host cell able to secrete at least one BSH.

Description

LEGENDS OF THE FIGURES

[0140] FIGS. 1A and 1B: inhibitory effect of LjLa1 supernatant on G. lamblia. FIG. 1A represents parasites concentration as a function of incubation time in the presence of KM-FCS with (filled symbols) or without (open symbols) bovine bile (0.75 g/L, final concentration), in presence (squares) or absence (diamonds) of bacterial supernatant (LjLa1sn). The parasite concentration was estimated by counting lived cells with a Malassez cell chamber, as indicated in example 1. N=2. FIG. 1B represents the percentage of G. lamblia growth inhibition after 24 h of culture is expressed as a function of bile salts concentration (grey histograms) or of complete bovine bile (black histograms, right part of the figure). G. lamblia trophozoites in KM-FCS were incubated for 24 h at 37° C. in anaerobic conditions with LjLA1sn and various concentrations of bile salts (0.016, 0.032, 0.048 g/L, final concentration) or complete bovine bile (0.5, 0.6, 0.75 g/L, final concentration). Growth inhibition values (%) were normalized according to control in lactic acid-acidified KM-FCS supplemented with similar concentrations of bovine bile or bile salts. Number of independent experiments=3.

[0141] FIGS. 2A to 2C: percentage of G. lamblia growth inhibition after 24 h of culture. FIG. 2A represents the percentage of G. lamblia in the presence of (from left to right) LjLa1sn with no protease treatment, LjLa1sn with proteinase K, LjLa1sn with pronase; LjLa1sn with catalase or heated at 90° C. for 10 min before G. lamblia growth inhibition assay. Growth inhibition (%) was normalized according to matched control: lactic acid-adjusted MTYI medium incubated with protease-coupled beads or treated for 10 min at 90° C. Number of independent experiments=3. FIG. 2B represents the percentage of G. lamblia growth inhibition after 24 h of culture in varying pH. Supernatant from LjLa1 in MTYI medium was adjusted to pH 6.2, 6.7, 6.9 or 7.2 (histograms from left to right) before Giardia growth inhibition assays. Growth inhibition (%) was normalized according to control, i.e. lactic acid-adjusted MTYI subsequently raised to pH 6.2, 6.7, 6.9 or 7.2. Number of independent experiments=3. FIG. 2C represents the percentage of G. lamblia growth inhibition after 24 h of culture in supernatant from a culture of LjLa1 in KM-FCS medium filtrated through a 10 kDa, 30 kDa or 50 kDa MW cut-off membrane (from left to right). Acidified KM-FCS alone was processed similarly. Fractions above and under respective thresholds were assayed for Giardia growth inhibition in presence of bile (0.5 g/L). Inhibition values (%) were normalized according to KM-FCS controls. Number of independent experiments=3.

[0142] FIGS. 3A to 3C: impact of LjLa1 supernatant on bovine bile composition, as shown by total ion chromatograms detected by LC-MS of the SPE-treated samples corresponding to an incubation of the bile for 24 h at 37° C. with either KM medium alone (FIG. 3A), LjLa1 supernatant (FIG. 3B) or heat-treated LjLa1 supernatant (FIG. 3C). Metabolic profiles were established, from which the main components were identified using Metlin (Smith et al., 2006) or LMSD (Sud et al., 2007) databases, or from their MS/MS fragmentation pattern. TC: taurocholate, GC glycocholate, TCDC: taurochenodesoxycholate, TDC: taurodesoxycholate, GCDC: glycochenodesoxycholate, GDC: glycodesoxycholate, C: cholate, CDC: chenodesoxycholate, DC: desoxycholate.

[0143] FIGS. 4A and 4B: Increase of non-conjugated salts cholate and deoxycholate content after treatment of bile with LjLa1 supernatant. FIGS. 4A and 4B represent boxplot showing the relative intensity of cholate (C) and desoxycholate (DC) for the bile incubated in the absence (left) presence (right) of LjLa1 supernatant.

[0144] FIGS. 5A to 5C: G. lamblia growth inhibitory activity and BSH activity co-eluate in the same fractions after separation of LjLa1 supernatant by gel filtration chromatography. FIG. 5A: Chromatography profile. FIG. 5B: BSH activity measured after 24 h of incubation of GDC (2.4 g/l) with gel filtration fraction collected. FIG. 5C: G. lamblia growth inhibitory activity after 24 h of incubation with gel filtration chromatography fractions in presence of GDC (0.2 g/l).

[0145] FIG. 6: Inhibition of Giardia lamblia growth by enzymatically active C. perfringens BSH in the presence of glycine- (GDC, GCDC) or taurine- (TDC, TCDC) conjugated bile salts. Commercial C. perfringens BSH, enzymatically active (dark bars) or inactivated (light bars) by a heat-treatment (100° C., 5 min) was added to G. lamblia growth medium. GDC: glycodesoxycholate, GCDC: glycochenodesoxycholate, TDC: taurodesoxycholate, TCDC: taurochenodesoxycholate.

[0146] FIGS. 7A to 7D: Measurement of G. lamblia inhibition by flow cytometry.

[0147] FIG. 8: Percentage of living G. lamblia parasites when cultivated in the presence of varying Lactobacillus strains.

[0148] FIG. 9: Enzymatic activity of recombinant BSH-47 produced in E. coli. E. coli wild type or E. coli secreting BSH-47 were incubated in the presence of taurodeoxycholic acid 0.3% (upper panels) or in the presence of glycodeoxycholic acid 0.3% (lower panels).

[0149] FIG. 10: Histogram representing the number of living Giardia parasites (in cells per ml) after incubation with (from left to right) medium, medium and bile, C. perfringens BSH (1 U), C. perfringens and bile, recombinant BSH-47, recombinant BSH-47 and bile.

[0150] FIGS. 11A and 11B: Inhibition of Giardia lamblia growth by enzymatically active recombinant BSH from LjLA1 in the presence of bovine bile (0.6 g/L) after 20 h of incubation. FIG. 11A represents the inhibition of G. lamblia growth by recombinant BSH-47. FIG. 11B represents the inhibition of G. lamblia growth by recombinant BSH-56.

[0151] FIGS. 12A and 12B: G. lamblia cysts or trophozoites counts after administration to animals. Newborn mice received either PBS, LjLa1 or L. gasseri CNCM I-4884 by intragastric gavage (5.Math.10.sup.8 CFU/mice) daily from day 5 before inoculation with the trophozoites of G. lamblia WB clone C6 (10.sup.5 trophozoites per animal). Gavages were performed until day 15 (n=8 to 12/group). FIG. 12A: Giardia trophozoites count in the small intestine. Values are mean±SEM; p<0.05. FIG. 12B: Giardia cysts counts in large intestine of mice belonging to different groups. Values are mean±SEM; p<0.05.

[0152] FIG. 13: G. lamblia trophozoites count in the small intestine. Mice were challenged with the trophozoites of G. lamblia WB clone C6 (10.sup.5 trophozoites per animal) at day 10 Animals were treated either with PBS or BSH-47 at 1 μg/ml (0.5 μg per mice), 10 μg/ml (5 μg per mice) or 100 μg/ml (50 μg/mice) by daily intragastric gavage until day 15 (n=10 to 11/group). Values are mean±SEM; p<0.05.

EXAMPLES

Example 1: Material and Methods

Products and Preparation of Stock Solutions

[0153] Bovine bile solutions (Sigma and Difco) were prepared at 100 mg/ml stock solution in distilled water, filtered at 0.2 μm and stored at −20° C. Pure bile salts (Sigma): glycocholate (GC), taurocholate (TC), glycodeoxycholate (GDC), taurodeoxycholate (TDC), glycochenodeoxycholate (GCDC) and taurochenodeoxycholate (TCDC), bile salt mix (Sigma) or pure corresponding bile salts (Sigma): cholate (C), deoxycholate (DC) and chenodeoxycholate (CDC), and fusidic acid (Sigma) were dissolved in distilled water to 12 mg/ml stock solution, filtered at 0.2 μm and kept at −20° C. Choloylglycine Bile Acid Hydrolase (or Bile Salt Hydrolase, BSH, EC 3.5.1.24) from Clostridium perfringens (Sigma) was prepared at 10 U/ml in distilled water (milli-Q grade) and stored at −20° C. Iodoacetic acid (Sigma) was prepared as 0.5 M stock solution in distilled water and frozen at −20° C. Fetal calf serum was from PAA Laboratories, GE Healthcare. The NEFA-C kit used for quantitative determination of non-esterified fatty acids (NEFAs) was from Biolabo (WAKO Diagnostics).

Cell Culture of Giardia lamblia

[0154] Trophozoites of G. lamblia strains WB (clone C6, ATCC30957) and HP1 (Portland-1, gift of J. Tackezy) were grown as previously described in TYI-S-33 Keiser's medium (KM) with some modifications. TYI-S-33 was adjusted at pH 6.0, supplemented with 10% heat-inactivated fetal calf serum (Paget et al., 2004) and 0.6 mg/ml bovine bile (Carnaby et al., 1994). They were regularly subcultured at a density of 5×10.sup.4 cells per tube (12 ml) from log phase parasites chilled on ice for 10 min and centrifuged at 700×g, 5 min.

Culture of Lactobacillus johnsonii and Production of Bacterial Supernatant

[0155] L. johnsonii La1 (LjLa1), CNRZ 1897, NCC533, was kindly provided by Pascal Quénée (INRA Jouy en Josas, Equipe Atalis) and has been isolated from LC1 product in 1996 (Chambourcy, France). LjLa1 stock cultures were kept frozen in MRS Broth media with 15% glycerol. Bacteria were subcultured in MRS Broth medium (Sigma) or modified TYI-S-33 medium (MTYI) (Pérez et al. 2001) and incubated anaerobically for 12-18 h at 37° C. Bacteria were subsequently grown in MTYI or KM medium supplemented or not with 10% heat-inactivated fetal calf serum for 12-16 h in the presence or absence of 0.6 mg/ml bovine bile. After centrifugation (3,000×g, 10 min) and 0.2 μm filtration, the pH of the bacterial supernatant was adjusted to 6.0, 6.2, 6.7, 6.9 or 7.2 with 5 N NaOH. Appropriated controls were prepared as follows: lactic acid produced during growth was quantified from aliquots of supernatants (Enzytec™ kit, R-Biopharm) and equivalent amount of lactic acid was added to fresh medium before pH adjustment.

In Vitro G. lamblia Growth Inhibition Assay

[0156] One milliliter of trophozoites suspension (1×10.sup.5 parasites/ml in KM supplemented with 10% fetal calf serum but without bovine bile) was mixed with either 500 μl of bacterial supernatant or bile salt hydrolase from C perfringens (BSH, 0.2, 1 or 2 U) or appropriate controls in KM or MTYI, in the presence of different concentrations of either bovine bile (0 to 0.6 mg/ml), mixed bile salts (0 to 0.2 mg/ml), conjugated bile salts (0 to 0.2 mg/ml) or deconjugated bile salts (0 to 0.2 mg/ml). Samples were incubated for 24 h at 37° C. and then chilled on ice for 10 min to dislodge trophozoites from tube wall. Living trophozoites (parasites with pear shape showing signs of flagella mobility) were counted using Malassez cell chamber and/or using an hemocytometer. Multiplication factor (i.e. number of total trophozoites at the end of the experiment/number of trophozoites at time zero), survival rate (i.e. (number of living cells/total number of trophozoites)×100) and inhibition percentage (i.e., 100−(number of living cells in the presence of tested compounds/number of living cells in control)×100) were calculated.

Partial Purification of Active Fractions from Bacterial Supernatants by Gel Filtration

[0157] Supernatants from LjLa1 cultures in MTYI or KM, adjusted to pH 6.0, were concentrated up to 30-fold by ultrafiltration using 10 kDa Centriprep centrifugal filter unit (Millipore). After 0.2 μm filtration, the concentrated supernatants were placed on a Sephacryl 5300 column 16/100 (GE Healthcare) previously equilibrated with 20 mM ammonium sulfate, pH 6.0, in a cold room and were eluted with the same buffer at a flow rate of 1.8 to 2.0 ml/min. Twelve effluent fractions of 12 ml were obtained, concentrated 4-fold by ultrafiltration on a 10 kDa Centriprep as described above, and tested for Giardia inhibition by classical in vitro growth inhibition assays in the presence of bovine bile or bile salts. Fractions obtained by similar processing of elution buffer alone and control media containing lactic acid (see above) were used as controls. Column calibration was carried out with ribonuclease A (13,700 Da) and bovine serum albumin (67,000 Da).

Characterization of the Active Molecule(s) in LjLa1 Supernatant

[0158] Molecular size of active molecule(s) present in the bacterial supernatant was assessed by ultrafiltration using 10 kDa, 30 kDa and 50 kDa Centriprep centrifugal filter units. Thermal stability was tested by heating bacterial supernatant at 90° C. for 10 minutes. Preservation of the LjLa1 supernatant activity upon dialysis was checked by dialyzing twice (for 2 h and 15 h at 4° C., respectively) the supernatant against 100 volumes of KM medium supplemented with 10% FCS or against GKN solution (Perez et al., 2001) (NaCl, 8 g/l; KCl, 0.4 g/l; glucose, 2 g/l; NaH.sub.2PO.sub.4, H.sub.2O, 0.69 g/l; Na.sub.2HPO.sub.4, 1.57 g/l; pH 7.2 to 7.4) using a MWCO 3.5 kDa Spectra-Por dialysis membrane. The dialyzed supernatant was then sterilized by filtration through 0.2 μm membrane and kept frozen at −80° C. before G. lamblia inhibition assays.

[0159] Finally, biochemical nature of active molecules was determined by preincubating 5-fold concentrated bacterial supernatant obtained by ultrafiltration (>10 kDa) with different proteases coupled to beads. Briefly, proteinase K (Invitrogen) and pronase (Merck) were coupled to CNBr-activated Sepharose™ 4B (GE Healthcare) following manufacturer's instructions. Five milliliter of 5-fold concentrated bacterial supernatant or 5-fold concentrated fresh control medium were incubated for 6 h at room temperature in presence of 100 μl of packed beads previously coupled with 1 mg of each protease. Before growth inhibition assays, beads were removed by centrifugation (4,000×g 5 min). To assess proteases ability to digest proteins from bacterial supernatant, protein content before and after incubation with proteases, was estimated by SDS-PAGE after trichloroacetic acid (TCA) precipitation.

Measurement of Free Fatty Acids

[0160] To assess the presence of free fatty acids in the complex medium inducing Giardia growth inhibition, FCS, bile and LjLa1 supernatant (LjLa1sn) were analyzed for non-esterified fatty acids (NEFAs) content either alone (FCS, LjLa1sn, bile) or in combination (FCS-bile, FCS-LjLa1sn, bile-LjLa1sn, FCS-bile-LjLa1sn). Concentration of each component was that in the inhibition assay. Samples (0.5 ml) were prepared and kept on ice before being incubated for 24 h at 37° C. in the presence of 4.8×10.sup.4 trophozoites or without cells. At the end of the incubation period, tubes were chilled on ice, centrifuged at 700×g, 10 min at room temperature, then the supernatant was taken and frozen at −80° C. before NEFAs measurement. Numbers of living and dead trophozoites were determined using a Malassez cell chamber. NEFAs were quantified by using the NEFA-C kit, following manufacturer's instructions. Oleic acid was used as standard and NEFAs were expressed as oleic acid equivalents (Eq).

Bile Salt Hydrolase Activity Assays

[0161] After gel filtration, the eluted fractions were concentrated 10-fold by dialysis against 20 mM ammonium acetate buffer containing 2 M sucrose, pH 6.0, using a 3.5 kDa MWCO membrane (Spectrum Laboratories). Glycodeoxycholate (GDC) was used to perform growth inhibition assays and enzymatic assays. BSH activity was monitored by measuring glycine liberation from conjugated bile salt, following the protocol described by Grill et al., (2000). Briefly 100 μl of effluent fractions or BSH 1 unit or elution buffer were mixed with 100 μl of 2.4 g/l of GDC and incubated 24 h at 37° C. Controls were performed in the absence of bile salt or by pre-incubating effluent fractions with 2 mM iodoacetic acid or 30 min at 37° C. To stop the enzymatic reaction, an equal volume of 15% TCA (200 μl) was added and proteins were precipitated by centrifugation at 20,000 g for 15 minutes. 680 μl of 0.3M borate buffer, 1% SDS, pH 9.5 and 80 μl of 0.3% picrylsulfonic acid solution (Sigma) were added to 80 μl of supernatants. Mixtures were incubated for 30 min in the dark and 800 μl of 1 mM HCl were added to stop the reaction. Glycine concentration was measured at 416 nm using an Uvikon spectrophotometer 930 (Kontron Instruments). Standard curve was established with free glycine.

LC/ESI-MS Analysis of Modifications of Bile Components by LjLa1 Supernatants

[0162] 125 μl of bile-containing culture media of G. lamblia (KM, pH 6.0, with 2 g/L bovine bile) and 125 μl of LjLa1 supernatants prepared from a bacterial culture in KM medium supplemented with 10% fetal bovine serum, adjusted at pH 6.0 were mixed and incubated overnight at 37° C. Two different bile batches (B1 and B2) and two different bacterial supernatants (S1 and S2) were tested. The samples were diluted 4-fold in Milli-Q water and subjected to solid-phase extraction (SPE) using Oasis® HLB cartridges (30 mg solid phase). After conditioning with 3 ml methanol and 3 ml Milli-Q water, the cartridges were loaded with 1 ml of 4-fold diluted sample, washed with 2 ml Milli-Q water and eluted with 2 ml methanol. The eluted fractions were dried under vacuum and resuspended in 500 μl Milli-Q water/acetonitrile 90:10 (v/v). Five μl of each resuspended sample was analyzed by LC/ESI-MS on a Ultimate U3000 chomatographic system (Thermo) connected to a Q-STAR Pulsar Qq-TOF mass spectrometer equipped with an ionspray source (AB Sciex). The LC separation was achieved on a Interchrom Strategy C18-2 micro column (5 μm, 150×1 mm, 100 Å, Interchim). The elution gradient was 10% mobile phase B (acetonitrile) to 70% B against mobile phase A (5 mM ammonium formate/formic acid, pH 6) over 45 min, at a flow rate of 40 μl/min. The MS data were acquired in negative mode, in the range m/z 250-1200. Each LC/ESI-MS experiment was conducted twice. Data-dependant LC/ESI-MS/MS experiments were also conducted on each sample, alternating 1-second full-scan MS followed by two 2-second product ion collision induced dissociation (CID) of the major ions detected at the first step, using a −50 V collision voltage. Each raw LC/ESI-MS data was converted into Network Commun Data Form (NetCDF) using the translation tool provided by AB Sciex. The data were processed with XCMS (Smith et al. 2006), a software implemented in the freely available R environment (www.r-project.org), which allows automatic retention time alignment, matched filtration, peak detection and peak matching.

Protein Precipitation

[0163] 0.1% of sodium lauroyl sarcosinate (NLS, Sigma) was added to bacterial supernatants. After mixing, TCA (trichloroacetic acid) was added to a final 7.5% concentration, and the solution was precipitated on ice overnight. The mixed protein-detergent precipitate was collected by centrifugation (10,000×g, 10 min, 4° C.). The supernatant was carefully removed and the pellet washed twice with 2 ml of precooled tetrahydrofuran (Sigma). Finally, the pellet was dissolved in 0.4 ml extraction solution (7 M Urea, 2 M Thiourea, 4% CHAPS, 5 mM Tris(carboxyethyl)phosphine) (Rabilloud et al., 2009).

Proteomic Analysis of LjLa1 Supernatant

[0164] TCA precipitated LjLa1 supernatant was resuspended in 8 M urea in 20 mM TEAB (triethylammonium bicarbonate) and incubated for 1 h at room temperature (RT) with 20 mM DTT (Dithiothreitol), then with 50 mM IAA (iodacetamide) and incubated for a further hour at RT in the dark. The sample was incubated with 0.05 UA of endoproteinase Lys-C (Wako Pure Chemical Industries, Osaka, Japan) for 18 h at RT. Trypsin (Promega) digestion was performed with 2 μg of enzyme during 4 h at RT and terminated with TFA (trifluoroacetic acid), final concentration of 0.5%. The sample was passed sequentially through two home-made Poros Oligo-R3 (PerSeptive Biosystems, Framingham, USA) microcolumns packed (±1 cm) on p200 tips over 3 MM C18 material plug. Loaded resin was washed with 100 μl 0.1% TFA and peptides were eluted with 100 μl 70% acetonitrile (ACN)/0.1% TFA, then 20 μl 100% ACN. The sample was desalted, dried down, resuspended in 50% ACN and 10% was collected to amino acid analysis using a Biochrom 30 amino acid analyzer (Biochrom, Cambridge, U.K.), then dried and stored at −80° C. again until analysis.

[0165] Samples (3 μg per run) were analyzed by an EASY-nano LC system (Proxeon Biosystems, Odense, Denmark) coupled online to an LTQ-Orbitrap Velos mass spectrometer (Thermo Scientific, Waltham, USA). Peptides were loaded onto a 18 cm fused silica emitter 75 μl in inner diameter) packed in-house with reverse phase capillary column ReproSil-Pur C18-AQ 3 μm resin (Dr. Maisch GmbH, Germany) and eluted using a gradient from 100% phase A (0.1% formic acid) to 35% phase B (0.1% formic acid, 95% acetonitrile) for 180 min, 35% to 100% phase B for 5 min and 100% phase B for 8 min (a total of 23 min at 250 nl/min). After each run, the column was washed with 90% phase Band re-equilibrated with phase A. Mass spectra were acquired in positive mode applying data-dependent automatic survey MS scan and tandem mass spectra (MS/MS) acquisition. Each MS scan in the orbitrap (mass range of m/z of 400-1800 and resolution 100,000) was followed by MS/MS of the fifteen most intense ions in the LTQ. Fragmentation in the LTQ was performed by collision-induced dissociation and selected sequenced ions were dynamically excluded for 25 s. Raw data were viewed in Xcalibur v.2.1 (Thermo Scientific, Waltham, USA) and data processing was performed using Proteome Discoverer v.1.3 (Thermo Scientific, Waltham, USA). Generated raw files were submitted to searching using Proteome Discoverer with an in house Mascot v.2.3 algorithm against database of proteins predicted from the L. johnsonii isolates NCC533 and FI9785 and the L. johnsonii prophage Lj965. Contaminant proteins (several types of human keratins, BSA and porcine trypsin) were also added to the database and all contaminant proteins identified were manually removed from the result lists. The searches were performed with the following parameters: ms accuracy 10 ppm, MS/MS accuracy 0.6 Da, trypsin digestion with one missed cleavage allowed, fixed carbamidomethyl modification of cysteine and variable modification of oxidized methionine and N-terminal protein acetylation. Number of proteins, protein groups and number of peptides were filtered for False Discovery Rates (FDR) less than 1% and only peptides with rank 1 and minimal of 2 peptides per proteins were accepted for identification using Proteome Discoverer (Charneau et al., 2007); Queiroz et al. 2013).

Example 2: L. johnsonii La1 Supernatant Inhibitory Effect is Dependent Upon Bovine Bile and More Specifically Upon Bile Salts

[0166] Most media previously described to support G. lamblia growth commonly contains bile as a supply for parasite cholesterol and fatty acids requirements (Farthing et al., 1985, Gillin et al., 1986, Halliday et al., 1995).

[0167] In our hands, G. lamblia trophozoites growth can be observed in a common medium (KM-FCS) in the absence of bovine bile. Moreover, recommended bile concentrations (0.75 mg/ml, Perez et al., 2001) appeared to affect trophozoites growth when added to the common KM-FCS (FIG. 1A). Interestingly, LjLa1 inhibitory effect was observed only in presence of bile. No inhibitory effect by the supernatant could be observed in the absence of bovine bile, even after 24 h of culture (FIG. 1A). In presence of 0.75 g/L of bovine bile (Perez et al., 2001), G. lamblia trophozoites growth was slightly impacted by bacterial supernatant after 10 hours of contact but largely affected after 24 hours of contact (9.Math.10.sup.4 and 1.Math.10.sup.4 trophozoite/ml, respectively, FIG. 1A). Thus, the 24 h incubation time-period was retained for all subsequent inhibitory growth assays.

[0168] Maximum inhibitory effects of LjLa1 supernatant on parasite growth was observed either in the presence of 0.6 g/L complete bovine bile or in the presence of 0.032 g/L bile salts (96.3% and 75% of inhibition, respectively, by comparison with controls containing similar amount of lactic acid and bile or bile salts, FIG. 1B). Similar effects were observed using two isolates of G. lamblia (WB and HP1), two different commercial origins of bovine bile and two different media compatible with bacteria and parasite growth: MTYI (Perez et al., 2001) and KM-10% FCS (Data not shown). Subsequent inhibition in vitro assays were thus performed using 0.6 g/L of bovine bile.

Example 3: Characterization of the Inhibitory Activity

[0169] To biochemically characterize the inhibitory compounds present in the LjLa1 supernatant, this supernatant was treated with immobilized enzymes prior to contact with parasites. Parasite growth inhibition was abolished by proteinase K and pronase treatments of the supernatant, suggesting involvement of inhibitory factor(s) of peptidic nature (FIG. 2A). Heat-treatment also led to inactivation of the inhibitory properties of the bacterial supernatant (FIG. 2A). Additionally, in a pH range similar to the ones experienced by G. lamblia in vivo (Biagini et al., 2001), a strong influence of pH on the inhibitory reaction was noticed, with highest inhibition occurring at pH 6.2 (FIG. 2B).

[0170] Moreover, as Pridmore et al. (2004) demonstrated that the LjLa1 anti-Salmonella activity is mediated by the toxic hydrogen peroxide molecule H.sub.2O.sub.2 and can be abolished by a pretreatment with catalase, we checked whether treatment of LjLa1 supernatant with catalase might prevent its anti-Giardia effect. As it can be seen in FIG. 2A, catalase pretreatment only slightly affected the inhibitory activity of the LjLa1 supernatant on G. lamblia (FIG. 2A), invalidating the role of H.sub.2O.sub.2 in Giardia growth inhibition.

Example 4: Giardia Growth Inhibition by LjLa1 Supernatant is not Clue to Free Fatty Acids

[0171] To assess whether G. lamblia growth inhibition by LjLa1 supernatant might be due to toxic free fatty acids as demonstrated in previous reports (Rohrer et al. 1986), FCS, bile and LjLa1 supernatant were analyzed for non-esterified fatty acids (NEFAs) content either alone or in combination, using the NEFA-C methodology (WAKO diagnostics). The different samples were incubated for 24 h at 37° C. with or without G. lamblia trophozoites and the cell supernatants were analyzed for NEFAs. Survival and growth of the parasites in those different conditions were determined.

[0172] The following Table 1 represents the analysis of non-esterified fatty acids involvement in Giardia inhibition. The different components of the Giardia culture medium (FCS 10% and/or bile 0.5 g/L), as well as LjLa1sn, were analyzed either alone or in combination for NEFA content after 24 h of incubation at 37° C. Incubation was performed with or without G. lamblia trophozoites (9.6×10.sup.4/ml). Survival and multiplication of G. lamblia after 24 h in those different media were determined. Parasite multiplication was expressed as the number of total trophozoites after 24 h of incubation/number of trophozoites at time zero of incubation (i.e. multiplication factor). Trophozoite survival rate after 24 h of incubation was expressed as the (number of living cells/total number of cells)×100. ±SD (triplicate).

[0173] Supernatants with FCS, LjLa1sn or bile alone displayed NEFAs concentrations of 40.9, 36.3 and 4.5 μM, respectively (Table 1).

TABLE-US-00001 TABLE 1 NEFAs Multiplication Survival rate Incubation medium (μM Eq) factor (%) KM 0 1.1 14.3 KM + FCS 40.9 3.3 89.8 KM + bile 4.5 0.7 0 KM + LjLa1sn 36.4 1.2 71.6 KM + FCS + bile 95.4 2.3 93.8 KM + FCS + LjLa1sn 68.2 2.1 87.5 KM + bile + LjLa1sn 50.0 0.8 0 KM + FCS + bile + LjLa1sn 140.9 0.8 0

[0174] The amount of NEFAs was doubled (95.4 μM) by co-incubation of the bile with serum suggesting enzymatic release of NEFAs. However, equal amounts were found at time zero and time 24 h of the co-incubation (not shown), indicating that fatty acids were not released in a time-dependent manner. It was hypothesized that the high amount of NEFAs might result from a detergent-like action of the bile on serum lipids, possibly improving accessibility of NEFAs to the NEFA-C kit reagents. The highest amount of NEFAs (140.9 μM) was measured upon co-incubation of FCS with bile and LjLa1sn, as could be expected by summing their respective NEFAs contents. Incubation with G. lamblia had no noticeable effect on the NEFA content of the various samples (Data not shown).

[0175] Normal growth of G. lamblia (multiplication factor: 3.34, Table 1) was observed in the presence of 10% FCS alone. Trophozoites did not survive in KM medium containing only bile, whereas most of them (˜70%) were still alive although they did not develop when incubated in KM with LjLa1 supernatant, most probably due to the low concentration of FCS in LjLa1 supernatant. Remarkably, trophozoites survival was abolished upon addition of bile to LjLa1 sn although the same concentration of FCS is present, indicating the presence of inhibitory elements. By comparing NEFAs contents of the different media, it appeared that NEFAs could hardly be responsible for parasite death. Indeed, more NEFAs were found in the KM+FCS+bile or KM+FCS+LjLa1sn media (95.4 and 68.2 μM of NEFAs respectively), which allowed parasite survival, than in the KM+bile+LjLa1sn medium (50.0 μM of NEFAs) which induced the death of all the parasites. This indicated that the concomitant addition of bile and bacterial supernatant rather than high level of NEFAs is lethal to Giardia and is responsible for the killing effect observed in the presence of FCS, bile and LjLa1 supernatant.

Example 5: Characterization of LjLa1 Supernatant Inhibitory Activity

The LjLa1 Supernatant Inhibitory Activity is Due to ˜30 kDa Molar Mass Factor(s)

[0176] Fractionation experiments indicated that the inhibitory activity in LjLa1 supernatant was due to molecule(s) bigger than 10 kDa, since fraction >10 showed a high G. lamblia inhibitory activity compared to the fraction <10 kDa (FIG. 2C). By performing a 30 kDa threshold fractionation, we found that the inhibitory activity concentrated mostly in the >30 kDa fraction (inducing 66% of Giardia growth inhibition, FIG. 2C), however moderate inhibitory effect (˜40%) was also observed with the <30 kDa fraction, which led us to propose that the molar mass(es) of the active molecule(s) are close to this threshold. In good accordance with this, 50 kDa threshold fractionation of the LjLa1sn was unable to segregate the inhibitory activity, i.e. 50% and 48% of Giardia growth inhibition were induced by the <50 kDa and >50 kDa fractions, respectively (FIG. 2C), indicating that inhibitory protein(s) molar mass is smaller than 50 kDa.

Small Compounds are not Primarily Involved in LjLa1sn Inhibitory Activity

[0177] It has been reported that molecule(s) smaller than 1 kDa (Perez et al., 2001) would be involved in the giardiacidal activity of the LjLa1 supernatant, in contradiction with our findings of a ≧30 kDa molecule(s). The possibility that dialysis against GKN buffer as used in Perez's report might somehow inhibit the activity has been checked. Several points were checked. At first, because the pH of the GKN buffer is 7.4 and the LjLa1sn inhibitory activity is inactivated at pH above 7.0 (FIG. 2B), pH of the KM medium was checked after supplementation with 10% FCS and 25% GKN. The pH was found to be increased to 6.5, hence not expected to inactivate LjLa1 supernatant (FIG. 2B). Second, to assess whether small component(s) might be involved in the inhibitory effect, the bacterial supernatant was dialyzed using a 3.5 kDa molecular weight cut-off membrane against both KM 10% FCS and GKN buffer. As can be seen in the following Table 2, parasite killing activity of the LjLa1 supernatant in the presence of bile was fully recovered after dialysis, whatever the dialysis solution. Table 2 represents dialysis through low MW cutoff membrane does not inactivate inhibitory activity of LjLa1 supernatant (LjLa1sn). KM-FCS medium, bile (0.5 g/L) and LjLa1sn, either alone or in combination, were dialyzed against GKN buffer or KM-FCS, and then tested for G. lamblia trophozoites growth. Values are mean of two independent experiments performed in duplicate.

TABLE-US-00002 TABLE 2 KM + FCS + KM + FCS + LjLa1sn LjLa1sn KM + FCS + KM + FCS + dialysed against dialysed against KM + FCS GKN LjLa1sn KM-FCS GKN Multiplication 3.82 2.60 3.24 3.68 2.44 factor Survival 93.7 92.3 88.3 90.2 89.3 rate (%) KM + FCS + KM + FCS + bile + LjLa1sn bile + LjLa1sn KM + FCS + KM + FCS + dialysed against dialysed against bile bile + LjLa1sn KM-FCS GKN Multiplication 2.28 1.16 1.46 0.8 factor Survival 92.9 0 0 0 rate (%)

[0178] This indicates on one side that no element crucial to activity is lost upon dialysis and on the other side that the GKN buffer is not inhibitory to the LjLa1 supernatant activity. Also, it can be noticed from Table 2 that addition of 25% GKN buffer to KM-FCS does not affect parasite survival but slows down its development (multiplication rate of 2.60 in the presence of GKN versus 3.82 in the absence of GKN).

Example 6: Impact of LjLa1 Supernatant on Bile Composition

[0179] Since concomitant addition of bile and LjLa1sn to the culture medium leads to inhibition of G. lamblia growth, we assessed whether bile composition might be modified by LjLa1 supernatant. Bile composition after 24 h of incubation with LjLa1sn was investigated by mass spectrometry (FIGS. 3A-B). Impacted molecules were identified by their MS/MS fragmentation pattern. Comparison of bile salts profiles showed a decrease of conjugated salts (GC, TC, GDC, TDC, GCDC, TCDC) in favor of non-conjugated salts. Cholate and desoxycholate were the mainly statistically enhanced non-conjugated salts when bile was incubated with LjLa1 supernatant (FIG. 4) and in a minor proportion chenodesoxycholate. These modifications were not observed in presence of heat-treated bacterial supernatant (FIG. 3C).

Example 7: Impact of Deconjugated Bile Salts on G. lamblia Trophozoites Growth

[0180] The inhibitory effects toward G. lamblia growth of pure bile salts (cholate, desoxycholate and chenodesoxycholate) conjugated to glycine or taurine, or their deconjugated counterparts were investigated in the presence or the absence of LjLa1 supernatant (Table 3, FIG. 5). In the absence of LjLa1sn, glycyl- or tauryl-conjugated salts as well as deconjugated cholate showed no apparent toxicity at the concentrations tested (IC.sub.50 values>500 μM). In contrast, the deconjugated salts DC and CDC exhibited inhibitory effects on trophozoites growth with IC.sub.50 values of 132 μM (DC) and 147 μM (CDC) respectively. Interestingly, in the presence of LjLa1 supernatant, the conjugated bile salts IC.sub.50 values felt to a range of values similar to those measured for their pure deconjugated counterparts, i.e. 104 μM (GDC), 79 μM (TDC), 110 μM (GCDC) and 115 μM (TCDC) (Table 3 and FIG. 5).

[0181] The following table 3 shows conjugated bile salts in association with LjLa1 supernatant (LjLa1sn) as well as deconjugated bile salts prevent the growth of G. lamblia. Various concentrations of taurine- and glycine-conjugated and unconjugated C, DC and CDC bile salts were tested for G. lamblia trophozoites growth inhibition in KM-FCS in the presence or absence of LjLa1sn (bacterial spent culture medium). IC50 values were determined from drug-response curves and expressed as mean+/−SD of at least three independent experiments.

TABLE-US-00003 TABLE 3 With culture With bacterial spent medium only culture medium IC50 +/− SD (μM) IC50 +/− SD (μM) C and C Cholate >400 >400 derivatives GC Glycocholate >400 >400 TC Taurocholate >400 >400 DC and DC Desoxycholate 132 +/− 12.7 117 +/− 12.7 derivatives GDC Glycodesoxycholate >400 104 +/− 12.7 TDC Taurodesoxycholate >400  79 +/− 17.3 CDC and CDC Chenodesoxycholate 147 +/− 14.5 118 +/− 21.7 derivatives GCDC Glycochenodesoxycholate >400 110 +/− 10.6 TCDC Taurochenodesoxycholate >400 115 +/− 7.7  FA Fusidic acid 26 +/− 3.7 nd

[0182] These results suggested that a deconjugating process mediated by LjLa1sn component(s) and producing deconjugated bile salts might be responsible for the inhibitory effect of the association of bile and LjLa1sn. Such hypothesis is in line with the previous observation that fusidic acid, an antibiotic with a bile salt-like chemical structure is toxic to Giardia (see Table 3, IC.sub.50 value=26 μM) unless conjugated to taurine or glycine (Farthing et al., 1986).

Example 8: Potential Involvement of L. Johnsonii La1 Bile-Salt Hydrolase(s) in Bile-Mediated Giardia Inhibition, and Co-Elution of BSH-Like Activity and Giardia Inhibitory Activity in Size Fractionation Chromatography of LjLa1 Supernatant

[0183] It is known that bile salt deconjugating process is mediated by 3-alpha, 7-alpha, 12-alpha-trihydroxy-5-beta-cholan-24-oylglycine/taurine amidohydrolases (EC 3.5.1.24), also named choloylglycine/taurine hydrolases or conjugated bile acid hydrolases (CBAH) or bile salt hydrolases (BSH). These enzymes act on carbon-nitrogen bonds other than peptide bonds, specifically in linear amides, releasing glycine and taurine from conjugated bile salts. In L. johnsonii genome, three genes encoding BSH-like enzymes have been predicted (LJ0056 (BSH-56), LJ1147 (BSH-47) and LJ1412 (BSH-12) genes). They are also predicted as secreted proteins by SecretomeP, with theoretical full sizes of 34.9 kDa, 36.3 kDa and 36.6 kDa and secreted sizes of 29.8 kDa, 31.0 kDa and 31.3 kDa (data not shown).

[0184] To test the hypothesis of bacterial BSH(s) involvement in G. lamblia growth inhibitory activity by LjLa1sn, the bacterial supernatant was fractionated by gel filtration chromatography on Sephacryl S300 column 16/100, and eluted fractions were assayed for parasite inhibition and bile salt deconjugating activity.

[0185] A typical elution profile is shown in FIG. 5A. Twelve eluated fractions (FIG. 5A) were tested for G. lamblia growth inhibition (FIG. 5C) and the most active ones were further tested for BSH-like activity (FIG. 5B). Greatest inhibitory activity was recovered from fractions containing proteins with molecular weight between 13.7 kDa and 67 kDa (FIG. 5A). Those fractions exhibited BSH-like activity (FIG. 5C), as measured by the release of glycine from GDCA. In our experimental conditions, 1 unit of the commercial Clostridium perfringens BSH induced the release of 0.76 mM glycine from 2.5 mM GDC within 24 hours. Concomitant elution of inhibitory and BSH activities within similar molecular weight range was observed with LjLa1 supernatants from different culture batches. Our attempts to further purify elements responsible for inhibitory activity and/or BSH-like activity by combining steps of ion-exchange chromatography, hydrophobic interaction chromatography and chromatofocusing were unsuccessful, with a rapid loss of the activities.

Example 9: Deconjugation of Tauryl- and Glycyl-DC and -CDC by Clostridium perfringens BSH is Toxic to G. lamblia

[0186] To assess capability of BSH enzymes to promote bile-mediated anti-Giardia effect, BSH from the bacteria C. perfringens was tested for G. lamblia growth inhibition in the presence of bile or pure conjugated bile salts. As noted above (Table 3), the glycine or taurine conjugated bile salts, TDC, TCDC, GDC and GCDC have no inhibitory activity on G. lamblia growth in KM-FCS culture medium. In contrast, the addition of 2 units of C. perfringens BSH to the culture in the presence of those bile salts led to a remarkable parasite growth inhibition within the 24 h of the assay, with inhibition ranges of 95 to 100%, depending upon the conjugated bile salt tested (FIG. 6). Heat inactivation of bacterial BSH (100° C., 5 min) before its addition to the parasite culture led to a dramatic fall of its anti-Giardia activity (less than 10% growth inhibition depending upon the conjugated bile salts tested, FIG. 6) indicating that BSH inhibitory activity depends on its enzymatic activity.

Example 10: Mass Spectrometric Identification of Two BSH-Like Enzymes in the LjLa1sn

[0187] It was then searched whether BSH-like enzymes annotated from L. johnsonii La1 genome, and predicted by SecretomeP to be secreted, are indeed released in the extracellular medium. High-resolution mass spectrometry-based proteomic analysis of the LjLa1 extracellular proteins was performed. 3 μg of proteins of LjLa1 supernatants from two independent culture replicates allowed identification of over a hundred of secreted protein groups (data not shown). Amongst them, two of the three predicted BSH were clearly identified in both replicates: LJ1412 (gi|41583570) and LJ1147 (gi|41583360). The following Table 4 shows the identification of two conjugated bile salt hydrolases of Lactobacillus johnsonii NCC533 by MS/MS peptide fragmentation using MASCOT stringent search.

TABLE-US-00004 TABLE 4 Peptide ion sequence.sup.d (with pep- unique total at least one tide Theo. Accession Cov. pep- pep- peptide ion ion Mass Theo. number.sup.a Score.sup.b (%).sup.c tides tides PSMs score > 50 charge.sup.e (m/z) (kDa).sup.f pI.sup.g experimental replicate 1 gi|41583570 162 12.58 2 2 5 NLANYSNIAPAQPK 2 750.9 36.6 5.2 AHSPQGNNELSSVT 4 759.1 NYFHILHSVEQPK gi|41583360  39 12.92 3 3 3 GLGIAGLNFTGPGK 2 651.4 36.3 4.9 DLPVTTLHWLMGDK 2 813.4 NTLVPNADINLYSR 2 795.4 experimental replicate 2 gi|41583570  83 12.58 2 2 3 NLANYSNIAPAQPK 2 750.9 36.6 5.2 AHSPQGNNELSSVT 4 759.1 NYFHILHSVEQPK gi|41583360  77  8.62 2 2 3 GLGIAGLNFTGPGK 2 651.4 36.3 4.9 NTLVPNADINLYSR 2 795.4 .sup.aAccession number in the NCBI protein database. All accession numbers refer to sequences from Lactobacillus johnsonii NCC 533; .sup.bProbability-based Mowse score of MASCOT software that evaluates if the peptides subjected to search are the same as those found in the database originated by in silico digestion of a known protein; .sup.cCoverage is the percentage of predicted protein sequence covered by matched peptides via MASCOT; .sup.dPeptide sequences identified via MASCOT following the experimental peptide masses after parental ion fragmentation. It was required that at least one spectrum should be matched with score of 50 or better to considered the hit. .sup.eDoubly- to quintuply-charged ions of selected peptides were analyzed. .sup.fTheoretical molecular masses of proteins calculated from amino acid sequences; .sup.gTheoretical isoelectric points of proteins calculated from amino acid sequences;

Example 11: Measurement of G. lamblia Inhibition by Flow Cytometry

[0188] The inhibitory effect of L. johnsonnii on G. lamblia was measured by flow cytometry, as shown in FIGS. 7A to 7E. Propidium iodide, an intercalating agent fluorescing when excited at 540 nm, was used to evaluate Giardia cell viability in order to confirm Hemocytometer results. These results showed that, tested separately, neither LjLa1sn nor bovine bile (0.6 g/L) have cell lysis activity. However, in presence of both Ljla1sn and bovine there is a fluorescence shift (FIG. 7E) evincing that bile has a cytotoxic effect on Giardia trophozoites (FIG. 7D;FIG. 7E). Flow cytometry allowed us to analyse a higher amount of cells and may be used routinely as a measurement method of G. lamblia inhibition. Moreover, this technique has been used for other lactobacilli supernatant (data not shown).

Example 12: Identification of Anti-Giardiasis Lactobacilli Strains

[0189] The inhibitory effect on G. lamblia growth of different lactobacilli strains was screened (cf. table 5). Bacterial supernatant was co-incubated for 24 h at 37° C. with Giardia trophozoite cultures (triplicates), with or without bovine bile (0.6 g/L). Different species of lactobacilli were identified as potent inhibitors of Giardia lamblia growth, as Lactobacillus johnsonii, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus reuteri. 14 lactobacilli strains showed significant inhibitory effects (ANOVA statistic tests) in presence of bile (FIG. 8) None of the supernatant had an inhibitory effect without bovine bile, confirming that the giardiacidal effect is bile dependent. Table 5 indicates the corresponding internal and official references of the bacterial strains, and bibliographic references.

TABLE-US-00005 TABLE 5 Official reference Bacterial strain ATCC CIP (*) LMG (*) CNCM (*) Publication L. johnsonii I-4885 Fujisawa et al., 1992 L. gasseri 33323 102991 9203 T Lauer and Kandler, 1980 L. johnsonii 103614 Fujisawa et al., 1992 L. johnsonii 103786 Fujisawa et al., 1992 L. johnsonii 33200 103620 9436 T Fujisawa et al., 1992 L. johnsonii 332 103652 11468 Fujisawa et al., 1992 L. johnsonii 11506 103653 9437 Fujisawa et al., 1992 L. johnsonii 103654 Fujisawa et al., 1992 L. johnsonii 103781 Fujisawa et al., 1992 L. johnsonii 103782 Fujisawa et al., 1992 L. johnsonii La1 NCC533 Pridmore et al. (2004) L. gasseri 11413 L. gasseri 29601 11414 I-4884 L. acidophilus N 700396 FM (*) CIP: Collection de l'Institut Pasteur, France LMG: Laboratorium voor Microbiologie, Gent University, Belgium CNCM: Collection Nationale de Microorganismes, Institut Pasteur, France ATCC: American Type Tissue Collection, USA

Example 13: Heterologous Expression of LjLa1 BSH in E. coli

[0190] To study the properties of the LjLa1 BSHs, we cloned the BSH genes into a pStaby vector (StabyExpress, Delphigenetics) in order to purify BSHs using His-Tag system. E. coli expressions cells (E. coli SE, Delphigenetics) were then transformed The recombinant BSH-47 protein was produced in E. coli SE cells and purified using a His-Tag system (Sephadex Ni-NTA column, GE Healthcare). The activity of recombinant BSH-47 was tested using taurodeoxycholic (0.3%) and glycodeoxycholic (0.3%) LB agar (Chae et al 2013). After 48 h of incubation at 37° C., we observed that the recombinant BSH-47 is taurospecific (FIG. 9).

[0191] Furthermore, the effect of recombinant LjLa1 BSH-47 has been studied on Giardia trophozoïtes cultures, in the presence or not of bovine bile (0.06 g/L). The results show that recombinant BSH-47 (0.96 U, with “U” designing enzymatic units) exhibits an inhibiting effect, the level of this inhibiting effect is equivalent to the inhibiting effect of C. perfringens BSH (1 U) (FIG. 10).

Example 14: Characterization of the Inhibitory Activity of LjLa1 BSH-47 and BSH-56 In Vitro

[0192] The effects of recombinant LjLa1 BSH-47 and BSH-56 were studied on cultures of G. lamblia trophozoites in either presence or absence of bovine bile (0.06 g/L). Recombinant BSH-56 was produced according to the process described for the production of BSH-47, such as described in Example 13. Several BSH concentration were tested ranging from 0.0001 μg/ml to 10 μg/ml. Interestingly, both BSH-47 (FIG. 11A) and BSH-56 (FIG. 11B) exhibit strong inhibitory effects. These results are in agreement with those obtained with commercial C. perfringens BSH (Example 8) (FIG. 10). As expected, no inhibitory effect was observed without bovine bile.

Specific Activities:

[0193] Previous experiments allowed us to determine the substrate specificity of newly purified BSH-47 and BSH-56 and their specific activities had been determined. BSH-47 is able to deconjugate taurospecific bile salts while BSH-56 is able to deconjugate both taurospecific and glycospecific bile salts.

TABLE-US-00006 TABLE 6 Specific activity Specific activity (μmole of glycine/5 min (μmole taurine/5 min at 37° C./mg of protein) at 37° C./mg of protein) C. perfringens 0.690 0.150 BSH BSH-47 0.066 0.717 BSH-56 0.536 2.604

Example 15: In Vivo Effect of L. gasseri CNCM I-4884 Against G. lamblia

[0194] L. johnsonii La1 and L. gasseri CNCM I-4884 strains (L. gasseri CNCM I-4884 is also designated as L. gasseri ATCC29601 in FIG. 8 and in Table 5) were daily administered by intragastric gavage (5×10.sup.8 CFU) to neonatal mice from day 5 to day 15 (day of sacrifice). Mice were challenged with trophozoites at day 10 by intragastric gavage (1×10.sup.5 trophozoites) and then were sacrificed at day 15. Preliminary experiments allow us to determine that there is a peak in the Giardia infection rate 5 days postinoculation (data not shown). The presence of living trophozoites in the small intestine is a marker of Giardia infection. Mice were divided into three groups with a minimum of 8 animals per group. We observed a significant reduction (p<0.05) in the parasite load in the small intestine in groups treated with L. gasseri CNCM I-4884 compared to control animals administered with PBS (FIG. 12A). Interestingly, L. gasseri CNCM I-4884 was more efficient in reducing the number of trophozoites than L. johnsonii La1. In agreement with these observations, the counting of cysts in the large intestine showed a significant reduction (p<0.05) in groups treated with L. gasseri CNCM I-4884 compared to controls, whereas no significant reduction was observed in the group treated with L. johnsonii La1 (FIG. 12B).

Example 16: In Vivo Effect of BSH-47 Against G. lamblia

[0195] Solutions of recombinant BSH-47 solutions (1 μg/ml, 10 μg/ml and 100 μg/ml diluted in NaHCO3 16.4%) were thawed and daily administered by intragastric gavage to neonatal mice (dose were respectively 0.05 m, 0.5 μg and 5 μg per mice) from day 10 to day 15 (day of sacrifice). Control animals received PBS instead of BSH. All groups treated with BSH-47 showed a reduction in trophozoites load in the small intestine compared with the control (FIG. 13). However, only the group treated with 100 μg/ml of BSH-47 displayed significant reduction in the parasite load.

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