Proteínas recombinantes PLD e CP40 associadas ou fusionadas como imunógenos na imunoprofilaxia da Linfadenite Caseosa em ovinos

Abstract

Caseous lymphadenitis is an infectious disease caused by the bacterium Corynebacterium pseudotuberculosis, being associated with significant economic impacts on goat and sheep farming. The treatment of the disease is not efficient and does not prevent relapses, and there is still no truly efficient immunoprophylaxis for both goats and sheep. Thus, the present work addresses two proposals for vaccine formulations containing the recombinant proteins PLD and CP40. The two proteins were evaluated as an association or in a fused form (added with maltose binding protein - MBP) using bioinformatics tools, and subsequently expressed. Twenty-seven sheep were divided into 3 groups, which were inoculated twice with separate rPLD and rCP40 proteins (G3), the same proteins fused and added with MBP (G2), and a control group (G1). A challenge with a virulent strain of C. pseudotuberculosis was performed 15 days after the second dose. Over 12 weeks, the animals were clinically evaluated, and the surface granulomas that appeared were removed for microbiological analysis. Monitoring of antibody production and analysis of specific production of IFN-γ and IL-4 were also performed. At the end of the experimental period, the animals were euthanized and necropsied to evaluate internal lesions. The group immunized with the fused proteins, when compared to the control group, had a reduction in the number of lesions of 71.42%, and the one immunized with the associated proteins 90.4%, with the latter group showing a higher production of antibodies and cytokines. 77.7% of the animals immunized with the association of recombinant proteins developed lesions, while this value was 33.3% for the fusion protein group; all sheep in the control group developed lesions. It can be concluded that the responses obtained by the vaccine proposal with associated proteins is viable in the immunoprophylaxis of caseous lymphadenitis in small ruminants, since it was able to induce immunoprotection and production of specific cytokines.