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PubMed1978

Distribution of the genus Leptospira in soil and water.

The distribution of the aerobic spirochetes Leptospira in surface waters, soil, and aquatic animals was investigated. Isolates from water and soil exhibited physiological characteristics common to members of the "biflexa complex," none were capable of infecting experimental animals, and leptospires could not be isolated from the eight genera of aquatic animals examined. The isolation frequencies from surface waters were: stream, 100%; lake, 65%; spring, 28%; bog lake, 5%; and marsh, 0%. With the exception of the stream, more isolations were obtained from the soil adjacent to the water than from the water. Leptospires were most frequently associated with soils of high moisture and organic matter content.

Amphibians↗
PubMed1970

Naphthylamidase activity of Leptospira.

Extracts of 18 serotypes of the genus Leptospira were found to possess naphthylamidase activity, and differences in the pathogenic and saprophytic strains were noted. The former exhibited a preference for the leucyl naphthylamide substrate, whereas the latter demonstrated greater hydrolysis of alanyl naphthylamide. With the leucyl naphthylamide as substrate, pathogenic strains showed 10 to 20 times higher naphthylamidase activity than saprophytic strains. Optimal temperature and pH for enzymatic hydrolysis also differed between pathogenic and saprophytic strains. Maximal enzymatic activities for pathogenic and saprophytic naphthylamidases were 41 and 37 C, respectively, at pH 8.0 to 8.5. The pH and temperature optima suggested that the leptospiral enzyme activity was not leucine aminopeptidase.

Alanine↗
PubMed1973

Survivor curves for Leptospira autumnalis Akiyami A based on most-probable-number values.

The validity of survivor curves for Leptospira autumnalis Akiyami A based on most-probable-number values is supported by the following observations: (i) linear regression lines fell within most of the 95% confidence intervals; (ii) linear correlation coefficients (r) were consistently high (i.e., near -1); and (iii) statistical tests for goodness of fit usually accepted the linear model. These tests are consistent with an exponential death rate for the test organism in defined solutions. The influence of temperature and pH on survival was demonstrated by showing a statistically significant difference in survivor curve slopes.

Bacteriological Techniques↗
PubMed1975

Pathogenic leptospiras isolated from Malaysian surface waters.

Pathogenic leptospiras (1,424) isolated from natural waters and wet soils in Malaysia comprised 29 different serovars (synonym serotypes). All except two of the serovars had been found previously in Malaysia. The exceptional serovars were werrasingha, an Autumnalis serogroup member originally isolated in Ceylon, and a new serovar designated evansi. Serovar evansi had serological affinities with serovar ranarum which was isolated from the kidney of a frog in Iowa. The large variety of serovars found in jungle areas was consistent with similar previous findings of diverse serovar infections in troops who had operated in Malaysian jungles.

Agglutination Tests↗
PubMed2003

Interleukin 12 in part regulates gamma interferon release in human whole blood stimulated with Leptospira interrogans.

Heat-killed pathogenic Leptospira interrogans serovar rachmati induced the production of gamma interferon (IFN-gamma) and the IFN-gamma-inducing cytokines interleukin-12p40 (IL-12p40) and tumor necrosis factor alpha in human whole blood in vitro. The production of IFN-gamma was largely dependent on IL-12. These data establish that pathogenic leptospires can stimulate the production of type I cytokines involved in cellular immunity.

Humans↗
PubMed2001

Competitive enzyme-linked immunosorbent assay for detection of Leptospira interrogans serovar pomona antibodies in bovine sera.

A competitive enzyme-linked immunosorbent assay (ELISA) using a specific monoclonal antibody (M898) was developed for detection of bovine antibodies to Leptospira interrogans serovar pomona. This assay was evaluated using field sera (n = 190) with serovar pomona microscopic agglutination test (MAT) titers of > or =100 as the positive population (group A); field sera (n = 1,445) which were negative in the MAT (1:100 dilution) for serovar pomona (group B); and sera (from a specific-pathogen-free cattle herd [n = 210]) which were negative in the MAT (1:100 dilution) for serovars canicola, copenhageni, grippotyphosa, hardjo, pomona, and sejroe (group C). At the cutoff point recommended by receiver operating characteristic (ROC) curve analysis of the combined ELISA results of serum groups A, B, and C, the sensitivity and specificity values were 93.7 and 96.3%, respectively. The value for the area under this ROC curve was 0.977, indicating a high level of accuracy for the ELISA. Similar results were obtained from the analysis of the combined results of serum groups A and B and from the analysis of the combined results of serum groups A and C.

Animals↗
PubMed1974

Urea utilization by Leptospira.

One representative of each of five different pathogenic serotypes of Leptospira as well as one saprophytic strain were capable of growing on medium containing urea in place of an ammonium salt as a nitrogen source. Growth of all of the organisms tested on 1% urea was substantial, but only those that exhibited strong urease activity could grow to any appreciable extent on urea at a concentration as high as 2%. Intact urea-grown cells of the pathogenic serotypes tested (grippotyphosa and icterohaemorrhagiae) exhibited urease activity, with the level of activity of the former being considerably greater. No urease could be detected in cells of the saprophytic strain. When the pathogenic leptospires were sonicated or treated with toluene, the urease activity was greatly enhanced. When cultivated on NH(4)Cl, neither intact nor disrupted cells of any of the strains tested exhibited any urease activity. Cells of the grippotyphosa and icterohaemorrhagiae strains exhibited diauxic growth when cultivated in the presence of both NH(4)Cl and urea, whereas only monophasic growth could be detected for the saprophytic test strain. The experimental data on urea utilization and urease activity, when considered in the light of previously reported findings on leptospiral pathology, renal physiology, and the role of urease in other bacterial infections, suggests a significant role for leptospiral urease (in addition to other factors) in determining localization of the organism in the kidney and contributing to the resultant kidney pathology.

Ammonium Chloride↗
PubMed1975

Possible role of protein(s) as antigenic determinant of the type-specific main antigen of Leptospira kremastos strain Kyoto.

Acid hydrolysates of the type-specific main (TM) antigen isolated from Leptospira kremastos strain Kyoto showed a considerable inhibition of complement fixation reaction between TM antigen and anti-strain Kyoto serum. A fraction of 2 N HCl hydrolysate containing exclusively a large amount of neutral sugars showed no inhibition, whereas another fraction containing only a small amount of protein(s) showed a slight inhibition. The remaining fractions containing amino sugars, protein(s), and neutral sugars showed a slight inhibition, but the inhibition did not correlate with the amount of amino sugars. TM antigen, delipidized by hydrolysis with 1 N HCl for 4 min and then dialysis, showed a strong inhibition. The lipid fraction did not show any inhibition. The inhibitory effect of nondialyzable delipidized TM antigen was completely lost by treating the antigen with proteolytic enzymes, indicating that the antigenic determinant of L. kremastos strain Kyoto is intimately related with protein(s).

Antigens, Bacterial↗
PubMed1976

Susceptibility of mice treated with cyclophosphamide to lethal infection with Leptospira interrogans Serovar pomona.

Mice not normally susceptible to infection with Leptospira interrogans serovar pomona were rendered susceptible to lethal infections by treatment with a single dose of 300 mg of cyclophosphamide (Cy) per kg administered optimally from 4 days before to 1 day after infection. Cy-treated mice with either passively or actively acquired antibody were protected from death. Blood levels of leptospires in infected untreated and in Cy-treated mice remained similar until 2 days after infection, when untreated mice cleared the leptospires. Soon afterwards, opsonizing and agglutinating antibody appeared. Cy-treated mice given spleen cells from other normal or specifically immune mice were protected from infection. An important factor in the natural resistance of mice to leptospiral infection appears to be their capacity to produce circulating antibody within 48 to 72 h. Applications are suggested for this animal model in vaccination and protection studies.

Animals↗
PubMed1979

Suppression of antibody response to Leptospira biflexa and Brucella abortus and recovery from immunosuppression after Berenil treatment.

Zebu cattle infected with either Trypanosoma congolense EATRO 1800 or Trypanosoma vivax EATRO 1721 had suppressed humoral immune responses to Leptospira biflexa injected intravenously and to attenuated Brucella abortus injected subcutaneously. T. congolense infections were more suppressive than T. vivax infections. In cattle infected with T. vivax, the suppression of immune responses to both bacterial immunogens was abrogated when the animals were treated with Berenil at the time of antigen administration. In cattle infected with T. congolense, simultaneous Berenil treatment at the time of vaccination abolished the suppression of immune response to L. biflexa, and lessened but did not abrogate the suppression of immune response to B. abortus.

Amidines↗
PubMed1972

Isolation of the outer sheath of Leptospira and its immunogenic properties in hamsters.

Spherical forms of Leptospira interrogans serotype canicola Hond Utrecht IV were induced with 1 m NaCl. Electron micrographs of these salt-altered cells (SAC) revealed that the outer envelope or sheath had pulled away from the protoplasmic cylinder. Treatment of SAC with 0.02% sodium lauryl sulfate solubilized the sheath and released the protoplasmic cylinder. Further processing of the solubilized sheath yielded a pellet which displayed a membrane structure in electron micrographs. The released protoplasmic cylinder showed loss of intracellular organization and the outer envelope present in normal cells. Immunization of hamsters with whole formalized cells, SAC, or sheath in doses as low as 10 mug/animal protected them from death upon challenge with virulent canicola 27.

Animals↗
PubMed1986

Copurification of Leptospira interrogans serovar pomona hemolysin and sphingomyelinase C.

The hemolytic and sphingomyelinase C activities of supernatants of cultures of Leptospira interrogans serovar pomona tended to copurify when isoelectric fractionation was carried out. Both activities focused primarily at pH 8.1. Considered in conjunction with other circumstantial evidence, the results led to the conclusion that sphingomyelinase C is responsible for hemolysis.

Hemolysin Proteins↗
PubMed1989

Immunological characteristics of the glycolipid antigen of Leptospira interrogans serovar lai.

The protective antigen (PAg), a glycolipid substance, was extracted from Leptospira interrogans serovar lai strain 017 with a chloroform-methanol-water (1:2:0.8 [vol/vol/vol]) solution and partially purified by silica gel column chromatography. The PAg was not detected by Coomassie brilliant blue staining in sodium dodecyl sulfate-polyacrylamide gel electrophoresis but was observed as a smearlike band, which corresponded to a 24- to 30-kilodalton standard protein, by silver staining. The outer envelope (OE) fraction showed the same band, suggesting that the PAg was one of the chemical components of the OE. The immunogenicity and protective activity of the PAg were compared with those of the OE. The PAg as well as the OE and whole cells was able to induce agglutinating antibody against L. interrogans. Furthermore, the immune sera exhibited opsonic activity against L. interrogans, as observed by measurement of chemical luminescence derived from reactive oxygen. The PAg exhibited protective activity in hamsters challenged with lethal doses of L. interrogans. Therefore, the antigen may be useful as a component vaccine against leptospiral infection.

Agglutination Tests↗
PubMed1989

Cloning of a hemolysin gene from Leptospira interrogans serovar hardjo.

A DNA fragment encoding both hemolysin and sphingomyelinase C activity was cloned from the pathogenic bacterium Leptospira interrogans serovar hardjo. Initial clones were obtained by screening a genomic library in EMBL3 for hemolytic activity. Both hemolytic and sphingomyelinase C activities were coded for by a 3.9-kilobase BamHI fragment. The hemolysin was expressed from its own promoter in Escherichia coli K-12. Similar DNA sequences were also present in the serovars tarassovi and ballum.

Cloning, Molecular↗