[show abstract][hide abstract] ABSTRACT: Leptospirosis is one of the most widespread zoonosis in the world. The development of a recombinant leptospira vaccine remains a challenge. In this study, we cloned the Leptospira interrogans open reading frame (ORF) coding the external membrane protein LipL32, an immunodominant antigen found in all pathogenic leptospira, downstream of the highly immunogenic cholera toxin B subunit (CTB) ORF. Expression and assembly of the CTB-LipL32 fusion protein into oligomeric structures of pentameric size were observed in soluble fractions by Western blot analysis. The CTB-LipL32 protein demonstrated strong affinity for monosialotetrahexosylgaglioside (GM1-ganglioside) in an enzyme-linked immunosorbent assay (ELISA), suggesting that the antigenic sites for binding and proper folding of the pentameric CTB structure were conserved. Furthermore, antisera against LipL32 also recognized the CTB-LipL32 fusion protein, suggesting that LipL32 also conserved its antigenic sites, a fact confirmed by an ELISA assay showing soluble CTB-LipL32 recognition by sera from convalescent patients. In addition, soluble CTB-LipL32 generated higher specific titers in mice immunized without external adjuvant than co-administration of CTB with LipL32. The data presented here provide support for CTB-LipL32 as a promising antigen for use in the control and study of leptospirosis.
Current Microbiology 02/2011; 62(2):526-31. · 1.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: With the aim to study if selenium (Se) deficiency affects the basal frequency and cardiac response to isoproterenol (ISO), mice were fed a Se-deficient diet (Se-) or the same diet supplemented with 0.2 ppm Se as sodium selenite (Se+) for 4 wk. Atria frequency, cyclic AMP (cAMP) accumulation, nitric oxide synthase (NOS) activity, and beta-adrenoceptor-binding assay were then examined. Results showed that Se-mice have both a reduction in atria frequency as well as in cAMP content but higher NOS activity levels either at basal or after ISO stimulation. These differences were suppressed by feeding Se-mice with a Se-supplemented diet for 1 wk or by inhibition of inducible nitric oxide synthase (iNOS). Alterations observed after ISO stimulation in atria of Se-mice were not related to a beta-adrenoceptor expression modification because specific radioligand-binding parameters in cardiac membranes from Se-mice and Se+ mice were similar. The reduced response on rate and cAMP in atria from Se-mice to direct adenylate cyclase (AC) stimulation by forskolin and the shifted upward levels present in 2-amino-4-methylpyridine-treated Se-mice is in agreement with a negative crosstalk between iNOS activity and AC activity in Se-mice.
Biological Trace Element Research 02/2007; 117(1-3):127-38. · 1.31 Impact Factor