A genômica como ferramenta para seleção de alvos contra a Linfadenite Caseosa

Abstract

Between the years of 2009 and 2011, the genomes of strains 1002, C231, I19, PAT10 and FRC41 of Corynebacterium pseudotuberculosis were deposited at the site of NCBI. We used pangenomics allied to the prediction of exported proteins on these five genomes as the first step of Reverse Vaccinology (RV), a methodology that aims at finding vaccines starting from in silico predictions of full genomes rather than isolated antigens by traditional approaches. Among all five strains, strains 1002 and C231, that infect goats and sheep respectively, were adopted as models. Although C. pseudotuberculosis also causes other diseases in animals, such as horses and cattle, the selection of strains 1002 and C231 as models was based on the importance of the disease caseous lymphadenitis (CLA) and also due to the high similarity degree between these genomes. CLA is a worldwide distributed chronic infectious disease associated with considerable economic losses. The absence of effective vaccines and diagnostics against CLA boosted research on the molecular mechanisms of pathogenesis of this bacterium. To predicted in silico exported proteins into five C. pseudotuberculosis strains, a combination of exportation motifs predicting programs were arranged in a pipeline, a schema were a program's processing result serves as initial parameter to initiate the processing of the other programs. We obtained 750 proteins predicted as secreted, out of approximately 17.000 proteins of the five genomes. Among these results, 139 and 149 were predicted as secreted proteins in strains 1002 and C231 respectively. Within these predictions, there were 87 and 77 proteins confirmed as secreted by proteomics studies in the strains 1002 and C231 respectively. Within these proteins, 55 are common to both model strains. The results obtained for the model strains were considered valid also for the other strains of this species. in silico analysis of the predicted immunogenic potential of the exoproteome, allied with the experimentally proven exoproteome demonstrated fifteen proteins owning a differential predicted epitope's concentration per protein's mature portion. Among these fifteen proteins, four stood out in terms of their in silico immunogenic potential and are currently under experimental tests in the search for vaccines, drugs and diagnosis against CLA.