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R Lallier

Publications and source records attributed to R Lallier.

At least 19 recordsLinked to original sources
PubMed1992

Biochemical characterization of an antigenic saline extract of Actinobacillus pleuropneumoniae serotype 5 and identification of a serotype-specific antigen for ELISA serodiagnosis.

A saline extract of boiled-formalinized whole cells from a local strain (81-750; Quebec, Canada) of Actinobacillus pleuropneumoniae, serotype 5b was used as an antigen in an enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of swine pleuropneumonia. Characterization of this crude extract was done and proteins, neutral sugars, hexosamines, and 2-keto-3-deoxyoctonate (KDO) were evaluated. On phenol extraction of the crude extract a serotype-specific antigen of polysaccharidic nature was recovered from the aqueous phase. This antigen was characterized using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with Coomassie blue, silver and Schiff stainings. Immunoblots were done using sera of experimentally infected pigs that showed serotype specificity and cross-reactivity. Overall, the results indicate that the O-chain of lipopolysaccharides is a specific antigen that could be used in ELISA for the serodiagnosis of serotype 5 of A. pleuropneumoniae.

Actinobacillus Infections↗
PubMed1991

Production and purification of heat-stable enterotoxin b from a porcine Escherichia coli strain.

Production of heat-stable enterotoxin b (STb) by porcine Escherichia coli strains belonging to serogroup O115 was evaluated in ligated intestinal segments of adult rats. The conditions for optimal production and detection of STb were studied by using the STb-producing strain 4247. As STb production was similar in complex Trypticase soy broth and minimal Davis medium, the latter was used for the fermentation of strain 4247 and the production of STb in large quantities. STb was then purified to apparent homogeneity by sequential ultrafiltration, ultracentrifugation, and preparative gel electrophoresis. The enterotoxin was purified more than 500-fold and exhibited a molecular weight of approximately 5,000 as determined by urea-sodium dodecyl sulfate gel electrophoresis. Purified STb retained such chemical characteristics as resistance to heating (60 degrees C/30 min) and sensitivity to trypsin. A rabbit polyclonal antiserum was produced against the purified toxin. Numerous booster doses were required to obtain a significant enzyme-linked immunosorbent assay titer, suggesting that STb is a poor immunogen. Nevertheless, the antiserum was used successfully to discriminate between culture supernatants of STb-positive and STb-negative O115 E. coli strains, thus demonstrating the immunogenicity of purified STb.

Animals↗
PubMed1990

Immunoelectron microscopic demonstration that Renibacterium salmoninarum is encapsulated.

The cell surfaces of four strains of Renibacterium salmoninarum, including the type strain Lea-7-74T, were examined by transmission electron microscopy after immuno-stabilization and staining with ruthenium red. Cells were covered with a layer of capsular material whose thickness varied between 30 to 60 nm. Our results indicate that R. salmoninarum is encapsulated.

Animals↗
PubMed1990

Purification, and biochemical and structural characterization of a fimbrial haemagglutinin of Renibacterium salmoninarum.

Renibacterium salmoninarum was shown to possess peritrichous fimbriae. Electron microscopy of strains FMV 84-01 and ATCC 33209T revealed short, flexible fimbriae less than 2 nm in diameter. These surface appendages were isolated from the bacteria by a procedure involving water extraction and urea solubilization. The fimbrin was purified to homogeneity by Fast Pressure Liquid Chromatography, and shown by SDS-PAGE to be a protein of 57 kDa. Isoelectric focusing under non-denaturing conditions indicated a pI of 4.8. The protein had an amino acid composition rich in glycine, Asx (aspartic acid and asparagine), valine and alanine; methionine was absent. Approximately 33% of the amino acid residues were hydrophobic. Immunoblotting using a polyclonal antiserum raised against whole cells showed that the 57 kDa protein was the immunodominant antigen on the cell surface. Immunogold labelling using polyclonal antibodies raised against the fimbrin revealed an alignment of gold particles along the fimbriae. Purified fimbriae caused agglutination of rabbit erythrocytes and antifimbrial serum inhibited this haemagglutination. Altogether the results indicate that the fimbriae on the surface of R. salmoninarum are responsible for the haemagglutinating activity.

Amino Acids↗
PubMed1988

Biochemical and toxigenic characteristics of Aeromonas spp. isolated from diseased mammals, moribund and healthy fish.

In this study we describe biochemical, toxigenic and surface characteristics of 33 motile Aeromonas isolated from diseased mammals, 3 from moribund marine mammals, 24 from healthy fish and 4 from moribund fish. Aeromonas hydrophila, A. caviae and A. sobria were isolated from both mammals and fish but at a different incidence. Aeromonas hydrophila was the predominant species isolated from clinical specimens; it was isolated from pneumonia, wound infections, septicemia and abortion in horses, cattle and pigs. Aeromonas sobria was isolated from one mammal and 11 healthy fish. Aeromonas caviae was isolated in 2 cases from healthy fish and in 9 cases from diseased mammals. Variations in some biochemical tests including sorbitol, amylase and citrate, were observed between isolates from different sources. However, these differences did not allow the differentiation of isolates from diseased mammals and healthy fish. The majority of A. hydrophila isolates produced different extracellular products; A. sobria isolates produced less exotoxin. With A. caviae isolates no hemolysin, protease, enterotoxin or elastase were detected. There was no quantitative difference in hemolysin, protease, enterotoxin or elastase production between isolates from mammals and fish. It is suggested that A. hydrophila could be a potential pathogen for domestic animals, and fish may represent a potential reservoir of infection.

Aeromonas↗
PubMed1986

Surface antigens of virulent strains of Aeromonas hydrophila.

Antiserum was raised in rabbits to whole cells of a representative strain from a group of A. hydrophila strains exhibiting enhanced virulence for fish. The major surface antigens of the strain were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. The lipopolysaccharide (LPS) was examined using SDS-PAGE and silver staining. It was found to possess O polysaccharide chains of homogeneous length that were highly immunogenic. The LPS was conserved both morphologically and antigenically throughout the high virulence group. Heat-labile protein antigens were detected after absorption of the antiserum with boiled cells of the homologous strain. Only one major protein antigen, with a molecular weight of approximately 52,000, was present in outer membrane preparations or in whole cell lysates. A representative strain from the high virulence group, strain TF7, was shown by electron microscopy to be covered by a regular surface protein array (S-layer) which was found to be composed primarily of the 52 KD protein antigen. All the other members of the A. hydrophila high virulence group were shown to possess similar S-layers.

Aeromonas↗
PubMed1986

New fimbrial antigen F165 from Escherichia coli serogroup O115 strains isolated from piglets with diarrhea.

Sixteen strains of Escherichia coli serogroup O115 isolated from piglets with diarrhea were examined for mannose-sensitive or mannose-resistant hemagglutination (MSHA or MRHA, respectively) for the presence of fimbriae by electron microscopy and for enterotoxigenicity by the ligated gut loop technique in 10-day-old piglets. Four strains demonstrated MRHA of sheep, goat, pig, dog, cat, chicken, and human erythrocytes but no MRHA of calf, horse, guinea pig, and rabbit erythrocytes. They were divided into pattern I (MSHA negative) and pattern II (MSHA positive). The remaining 12 strains were classified as pattern III (MRHA negative, MSHA positive) and pattern IV (hemagglutination negative). An antiserum produced against the MRHA-positive, MSHA-negative strain 4787 and absorbed by the same strain grown at 15 degrees C agglutinated all of the MRHA-positive strains but none of the MRHA-negative strains and completely inhibited the MRHA of these strains. The surface antigen against which this absorbed antiserum was directed was designated "F165." Fimbriae (pili) purified from strain 4787 hemagglutinated erythrocytes in the same mannose-resistant pattern as the strain itself and reacted with the anti-F165 antiserum in an enzyme-linked immunosorbent assay, thus demonstrating the fimbrial nature of the hemagglutinating F165 antigen. The F165 antigen showed no serological relationship with the fimbrial antigens F4, F5, F6, and "F41". A positive correlation between the presence of F165 and the lack of enterotoxigenicity was demonstrated. Thus, we found a new mannose-resistant, hemagglutinating fimbrial antigen, F165, which is produced only by nonenterotoxigenic strains of E. coli serogroup O115. The possible role of F165 as a virulence attribute of E. coli strains causing extraintestinal disease is discussed.

Adhesiveness↗
PubMed1985

Immunity to Aeromonas salmonicida in coho salmon (Oncorhynchus kisutch) induced by modified Freund's complete adjuvant: its non-specific nature and the probable role of macrophages in the phenomenon.

Juvenile coho salmon (Oncorhynchus kisutch), vaccinated with one intraperitoneal injection of formalin-killed virulent Aeromonas salmonicida cells suspended in saline, showed increased protection against approximately one LD60 of homologous challenge administered at 30 days post-vaccination. Under similar conditions, coho vaccinated with a modified complete Freund's adjuvant (MFCA) alone were also equally protected. When measured against a more severe A. salmonicida challenge of approximately one LD95, the strength of the MFCA-induced protection was found to exceed that produced by the homologous bacterin administered in saline or incomplete adjuvant, and the protection was still evident at 90 days post-treatment. Other more precise measurements indicated the LD50 for MFCA-treated coho to be up to 450 times that for saline-treated coho. Two other tested adjuvants, levamisole and MDP (N-acetyl-muramyl-L-alanyl-D-isoglutamine), administered in a modified Freund's incomplete adjuvant, also enhanced anti-A. salmonicida immunity but to a lesser degree. The active factor in MFCA was a killed Mycobacterium butyricum preparation, and the anti-A. salmonicida immunity it induced was non-specific because the immunity extended to two other serologically distinct fish pathogens tested: A. hydrophila (LD50 increase of 5.3-fold) and Vibrio ordalii (LD50 increase of 560-fold). Macrophages are believed to account for the M. butyricum-induced anti-A. salmonicida immunity because the immunity was a) non-specific, b) very rapid in onset (it was measurable by 4 days), and c) influenced by particulate preparations, known to affect macrophage function and immunity in mammals. The possible benefits of adjuvant-induced non-specific immunity in cultured fish are discussed.

Aeromonas↗
PubMed1985

Electrophoretic and immunochemical analyses of the lipopolysaccharides from various strains of Aeromonas hydrophila.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to analyze the lipopolysaccharides isolated from strains of Aeromonas hydrophila which exhibit virulence for fish and which autoaggregate during growth in static broth culture. The lipopolysaccharides contained O-polysaccharide chains of homogeneous chain length. Two of the strains produced a surface protein array, and immunofluorescence and phage-binding studies revealed that a number of these O-polysaccharide chains of homogeneous length traversed the protein array and were exposed on the cell surface. Immunochemical analyses by immunoblotting, enzyme-linked immunosorbent assay, immunofluorescence, and immunoprecipitation with both polyclonal and monoclonal antibodies revealed the presence of three epitopes on the polysaccharide moiety of this homogenous-chain-length lipopolysaccharide morphotype. One epitope was species serogroup specific and reactive by immunoblotting. This epitope was not present on the heterogeneous-chain-length O polysaccharides of nonautoaggregating strains of A. hydrophila examined. The second epitope was conformation dependent and cross-reactive with an epitope on the homogenous-chain-length O polysaccharides of Aeromonas salmonicida lipopolysaccharide. The third epitope was recognized by a monoclonal antibody and appeared to involve that region of the A. hydrophila and A. salmonicida lipopolysaccharide molecules which contained the O-polysaccharide-core oligosaccharide glycosidic linkage.

Adsorption↗
PubMed1979

Binding of Salmonella minnesota R-form glycolipid mR595 to rat fibroblasts and its effect on cell metabolism and cell behaviour.

Trypsinized normal rat embryo fibroblasts and untrypsinized and trypsinized transformed rat fibroblasts have two orders of binding sites for bacterial glycolipid mR595. The high order sites fix 1--3 micrograms glycolipid mR595/10(5) cells and those of the low order fix about 6 microgram glycolipids mR595/10(6) cells. Ca++ is required for the low order glycolipid mR595 binding to be trypsinized but not to the untrypsinized transformed rat fibroblasts. The low order binding is temperature dependent with the transition temperature lying between 25 and 37 degrees C. Exogenously added ganglioside and glycoproteins contained in the fetal calf serum do not inhibit fixation of glycolipid mR595. Only beta-lipoprotein at high concentrations is slightly inhibitory. Glycolipid mR595 fixation to transformed fibroblast does not alter their morphology and appears to slightly improve cell attachment to substratum. Glycolipid mR595 fixation results in a lengthening of the S-phase of the cell cycle and a reduction in 2-deoxyglucose uptake. Uptake of inorganic phosphate is not affected. Inhibition of phospholipid synthesis is observed in mR595 fixed fibroblasts whereas synthesis of cell surface glycoproteins and the content of cellular gangliosides is not affected.

Binding Sites↗
PubMed1979

Chloride permeability of sea urchin eggs.

We have examined the content and permeability of chloride in sea urchin eggs. After fertilization there is a large increase in the permeability to chloride. We discuss the mechanism underlying this permeability change and the generalized increase in ion permeability observed after fertilization.

Animals↗
PubMed1979

Evaluation of various methods for the detection of enteropathogenic Escherichia coli in diarrheic calves.

Evaluation of the Escherichia coli population in the small intestine of diarrheic calves was performed by estimating the number of colony-forming units and the observation of direct gram-stained smears of mucosal scrapings. Enterotoxigenicity of the isolates was determined by the infant mouse test and the ligated intestinal segment in calves. The influence of various broth culture media on the production of enterotoxin was also studied. Serologic characterization of the E coli isolates was performed. A total of 190 cases of diarrhea in bovine neonates was studied and it was found that enteropathogenic E coi was not responsible for more than 20% of the cases. A practical approach for the recognition of enteropathogenic E coli in a routine diagnostic laboratory is proposed.

Agglutination Tests↗
PubMed1978

A study of cell surface constituents restricting Salmonella minnesota R form glycopid mR595 fixation to normal rat embryo fibroblasts.

The nature of the cell surface constituent(s) containing sialic acid that block fixation of bacterial glycolipid mR595 to normal rat fibroblasts was explored. Indirect evidence suggests that a trypsin-sensitive, high molecular weight glycoprotein, present in larger amounts on the surface of normal cells (as compared with transformed rat fibroblasts), may be involved as a blocking agent.

Animals↗