Leptospirosis is a zoonotic disease caused by pathogenic spirochetes from the genus Leptospira, which includes 20 species and more than 300 serovars. Canines are important hosts of pathogenic leptospires and can transmit the pathogen to humans via infected urine. Here, we report the phenotypic and molecular characterization of Leptospira interrogans isolated from Canis familiaris in Southern Brazil. The isolated strain was characterized by variable-number tandem-repeats analysis as L. interrogans, serogroup Icterohaemorrhagiae. In addition, the isolate was recognized by antibodies from human and canine serum samples previously tested by microscopic agglutination test. Ultimately, the expression of membrane-associated antigens (LipL32 and leptospiral immunoglobulin-like proteins) from pathogenic leptospires using monoclonal antibodies was detected by indirect immunofluorescence assay. In conclusion, identification of new strains of Leptospira can help in the diagnosis and control of leptospirosis.
The successful production of new, safe, and effective vaccines that generate immunological memory is directly related to adjuvant feature, which is responsible for increasing and/or modulating the immune response. Several compounds display adjuvant activity, including carbohydrates. These compounds play important roles in the immune response, as well as having biocompatible properties in vaccine formulations. One such carbohydrate is xanthan gum, a polysaccharide that is produced by the plant-pathogenic bacterium Xanthomonas spp., which has adjuvant attributes. This study evaluated the immune response induced by xanthan gum associated with ovalbumin in BALB/c mice, which were subcutaneously immunized, in terms of antibody production (IgG1, IgG2a, IgG2b, and IgG3), and assessed the levels of IFN-γ in the splenocyte culture using indirect ELISA. Furthermore, we investigated in vitro cytotoxicity of xanthan in the embryo fibroblasts cell line of the NIH/3T3 mouse by MTT assay and propidium iodide uptake assay. The mice immunized with ovalbumin plus xanthan gum exhibited higher antibody IgG1 responses than control groups. Furthermore, the xanthan polysaccharide was capable of increasing the immunogenicity of antigens by producing IFN-γ and did not exhibit cytotoxicity effects in NIH/3T3 mouse fibroblast cells, considered a promising candidate for vaccine adjuvant.
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