Strain Of Leptospira Interrogans Serovar Copenhageni Research Articles

Complete Genome Sequence of a Virulent Leptospira interrogans Serovar Copenhageni Strain, Assembled with a Combination of Nanopore and Illumina Reads.

Here, we present the complete genome sequence of a highly virulent Leptospira interrogans serovar Copenhageni strain isolated from a dog with severe leptospirosis. In this work, a gapless genome draft was assembled with a combination of Nanopore and Illumina data of relatively low coverage.

Chemotaxis of leptospires to hemoglobin in relation to virulence.

A guinea pig-lethal line of Leptospira interrogans serovar copenhageni strain Shibaura, but not an avirulent line of the same strain, moved in larger numbers toward hemoglobin than toward distilled water (control) in a U-shaped polypropylene tube. L. interrogans serovar lai strains 017 and KH-1, which were also guinea pig lethal, showed a similar move to hemoglobin. No such move toward hemoglobin was shown by 14 avirulent strains of L. interrogans (with one exception) or any of the 8 strains of L. biflexa tested.

Opsonic effect of monoclonal antibodies against Leptospira interrogans serovar copenhageni

The opsonic effect of monoclonal antibodies (McAbs) against Leptospira interrogans serovar copenhageni strain Shibaura was examined in vitro using radiolabeled organisms and mouse peritoneal exudate macrophages. Four IgG McAbs (all IgG3) and 2 IgM McAbs were used, all showed different reactivities and were bound to homologous lipopolysaccharide (LPS). IgG3 McAbs at the sub-agglutinating concentration were opsonic, but the degree of the opsonic effect varied among IgG3 McAbs. Opsonization with IgG3 McAbs at the concentration showing the same level of ELISA binding showed that the highest opsonic effect was exerted by Sw-6 antibody. The other IgG3 McAbs showed a similar but lower opsonic effect. IgM McAbs, which were not opsonic at the sub-agglutinating concentration even in the presence of complement, showed opsonic effect at the agglutinating concentration.

Biological activities of Leptospiral Lipopolysaccharide

Lipopolysaccharide extracted with phenol-water from Leptospira interrogans serovar copenhageni strain Shibaura (L-LPS) showed various biological activities. In lethality for mice, L-LPS was active (LD 50, 3.4 mg/mouse) but about 12 times less potent than Escherichia coli LPS (E-LPS) per weight basis. L-LPS had pyrogenicity for rabbits, and the fever curves showed no evidence of the classical biphasic fever produced by E-LPS. In the bone marrow of mice, L-LPS caused hemorrhages and necrosis but less severe than those caused by E-LPS. Histopathologically, fresh hemorrhages were found in the intestine, spleen, lung and the other organs at 24 h after inoculation of L-LPS. Necrosis was also found in these organs and was particularly severe in mice inoculated with more than 2 mgL-LPS. Liver necrosis was found at 7th day after inoculation of L-LPS but not after inoculation of E-LPS. L-LPS had adjuvant activity just like E-LPS. L-LPS enhanced non-specific resistance to Salmonella infection and activated mouse peritoneal macrophages to kill these organisms. L-LPS was positive in limulus test just like E-LPS. These results demonstrated similarities of L-LPS and E-LPS. Some toxic effects of L-LPS were less than those of E-LPS, but some effects of L-LPS were more than those of E-LPS. L-LPS was antigenically active and the specificity was serogroup-associated. L-LPS was composed of carbohydrate (54%), lipid (12%), protein (5%). Arabinose, xylose and rhamnose were major sugars as detected by gas chromatography. 2-keto-deoxyoctanate (KDO) was not detectable.