Anti-erythrocyte IgG in hamsters with acute experimental infection by Leptospira interrogans serovar Canicola.

The aim of this study was to evaluate the behavior of erythrocyte and platelet, as immunological markers, as well as evaluate the involvement of these factors in hemolytic and hemorrhagic reactions in hamsters experimentally infected by Leptospira interrogans Serovar Canicola. Our experimental design was composed by two randomized groups: Infected Group (IG) (n = 12) and control group (CG) (n = 6). Ninety-six hours after the inoculation, the presence of immunoglobulins (IgG and IgM) and complement C3 levels, related to erythrocytes and platelets, was assessed. Platelet's microparticles marked by CD61, reticulocytes and reticulated platelets were also quantified. Additionally, fibrinogen, prothrombin time, partially activated thromboplastin time and sera levels of IgG and IgM were assessed. Our results showed that levels of platelet decreased in IG (P < 0.001); as well as, there was presence of IgG and C3 associated with erythrocyte surface in the infected animals (P < 0.01, P < 0.05, respectively). Levels of prothrombin time and Activated Partial Thromboplastin Time were increased, while fibrinogen level was decreased (P < 0.01) in IG. CD61 microparticles were higher (P < 0.05) in IG due to platelet activation. Thus, it was established a positive correlation (P < 0.01) between platelets count and fibrinogen (Figure 3, R = 0.84, P < 0.001). Therefore, the platelet consumption component was preponderant in relation to autoimmune causes. Finally, regarding the erythrocytes, the autoimmune component played an important role, did not causing hemolytic reaction in this acute experimental time.

Evaluation of the Use of Selective PCR Amplification of LPS Biosynthesis Genes for Molecular Typing of Leptospiraat the Serovar Level

Leptospirosis is an important epidemic zoonosis worldwide. Currently, there are more than 250 Leptospira pathogenic serovars known that can potentially infect humans. Conventional classification of leptospires with the serovar as the basic taxon, based on serological recognition of lipopolysaccharide (LPS) composition does not correlate well with species determination, based on general genomicfeatures. Here, we investigate the selective amplification of polymorphic regions from the LPS biosynthesis loci (rfb) as a potential tool for serovar typing of Leptospira interrogans species. Eight pairs of primers were designed to target six ORFs from the rfb operon with varying levels of sequence polymorphism. They were tested both separately and multiplexed. Half of these primer pairs produced serovar-specific amplicons, allowing the identification of some specific serovars and also groups of serovars. It was shown that the serovar classification of Leptospira can be accessed by selective amplification of rfb operons in some cases, which may permit a parallel between the serological and the genomic classifications of Leptospira. As a conclusion, the selective amplification of rfb generated promising and already useful results, but it appears necessary to characterize a larger variety of Leptospira genomes or rfb operons to fully develop this method.

The maintenance of challenge strains used in the potency test for canine leptospira vaccines.

The challenge test for leptospira vaccines required by most licensing authorities is difficult to standardise and unreliable. One of the main contributory factors to this, is the difficulty in maintaining the virulence of the challenge strain. This paper describes work carried out to assess the practicality of storing challenge strains of Leptospira canicola and Leptospira icterohaemorrhagiae in liquid nitrogen. The effects of different concentrations of glycerol and dimethyl sulphoxide on the recovery of virulent and avirulent strains of Leptospira canicola and Leptospira icterohaemorrhagiae were investigated. Concentrations of cryopreservant above 5% increased the time taken for the leptospires to grow after recovery from vials stored in liquid nitrogen. In addition, the virulence of five challenge strains were shown to be little affected after 18 passages in vitro.

Clinical, bacteriologic and histopathologic studies on induced leptospirosis in stray dog pups.

Eighteen 8-12 days old stray dog (canis familiaris mongrel) pups of either sex; 6 pups each in test groups and control group were infected with lepotspiral serovars autumnalis and canicola. The experimental animals, clinical, bacteriologic and histopathologic kinetics were observed. Both the serovars had evoked typical clinical manifestations. Leptospiraemia could be demonstratedin between the post inoculation (PI) days 1 & 5. Leptospiruria commensed in between the PI days 5 & 7 and lasted throughout the study period. Histopathologic study did not reveal any marked pathologic changes except hydropic changes in the liver of both the test groups.

[Characteristics of the interaction of Leptospira with the host organism in the infectious process in golden hamsters]. / Osobennosti vzaimodeistviia leptospir s organizmom khoziaina pri infektsionnom protsesse u zolotistykh khomiakov.

The comparative evaluation of the interaction of L. icterohaemorrhagiae strain P, L. canicola strain CL and L. hebdomadis strain 650 with golden hamster liver and kidney cells is presented. Three variants of the course of Leptospira infection have been distinguished: (1) the hepato-renal (icteric) variant, caused by the adhesion of leptospires to liver cells with the colonization of their surface and the disaggregation of liver-cell complexes and by the accumulation of leptospires in the kidney interstice; as a consequence, parenchymatous hepatitis and nephroso-nephritis develop, which lead to the death of animals; (2) the renal (anicteric) variant, characterized by the absence of the infective agent and lesions in the liver, by adhesion of leptospires to and their colonization of the nephrothelium of the proximal convoluted tubules of the kidneys; in this case some of the animals die because of renal insufficiency and shock, while in the surviving animals prolonged carrier state develops; (3) the intermediate variant, characterized by the initial process of leptospiral adhesion and colonization in the liver and its subsequent progress in the kidneys.

Leptospiral attachment to cultured cells.

Each virulent strain of copenhageni, canicola and pomona of Leptospira interrogans attached effectively to MDCK cells and primary dog kidney cells, while the avirulent or less virulent line of the same strain and avirulent strains belonging to the same serovars and the avirulent reference strains of other serovars did not. Inhibition of the attachment of the virulent copenhageni to MDCK cells was found in the presence of the homologous immunoglobulin G Fab fragment. Strains of L. biflexa attached to the animal cells, but they differed from those of virulent L. interrogans in their capability to attach to glass.

Serological and ecological study of the genus Leptospira in Jamaica

In a serological and ecological study of the genus Leptospira in Jamaica, 535 sera from three species of livestock animals, bovine, porcine and caprine were serologically tested by the microscopic agglutination technique using live leptospiral antigens. Of the number tested, 316 (59.06 percent) were reactive with titers equalling or greater than 1:100. A total of six serotypes were identified and representative serovars were as follows:- jules (serogroup Hebdomadis) 257 (51.92 percent); icterohemorrhagiae (serogroup Ictero-hemorrhagiae) 140 (28.07 percent); autumnalis (serogroup Autumnalis) 41 (8.3 percent); canicola (serogroup Canicola) 30 (6.06 percent); pomona (serogroup Pomona) 25 (5.19 percent) and abramis (serogroup Pyrogenes) 2 (0.4 percent). The porcine species recorded the highest percentage of reactive sera (65.5 percent) and the caprine the lowest (38.9 percent). The widest distribution of serotypes occurred in pigs. A comparison of the parishes showed that the positive sera from Portland (80.9 percent) and Westmoreland (71.6 percent) topped others and St. Andrew had the lowest 11.0 percent. For the ecological study, 22 soil and 25 water samples collected from five selected livestock farms in the island were cultured initially in enrichment artificial medium (Ellinghausen and McCullough semi-solid), ESS, incorporating 5-fluorouracil, for the isolation of leptospires. A total of 23 (48.9 percent) isolates were obtained:- 16 (72.7 percent) from the soil samples and 7 (28 percent) from the water samples. One water isolate was lost and the 22 parent isolates were subsequently inoculated into weanling hamsters. The kidney tissues and heartblood of the inoculated hamsters on culture yielded 8 leptospiral isolates and the microscopic agglutination test of the sera of inoculated hamsters gave 9 reactive results. There was no positive results either from culture or serological test of the control (uninoculated) hamsters. The investigations revealed that the constituents of Jamaican soil, the heavy rainfall and the various environmental factors are ideal for the survival and distribution of leptospires in the island. Flooding helps to spark off epizootic outbreaks and the leptospiral serotypes mentioned earlier are enzootic and endemic in Jamaica. The predominant serotypes are jules and icterohemorrhagiae. People at high risk are the livestock attendants and milkers. The epidemiological importance of the serotypes identified and suggested means of dealing with their adverse effects are discussed (AU)

Human leptospirosis.

Human leptospirosis is a subject of increasing interest. Although this disease was frequently associated with individuals whose occupation or geographic location placed them in close proximity to wild animals or farm animals, recent cases have been particularly prevalent in young children and adolescents in urban and suburban America. Many of the recent cases have been acquired from household pets, particularly from dogs or hamsters. In particular, healthy dogs who have been immunized with leptospiral organisms, thereby creating a significant risk for their owners. This article will review the pathophysiology, clincal manifestations, laboratory diagnosis, treatment, and prevention of leptospirosis in the modern era, with particular emphasis on a more complete understanding of the epidemiology of this disorder.

Cultivation of parasitic leptospires: effect of pyruvate.

Sodium pyruvate (100 mug/ml) is a useful addition to the Tween 80-albumin medium for the cultivation of parasitic serotypes. It is most effective in promoting growth from small inocula and growth of the nutritionally fastidious serotypes.

Studies on the susceptibility of water buffaloes to Leptospira.

Eight mature farming type, Taiwan, water buffaloes were inoculate with L. australis A while six received L. canicola. Before inoculation all animals were negative to the microscopic-agglutination test (agglutinationlysis test) using the above species as antigen. No sign of clinical leptospirosis was observed although four animals developed temperatures. Cultures made from buffalo blood, kidneys and urine and from blood of guinea pigs inoculated with kidney emulsion and urine from the inoculated buffalo were all negative for leptospiral organisms. Blood samples drawn from the water buffalo 2, 3 and 4 weeks post inoculation were negative to the microscopic-agglutination test except for one animal. Blood from the animal taken two weeks post-inoculation was positive at 1:100 dilution with L. australis A antigen but that taken at 3 and 4 weeks was negative.