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At least 523 records · Page 29Linked to original sources
PubMed1998

Leptospira genomics.

The bacterial species Leptospira interrogans (sensu stricto) has a complex genome containing two circular chromosomal replicons. Comparative analysis of the larger chromosome reveals a fluid genetic organization with many large rearrangements differentiating two closely related strains. In the present study new genes were identified by partial sequence analysis of randomly cloned fragments of L. interrogans DNA. These genes were localized in regions of the genome by nucleic acid hybridization with DNA fragments separated by pulsed-field gel electrophoresis. The resulting genetic maps provide improved resolution for each strain and provide evidence for additional chromosomal rearrangements. Insertion elements may be involved in recombination events, as several are near regions of the chromosome that have undergone rearrangement.

Chromosome Mapping↗
PubMed1976

Canine leptospirosis: an immunopathological study of interstitial nephritis due to Leptospira canicola.

In an attempt to define the pathogenetic mechanisms involved in acute interstitial nephritis due to Leptospira canicola the kidneys of 14 dogs were subjected to histological immunofluorescence and elution studies. Leptospiral antigen was found in three sites within the kidney; as discrete organisms in the proximal tubules, as granular deposits in the cytoplasm of macrophages and in large extracellular clumps in the interstitium. Deposits of IgG were also detected in the latter site and in plasma cells found in the surrounding cellular infiltrate. Anti-leptospiral antibody, mainly of the IgG class, was detected in renal eluates using both agglutination-lysis and indirect immunofluorescence. From these findings it was considered that the cellular infiltrates found in the kidneys of dogs suffering from acute leptospiral nephritis have two main functions; firstly, the local production of anti-leptospiral antibody and, secondly, phagocytosis.

Animals↗
PubMed2005

Purification and proteomic analysis of outer membrane vesicles from a clinical isolate of Leptospira interrogans serovar Copenhageni.

The severe pulmonary form of leptospirosis (SPFL) is an especially serious and rapid disease process characterized by alveolar hemorrhage and acute respiratory failure. The outer membrane of Leptospira facilitates direct interactions with the environs and likely contains important constituents involved during infection, transmission, survival, and adaptation to environmental conditions, including putative vaccinogen and diagnostic candidates. Outer membrane vesicles (OMVs) were purified by incubation in low-pH citrate buffer, treatment in a French press, and centrifugation over a continuous sucrose gradient. OMVs characterized by two-dimensional gel electrophoresis (2-DE) contained the previously described outer membrane proteins OmpL1, Qlp42, LipL32, LipL41, LipL36 and Loa22. In addition, unknown, hypothetical and putative outer membrane proteins were identified. High-performance liquid chromatography (HPLC) coupled with mass spectrometry and fraction collection (LC-MS+) measured the intact mass profile of the major outer membrane protein, LipL32, and the putative lipoprotein Qlp42. In contrast to a predicted molecularmass of 27,653.5 Da for LipL32 after cleavage of its signal peptide, intact mass proteomics measured the mass as ranging from 28,468 to 28,583 Da, consistent with lipidation of LipL32. In contrast to a predicted molecular mass of 39.8 kDa for Qlp42, the actual mass was measured as 24,811 and 26,461 Da consistent with a 30 kDa doublet observed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels and processing of the N-terminus of the mature protein. These studies indicate that purified OMVs are highly compatible with proteomics technologies including 2-DE and intact mass proteomics using LC-MS+ that facilitates definition of actual molecular masses of intact outer membrane proteins, and heterogeneity associated with them.

Amino Acid Sequence↗
PubMed1999

Genetic organization of the lipopolysaccharide O-antigen biosynthetic locus of Leptospira borgpetersenii serovar Hardjobovis.

Leptospiral LPS plays a critical role in immunity to leptospirosis and forms the basis for serological classification of Leptospira. However, neither the structure of leptospiral LPS nor the genetics of its biosynthesis have been elucidated. A probe derived from the rhamnose biosynthetic genes of L. interrogans serovar Copenhageni was used to identify the rfb locus of L. borgpetersenii serovar Hardjobovis. Chromosome walking and sequence analysis revealed an rfb locus spanning 36.7 kb, which consists of 31 ORFs transcribed in the same direction. Clusters of genes were identified which encode proteins related to enzymes involved in the biosynthesis of activated sugars including rhamnose. Additional ORFs in the locus encode glycosyltransferases for the assembly of the O-antigen subunit and integral membrane proteins for the transport of O-antigen subunits through the membrane and assembly into LPS.

Amino Acid Sequence↗
PubMed2002

Leptospira interrogans binds to the CR3 receptor on mammalian cells.

Pathogenic leptospires adhere to phagocytes even in the absence of specific antibodies; we demonstrate that the CR3 integrin (known as Mac-1 or CD11b/CD18 receptor), expressed on neutrophils and CHO Mac-1 transfected cells, recognizes and binds leptospires. The I-domain of the molecule seems to be involved in the recognition and data suggest that this occurs via fibronectin absorbed at the Leptospira surface. On the other hand, since N-acetyl-D-glucosamine does not behave as antagonist of the binding, the lectin-like domain of the receptor is not involved in the recognition.

Animals↗
PubMed1994

Nucleotide sequence analysis of IS1533 from Leptospira borgpetersenii: identification and expression of two IS-encoded proteins.

The nucleotide sequence of IS1533, an insertion sequence-like element cloned from the spirochete Leptospira borgpetersenii, was determined. IS1533 contains imperfect terminal inverted repeats (IVR) of 31 bp flanking a 1402-bp internal sequence. A putative target sequence was identified, and insertion may result in duplication of 2 bp. The internal sequence has a single open reading frame (ORF). IS1533 encodes two proteins (43.5 and 41 kDa) initiating alternatively at either the first or the second AUG codons of the ORF. These proteins are related to a recently recognized family of IS-encoded transposases and bacterial recombinases, all which share a region of homology with the active site of the HIV reverse transcriptase. The IS1533-encoded proteins were expressed in Escherichia coli. Both the 43.5- and 41-kDa proteins bound IS1533 DNA probes in a Southwestern blot assay. These data suggest that one or both proteins function during transposition of IS1533.

Amino Acid Sequence↗
PubMed1984

Adhesion of Leptospira at a solid-liquid interface: a model.

Two strains of the saprophytic Leptospira biflexa serovar patoc display reversible and irreversible adhesion at a solid-liquid interface. Both forms of adhesion are enhanced in the presence of 20 microM carbonyl cyanide meta-chlorophenyl hydrazone (CCCP), an uncoupler which inhibits motility of the bacteria. Microscopic observations also indicated that motility may have a role in adhesion as only actively motile organisms were seen to detach from the substratum. A dynamic model is proposed for adhesion of these organisms at a solid-liquid interface. It is suggested that the level of reversible adhesion is determined by the comparative rates of attachment (ON phase) and detachment (OFF phase). As reversible adhesion is mediated by weak forces of attraction, bacterial motility or gentle washing could promote the OFF phase. When motility is inhibited, the OFF phase is reduced and the ON phase continues (as motility is not required for the ON phase) causing the level of reversible adhesion to increase. Since reversible adhesion is a prerequisite for irreversible adhesion, then increased reversible adhesion leads directly to increased irreversible adhesion. Reversible adhesion appears to be mediated by the weak attractive forces of the "secondary minimum" whereas the mechanism facilitating irreversible adhesion of leptospires is not known.

Leptospira↗
PubMed1978

Leptospirosis in Colombia: isolation of Leptospira spp. from the kidneys of brown rats (Rattus norvegicus) trapped on infected piggeries.

Leptospira interrogans serotypes pomona and icterohaemorrhagiae were isolated from the kidneys of Rattus norvegicus trapped on pomona infected piggeries. The isolation of pomona from one of 111 cultured kidneys, although of interest, strongly suggests that this rat does not play an important part in the epidemiology of infection by this serotype. Kidney tubular degeneration, focal mononuclear infiltrations and fibroplasia are morphological traces which remain after an attack of leptospirosis. The high percentage (48.6) of these lesions found in the rat kidneys examined does not seem to be related to serotype pomona but to icterohaemorrhagiae. The importance of this last serotype in swine in the Cauca Valley has yet to be assessed.

Animals↗
PubMed1991

Leptospira interrogans serovar canicola: a causal agent of sow abortions in Arequipa, Peru.

An outbreak of abortions, stillbirths, mummified piglets and neonatal deaths in a pig herd in Arequipa, Peru is described. A total of 31 of 240 sows aborted between May and September 1988. When sera were examined 12 of 14 had very high titres of antibody to canicola PC125 and canicola Hond Utrecht, but there were also high titres of antibody to other leptospiral serovars. A detailed investigation was made and serovar canicola PC125 was isolated from the urine of four sows which had aborted and the kidney of one slaughter pig. Antibodies to various serovars of Leptospira were demonstrated in 11 of 17 sows which had aborted, two of six sows which had normal litters, nine of 18 boars, four of 39 slaughter pigs and four of 14 workers on the farm. The outbreak was brought under control by treatment and vaccination coupled with a thorough cleaning of the farm and control of the wild animal population. It is suggested that the infection was brought onto the farm by wild animals and that the disease is more common in Arequipa than was previously supposed.

Abortion, Veterinary↗
PubMed2005

Annual variations in Leptospira seroprevalence among sows in southern Vietnam.

A serological survey was conducted among sows in the Mekong delta in southern Vietnam in 1999 to investigate variations in leptospiral seroprevalence over a one-year period. In this region, leptospirosis is endemic and a high leptospiral seroprevalence has been shown in the pig population. In this study, the serology of six Leptospira serovars was analysed by the microscopic agglutination test for 429 sows at five large-scale state farms sampled during the dry period, the rainy period and the early dry period. The serovars included were L. interrogans serovar (sv) autumnalis strain Akiyama A, L. interrogans sv bratislava strain Jez, L. interrogans sv icterohaemorrhagiae strain Kantorowicz, L. interrogans sv pomona strain Pomona, L. borgpetersenii sv tarassovi strain Perepelitsin, and L. kirschneri sv grippotyphosa strain Duyster. Variations in seroprevalence over the year were found for sv bratislava and sv icterohaemorrhagiae: the seroprevalence was higher during the dry period compared with the rainy period (p = 0.07 and p = 0.005, respectively) and the early dry period (p = 0.00006 and p = 0.0006, respectively). It is concluded that in regions where water is constantly abundant and where animals are exposed to the outdoor environment all year round there are highly significant variations in leptospiral seroprevalence over the year.

Agglutination Tests↗
PubMed1986

Morphological changes in red blood cells of calves caused by Leptospira interrogans serovar pomona.

Haemoglobinaemia is seen in certain hosts infected by certain serovars of Leptospira interrogans, but is absent from other serovar-host associations. Comparisons were made between calves infected with serovar pomona and those receiving a crude "toxin" prepared from the same organism. Red blood cells from "toxin"-injected calves showed discocyte-echinocyte transformation and contained portions of cytoplasm segregated within vacuoles. These animals showed increased sequestration of RBCs within the spleen but no overt haemoglobinaemia. Red blood cells from infected and haemoglobinaemic animals were spherical and pitted. They also showed vacuoles and tracts under the cell membrane in fully haemoglobinized RBCs and dark granular inclusions within the cytoplasm of those which were only partially haemoglobinized. Intracellular leptospires were not seen within the RBCs. Red blood cell sequestration and erythrophagocytosis were very pronounced within the spleen, liver and bone marrow. The changes in the RBCs are not easily explained by the previously proposed theory that RBC destruction is due to a phospholipase-like toxin acting directly upon the RBC membrane. A more appropriate hypothesis is that the RBC lesions are due to the adverse effects of leptospiral "toxin(s)" on the metabolism of the RBC causing the formation of defective portions of cytoplasm. These are then either degraded and expelled, leaving empty vacuoles, or are degraded and left within the cytoplasm as dark granular inclusions.

Animals↗
PubMed1984

Isolation of Leptospira from wild forest animals in Amazonian Brazil.

The role of wild, forest animals as reservoirs of Leptospira was investigated in Pará State, north Brazil. 696 animals were examined by culture of kidney tissue; isolates of serovar ballum were made from the rodent Proechimys sp. and the opossum Didelphis marsupialis; leptospires of the serogroups hebdomadis, grippotyphosa and cynopteri were isolated from the armadillo Dasypus novemcinctus, and as yet untyped leptospires were isolated from Proechimys and the procyonid carnivore Nasua nasua. Antibodies to serovars bataviae, butembo, canicola, castellonis, celledoni, grippotyphosa, panama, icterohaemorrhagiae and wolffi were demonstrated among 222 other animals examined by serological methods.

Animal Population Groups↗
PubMed1986

The development of a potency test for Leptospira hardjo vaccines: a comparison of protection in calves and serology in guinea-pigs.

The protective properties of two commercial Leptospira hardjo vaccines in calves were compared with the serological responses induced in guinea-pigs with a view to establishing a potency test based on serology. Groups of calves were given graded doses of the two vaccines and after eight weeks were challenged with virulent L. hardjo. Infection was monitored by microscopy and culture of urine and, eight weeks after challenge, by culture of the kidneys post mortem. Groups of guinea-pigs also were tested by the microscopic agglutination test (MAT). A clear dose response was observed and the response was related to the degree of protection achieved in the calves. The MAT titre in guinea-pigs indicative of an effective vaccine was calculated for the minimum dose of each vaccine that gave full protection in calves. A close correlation was observed. Two further batches of each vaccine were tested in guinea-pigs on two occasions with reproducible results. A potency test based on the MAT response of guinea-pigs is proposed.

Agglutination Tests↗
PubMed1990

The detection of genetic variation in Leptospira interrogans serogroup ICTEROHAEMORRHAGIAE by ribosomal RNA gene restriction fragment patterns.

Deoxyribonucleic acid from Leptospira interrogans serogroup ICTEROHAEMORRHAGIAE reference strains together with clinical and animal isolates were cleaved with EcoRI, electrophoresed and transferred to nylon membranes. An Escherichia coli MRE 600, 16S + 23S ribosomal RNA template was used in the synthesis of a single strand biotin-labelled cDNA probe using a reverse transcriptase. Ribosomal RNA cistrons present in the DNA fragments of strains were located using the cDNA probe. Between 4 and 7 well defined ribosomal RNA restriction bands were detected for the leptospires studied that varied in size from 12.1 to 0.57 kb. The hybridisation patterns were distinctive and unique for the reference strains that allowed for their characterisation. Similar patterns were observed for I. budapest M 20, I. "icterohaemorrhagiae" Ictero I and the type strain, I. icterohaemorrhagiae RGA. Clinical isolates and a isolate from a rat were compared with reference strain DNA patterns and identified as being similar to I. copenhageni M 20, I. "icterohaemorrhagiae" Ictero I and I. icterohaemorrhagiae RGA. These results indicate that ribosomal DNA fingerprinting may be useful in the classification and molecular epidemiology of pathogenic leptospires.

DNA Probes↗
PubMed1984

Cloning of a gene required for tryptophan biosynthesis from Leptospira biflexa serovar patoc into Escherichia coli.

A clone bank, consisting of approx. 8100 colonies, has been created for the spirochete Leptospira biflexa serovar patoc in Escherichia coli using pBR322 as the vector. One of these clones contains the genetic information needed to complement a defect in the trpE gene of E. coli. The information resides on a 20.5-kb plasmid designated pYC1, which carries a 16-kb insert consisting of three HindIII fragments. It does not complement defects in other genes needed for the biosynthesis of tryptophan in E. coli.

Chromosome Mapping↗
PubMed1995

Cloning of the pfaP gene of Leptospira borgpetersenii.

A lambda gt11 library constructed with Leptospira borgpetersenii DNA was screened with monoclonal antibodies (mAb) recognizing a periplasmic flagella-associated protein. A plaque expressing a fusion protein (lambda F15) which reacted with the mAb was isolated and the nucleotide sequence analyzed. The deduced amino-acid (aa) sequence indicates that the pfaP gene belongs to a group of bacterial genes whose products share aa sequence and possibly functional homologies with sppA, an Escherichia coli signal peptidase-encoding gene.

Amino Acid Sequence↗
PubMed1995

Sequence of the Leptospira biflexa serovar patoc recA gene.

The nucleotide (nt) sequence of the recA gene of Leptospira biflexa serovar patoc strain Patoc I has been determined. The deduced amino acid (aa) sequence of the RecA protein is 387 aa long with a predicted molecular mass of 42,355 Da. The aa sequence has a high degree of identity to the aa sequences of many bacterial RecA, including Pseudomonas fluorescens, Escherichia coli and Bacillus subtilis. This is the first recA sequence reported for a bacterium in the order Spirochaetales.

Amino Acid Sequence↗