Avaliação da cinética da infecção por uma linhagem atenuada de Corynebacterium pseudotuberculosis em camundongos e caprinos

Abstract

Corynebacterium pseudotuberculosis is a Gram-positive, facultative intracellular pathogen that causes Caseous Lymphadenitis (CLA) in goats and sheep. CLA consists of abscesses development in superficial and internal lymph nodes. Infection with C. pseudotuberculosis represents a significant economic impact in sheep and goat herd worldwide. Until now, there is no efficient tool for the immune prophylaxis of the disease. Thus, it is need the development of new alternatives against CLA. Through random mutagenesis using TnFuZ, it was obtained an attenuated strain of C. pseudotuberculosis, CP13, which presented promising results in mice vaccination trials. Firstly, theaim of this study was to evaluate the humoral and cellular immune responses in BALB/c mice following one intraperinotenal inoculation with the live mutant strain of C. pseudotuberculosis. The induced responses were assessed over a twenty-eight days period and mice were challenged with a virulent strain. Titers of IgG1 and IgG2a in serum were determined and cellular immune response were evaluated by quantification of TNF-alfa, IL-10, IL-4, IFN-gamma by enzyme linkedimmunosorbent assay in splenocyted. Secondly, a pilot test assessed the potential of this vaccine strain in reducing injuries caused by LC in goats. Twenty-three young goats received one or two doses of the recombinant strain, and an experimental infection with virulent strain MIC-6 of C. pseudotuberculosis were done 30 days post-immunization. The Th1 immune response profile characteristic induced by this recombinant strain in mice is probably responsible for the protection observed. Also the observations in goats revealed that treatment with two doses can be more effective in reducing injuries in lymph nodes.