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PubMed2004

Cell aggregation: a mechanism of pathogenic Leptospira to survive in fresh water.

Transmission of leptospirosis is facilitated by the survival of pathogenic leptospires in moist environments outside their mammalian host. In the present study, the survival mechanisms of Leptospira interrogans serovar Canicola in aqueous conditions and lack of nutrients were investigated. In distilled water, leptospires were able to remain motile for 110 days (pH 7.2). However, when incubated in a semi-solid medium composed of distilled water and 0.5% purified agarose (pH 7.2), they survived 347 days. In this viscous environment, aggregates of live spirochetes were observed. Neither antibiotics (e.g. tetracycline and ampicillin) nor nutrients inhibited leptospiral aggregation. Immunoblot analysis suggested that cells incubated in water down-regulate the expression of LipL31, an inner-membrane protein, but retain expression of other membrane proteins. These studies provide insights into the mechanisms by which pathogenic Leptospira survives for prolonged periods of time in natural aqueous environments, a key stage in the leptospiral lifecycle.

Animals↗

PubMed2004

[Exposure to Leptospira in stray dogs in the city of Cali].

In Colombia, little information is available concerning the epidemiology of leptospirosis in urban environments. Furthermore, the role of dogs in the transmission cycle of leptospirosis in the urban setting is unclear. To explore the potential role of canines in the transmission of leptospirosis in Cali, a serological study was conducted with 197 serum samples collected from stray dogs during 2001 and 2003. Serum specimens were screened with the Microscopic Agglutination Test (MAT) and 7 serovars--Icterohaemorrhagiae, Canicola, Gryppotyphosa, Hardjo strain Hardjobovis, Pomona, Hardjo strain Hardjoprajitno and Bratislava. All serovars were provided by the Instituto Colombiano Agropecuario (ICA), Tuluá, Colombia. The MAT was considered positive when 50% or more leptospiras were agglutinated with one or more serovars in a serum dilution of 1:100. At least one serovar showed evidence of infection in 41.1% of the dogs. The most prevalent serovar was Icterohaemorrhagiae, found in 55.6% of the seropositive dogs. 48.1% were co-agglutinations. No reactions against the serovars Pomona, Hardjo strain Hardjoprajitno and Bratislava were observed. These findings suggested that stray dogs are potential reservoirs of Leptospira in Cali and underscored the need to study the epidemiology of this disease in Colombia.

Agglutination Tests↗

PubMed2005

Diversity of bat-associated Leptospira in the Peruvian Amazon inferred by bayesian phylogenetic analysis of 16S ribosomal DNA sequences.

The role of bats as potential sources of transmission to humans or as maintenance hosts of leptospires is poorly understood. We quantified the prevalence of leptospiral colonization in bats in the Peruvian Amazon in the vicinity of Iquitos, an area of high biologic diversity. Of 589 analyzed bats, culture (3 of 589) and molecular evidence (20 of 589) of leptospiral colonization was found in the kidneys, yielding an overall colonization rate of 3.4%. Infection rates differed with habitat and location, and among different bat species. Bayesian analysis was used to infer phylogenic relationships of leptospiral 16S ribosomal DNA sequences. Tree topologies were consistent with groupings based on DNA-DNA hybridization studies. A diverse group of leptospires was found in peri-Iquitos bat populations including Leptospira interrogans (5 clones), L. kirschneri (1), L. borgpetersenii (4), L. fainei (1), and two previously undescribed leptospiral species (8). Although L. kirschenri and L. interrogans have been previously isolated from bats, this report is the first to describe L. borgpetersenii and L. fainei infection of bats. A wild animal reservoir of L. fainei has not been previously described. The detection in bats of the L. interrogans serovar Icterohemorrhagiae, a leptospire typically maintained by peridomestic rats, suggests a rodent-bat infection cycle. Bats in Iquitos maintain a genetically diverse group of leptospires. These results provide a solid basis for pursuing molecular epidemiologic studies of bat-associated Leptospira, a potentially new epidemiologic reservoir of transmission of leptospirosis to humans.

Animals↗

PubMed2006

A histopathological study of hearts and spleens of hamsters (Mesocricetus auratus) infected with Leptospira interrogans, serovar pyrogenes.

The effects of Leptospira interrogans on the heart and spleen of hamsters were studied histopathologically. Infected hamsters were sacrificed at 1 hour, 6 hours and on days 1, 2, 3, 4, 5 and 6 after inoculation with Leptospira interrogans serovar pyrogenes. The heart and spleen of each of the sacrificed animals were removed and processed for routine conventional light microscopy. Infected hearts showed degenerative change of the cardiac muscle cells composed of cellular swelling, condensation of chromatin granules, pyknotic nuclei and acidophilic cytoplasm. Congestion of the cardiac blood vessels and hemorrhagic areas were found. Necrosis of the cardiac muscle cells was surrounded by numerous inflammatory cells. In the spleen, cellular necrosis was found scattered throughout the splenic cord. The splenic sinusoids were dilated and congested with many hemorrhagic areas. Inflammatory cell infiltration was also noted in the splenic parenchyma and the splenic sinusoids.

Animals↗

PubMed1990

Species differentiation of Leptospira interrogans serovar hardjo strain Hardjobovis from strain Hardjoprajitno by DNA slot blot hybridisation.

Slot blot hybridisation studies with total genomic DNA probes were used to compare Leptospira interrogans serovar hardjo strain Hardjoprajitno, strain Hardjobovis and a number of other Leptospira interrogans serovars. Strains Hardjoprajitno and Hardjobovis were found to have little genetic relationship with each other when compared to some of the other serovars tested. Hardjoprajitno is closely related to serovar icterohaemorrhagiae and not to Hardjobovis whereas Hardjobovis is closely related to serovars vietnam, balcanica and javanica but not to serovar icterohaemorrhagiae; this places strain Hardjoprajitno in the species L interrogans and strain Hardjobovis in the species L borgpetersoni. Because of this lack of genetic relatedness between strains Hardjoprajitno and Hardjobovis, it is proposed to remove the prefix Hardjo from the strain name Hardjobovis and call it L borgpetersoni serovar hardjo strain Bovis.

Animals↗

PubMedDate not supplied

[The development of a complex Leptospira antigenic erythrocyte diagnostic agent].

Blood-sensitive activity of antigenic extracts obtained from leptospiras using the supersound and sodium dodecyl sulphate has been studied. Erythrocytic diagnostica, obtained on the basis of the mentioned sensitines, possess the genus and serogroup specificity, which expands their diagnostic spectrum. New diagnostica are shown to possess higher sensitivity as compared with the previously developed leptospirosis genus-specific erythrocytic diagnostica. The data are presented confirming the prospects of development of erythrocytic diagnostica based on antigens of leptospiras obtained by means of a supersound and sodium dodecyl sulphate. These preparations may be used in the diagnosis of human and animal leptospirosis.

Animals↗

PubMed1989

[Electrophoretic study of the outer membrane proteins of leptospirae].

The outer membranes of pathogenic and saprophytic leptospires have been isolated. The spectrum of outer membrane proteins in three saprophytic and one pathogenic Leptospira strains has been studied by means of electrophoresis in polyacrylamide gel. In Leptospira strains VGNKI-6 (pathogenic) and G-80 (saprophytic) identical proteins, as well as proteins similar in their Rf value, have been detected. The possibility of using strain G-80 for the development of leptospiral vaccine against serovars having common surface antigens with this strain has been suggested.

Bacterial Outer Membrane Proteins↗

PubMed1988

[Populations of pathogenic Leptospira of varying virulence in nature].

The study of geographically remote populations of Norway rats (Rattus norvegicus) revealed that in one of these populations a highly virulent population of Leptospira copenhageni, serogroup icterohaemorrhagiae, and in another population of rats a faintly virulent population of these microorganisms circulated simultaneously. At the same time in vitro experiments with Leptospira cultures showed the absence of the constant probability of sharp changes in the level of their virulence in time.

Animals↗

PubMed1985

[Anti-leptospira and anti-brucella agglutinins in hares (Lepus europaeus) from Rio Cuarto Department, Province of Cordoba].

Seventy-seven anti-brucella and 42 anti-leptospira agglutinin serum levels of hares in Rio Cuarto district of Córdoba Province were studied. For brucella, only one sample showed incomplete reaction at a 1:25 dilution. The isolation of brucella from liver, spleen and gastro-hepatic lymph node in this animal was negative. In the 42 serum samples examined for L. pomona, L. wolffi, L. ballum, L. hardjo, L. pyrogenes and L. grippotiphosa, 6 reacted at a dilution of 1:100 with L. ballum serovar and 1 reacted up to 1:200 dilution with L. wolffi serovar. These results indicate that the hare does not play any important role as reservoir of pathogenic brucella in this area. Meanwhile, it could act as potential reservoir for pathogenic leptospira.

Agglutinins↗

PubMed1985

Comparative study of four saprophytic leptospira strains as screening antigens in the serodiagnosis of leptospirosis in water buffaloes (Bubalus bubalis).

The profitability of four saprophytic leptospira strains (Buenos Aires, Patoc 1, Rufino and São Paulo) as polyvalent antigen in the serodiagnosis of leptospirosis in water buffaloes was studied by the microscopic agglutination test. From 104 examined sera tested against 16 pathogenic leptospira serotypes, 52 were positives and 52 were negatives. The results led to the conclusion that from four studied strains, Buenos Aires strain showed the best results when utilized in screening tests for the serodiagnosis of leptospirosis in water buffaloes. The other three strains showed a good specificity but their sensibilities were poor and therefore should not be recommended for diagnosing water buffalo leptospirosis.

Animals↗

PubMed1979

[Classification of Leptospira isolated in Peru].

Antigenic properties of 23 leptospira cultures isolated in Peru were studied by immunological absorption. Two new individual leptospira serovars were classified as huanuco with a reference strain M-4, representing a new Huanuco serological group, and san-martini with a reference strain CT-63 belonging to the Hebdomadis serological group. Besides for the first time in the American part of the world serovar budapest belonging to Icterohaemorrhagiae serological group was recorded; also the first finding of serovar pyrogenes of the pyrogenes serological group was certified.

Animals↗

PubMed1979

[Dynamics of Leptospira colony formation on solid nutrient media].

The formation of Leptospira colonies on solid culture media varying in composition were studied. In all species of Leptospira 3 main periods of colony development were revealed, each of them having its characteristic morphological changes connected with the growth of the colony deeply into agar.

Culture Media↗

PubMed1975

Isolation and identification of leptospira hardjo from cattle in Argentina.

A serological evaluation was done on the prevalence of bovine leptospirosis in Argentina. In 1,857 serum samples obtained from the major cattle raising areas of the country, 59.1 percent showed leptospiral agglutinins in the microscopic-agglutination test. The most frequent leptospiral antigens showing antibody reactions were the hebdomadis group serotypes, of which 45.8 per cent of the sera reacted to Leptospira hardjo with titres ranging from 1:100 to 1:25,600. Six Leptospira isolations were made from 161 bovine kidneys collected at local abattoirs. Their isolation and subsequent identification as serotype L. hardjo is described. This study reports on L. hardjo in cattle of Argentina for the first time and confirms the need for improved cultural methodology for its isolation.

Agglutination Tests↗

PubMed1979

Antibodies against Leptospira biflexa serotypes patoc and são paulo in pigs: possible occurrence and importance for the intracutaneous test for leptospirosis.

Leptospirin for the diagnosis of leptospirosis by an intracutaneous test contains antigenic material from 5 pathogenic Leptospira serotypes (10). During experiments with rabbits and pigs, leptospirin was injected into 6 pigs which had been infected artificially with apathogenic Leptospira biflexa serotypes patoc and são paulo. Three out of the 6 pigs showed a positive leptospirin reaction (11). This interfering reaction in animals having been infected with apathogenic L. biflexa was the reason to investigate the occurrence of biflexa antibodies in pigs from different areas in Germany by the microscopic agglutination. None of the 854 pigs showed biflexa antibodies producing a 50% agglutination at a serum dilution of 1:100. If at all, pigs may become infected naturally by L. biflexa; this apparently seems to be a rare incident. An impairment of the diagnostic value of leptospirin by L. biflexa antibodies can be excluded.

Animals↗

PubMed1981

Unstable antigenic variation of leptospiras.

The antigenic variants which were found in leptospiras, Leptospira interrogans serovar copenhageni Shibaura grown in a liquid medium containing a homologous antiserum were found to be unstable. The unstable variants showed decreased agglutinability against the homologous antiserum. The decreased agglutinability of the unstable variants reverted to the parent's level of agglutinability after 1 or 2 passages through the normal serum medium. The unstable variants differed antigenically from the parent in the agglutinin-absorption test; however, the agglutinin-absorption test was found to be inadequate for showing the antigenic difference between the parent and the unstable variants because their difference was diminished when the agglutinin-absorbed antigen was increased. The application of Laurell rocket immunoelectrophoresis (LRI) to the SDS-extracted antigens revealed the distinct difference between the parent and the unstable variants. Other findings presented herein indicated the difference between the antigens of the parent and the unstable variants to be one of quantity. The magnitude of the quantitative difference between the antigens could be modified by the medium containing various concentrations of the homologous antiserum. The clones of the unstable variant showed antigenic characteristics which were similar to the original unstable variant.

Agglutination Tests↗

PubMed1982

Antigenic variants of leptospiras detected in peritoneal cavity in early stage of infection in immunized guinea pigs.

Antigenic variants were detected firstly 7 h following intraperitoneal challenge with Leptospira interrogans serovar copenhageni Shibaura in the peritoneal cavity of guinea pigs which had been previously immunized with the homologous strain. The variants appeared at a rate of 63% of the leptospiras which survived in the peritoneal cavity, and the survivors' rate was 0.00005% of the inoculated organisms. The antigenicity of these variants reversed to that of the parent after 3-5 passages in liquid normal serum medium.

Animals↗

PubMed1984

[A type strain or a neotype strain of Leptospira].

A deep review of the scientific literature concerning the history of the two oldest icterohaemorrhagiae strains is given in order to promote a decision about the legitimate neotype strain on the genus Leptospira. The strain RGA was found to meet completely the requirements for a Neotype culture given by the International Code of Nomenclature of Bacteria. Its origin from a patient with Weil's disease through guinea pig passages in 1915 is well documented and its culture is unequivocally described by Ungermann in 1916. The strain was maintained in pure culture. Since more than 60 years the strain is used for comparative investigations in classification studies in all laboratories performing such tests. At contrary the history of strain Ictero I is very incomplete. The strain was claimed by Yamamoto to be one of the strain isolated by Inada and Ido in 1915 originally designated as Yamasaki. However, the statement the maintenance of these strains because of loss of virulence was discontinued, is repeatedly mentioned in some old publications of the authors. Moreover it is reported that the strain Ictero I because of contamination with a fungus was recultivated after a passage through a splenectomized mouse, i.e. the strain was not maintained in a pure culture. Beside this it is hardly understandable why has the strain not been submitted to other laboratories before 1965. The strain Ictero I was found to contain an additional thermolabile antigen not present in RGA. At present it is impossible to decide whether this property was already present in the original culture or developed only later, eventually after its mouse passage. Summarizing all these facts, it must be stated that the strain Ictero I cannot be considered to meet all the necessary requirements of its recognition as neotype culture of the Genus Leptospira.

Bacteriology↗

PubMed1983

Experimental infection with the virulent, Central-European, murine Leptospira pomona strain in the pig.

The virulent, murine Leptospira pomona strain isolated from Apodemus agrarius was used in an experimental infection of six pigs aged 4--5 months. The clinical course of the infection was inapparent, both the blood picture and the uptake of food were normal. All infected pigs produced antibodies against L. pomona at titres from 1:3 200 to 1:50 000. The reisolation of leptospires from the blood of the infected pigs was successful in one case only, and that on day two p.i. Throughout the course of our experiment, no microscopic evidence was obtained of the presence of leptospires in the blood of the infected animals. Of the six guinea pigs injected repeatedly with the urine of the infected pigs, antibodies against L. pomona were detected in two of these at titres 1:3 200 and 1:6 400. However, no direct proof was obtained of leptospires in their kidneys. Leptospires were isolated from the kidneys of two of the infected pigs, at days 10 and 21 p.i. respectively. As suggested by our results, the Central European, murine Leptospira pomona strain should be regarded as an independent biovar incapable of causing a long-term leptospiruria and, hence, apparently unable to result in an epizooty in intensive pig husbandry. According to experimental evidence, Mus musculus can be a potential reservoir of the murine L. pomona biovar in Central Europe.

Animals↗