Leptospira borgpetersenii Leucine-Rich Repeat Proteins Provide Strong Protective Efficacy as Novel Leptospiral Vaccine Candidates.

Leucine-rich repeat (LRR) proteins are advocated for being assessed in vaccine development. Leptospiral LRR proteins were identified recently in silico from the genome of Leptospira borgpetersenii serogroup Sejroe, the seroprevalence of leptospiral infections of cattle in Thailand. Two LRR recombinant proteins, rKU_Sej_LRR_2012M (2012) and rhKU_Sej_LRR_2271 (2271), containing predicted immunogenic epitopes, were investigated for their cross-protective efficacies in an acute leptospirosis model with heterologous Leptospira serovar Pomona, though, strains from serogroup Sejroe are host-adapted to bovine, leading to chronic disease. Since serovar Pomona is frequently reported as seropositive in cattle, buffaloes, pigs, and dogs in Thailand and causes acute and severe leptospirosis in cattle by incidental infection, the serogroup Sejroe LRR proteins were evaluated for their cross-protective immunity. The protective efficacies were 37.5%, 50.0%, and 75.0% based on the survival rate for the control, 2012, and 2271 groups, respectively. Sera from 2012-immunized hamsters showed weak bactericidal action compared to sera from 2271-immunized hamsters (p < 0.05). Therefore, bacterial tissue clearances, inflammatory responses, and humoral and cell-mediated immune (HMI and CMI) responses were evaluated only in 2271-immunized hamsters challenged with virulent L. interrogans serovar Pomona. The 2271 protein induced prompt humoral immune responses (p < 0.05) and leptospiral tissue clearance, reducing tissue inflammation in immunized hamsters. In addition, protein 2271 and its immunogenic peptides stimulated splenocyte lymphoproliferation and stimulated both HMI and CMI responses by activating Th1 and Th2 cytokine gene expression in vaccinated hamsters. Our data suggest that the immunogenic potential renders rhKU_Sej_LRR_2271 protein a promising candidate for the development of a novel cross-protective vaccine against animal leptospirosis.

Amyloid beta-peptide decreases neuronal glucose uptake despite causing increase in GLUT3 mRNA transcription and GLUT3 translocation to the plasma membrane.

Amyloid beta-peptide (Abeta) has been shown to impair glucose uptake in cultured hippocampal neurons and shortens their survival time. Abeta appears to inhibit neuronal glucose uptake by activating Gs-coupled receptors and the cAMP-PKA system. In this study, Abeta inhibition of neuronal glucose uptake was studied by assaying translocation of glucose transporter isoform GLUT3, transcription of GLUT3 mRNA, and fusion of GLUT3-containing vesicles with the plasma membrane. Cultured hippocampal neurons exposed to 10 microM Abeta25-35 or Abeta1-40 for 3 or 24 h showed a significant decrease in glucose uptake. To assess the regulatory role of Abeta on neuronal glucose uptake, translocation of GLUT3 from the cytosol to the plasma membrane was studied by the plasma membrane lawn assay and transcription of GLUT3 mRNA by in situ hybridization. In spite of a decrease in glucose uptake, Abeta25-35 and Abeta1-40 (10 microM) markedly promoted GLUT3 translocation to the plasma membrane by 30 min. Abeta25-35 also up-regulated transcription of GLUT3 mRNA by 12 h. High extracellular K(+) increased immunolabeling of the exofacial (i.e., extracellular) epitope of GLUT3 at the plasma membrane and Abeta25-35 inhibited this increase. Based on these data we propose that Abeta increases translocation of GLUT3-containing vesicles, but inhibits their fusion with the plasma membrane.