Avaliação de uma vacina recombinante de subunidade formulada com a associação das proteínas rPLD, rCP01850 e rCP40 de Corynebacterium pseudotuberculosis

Abstract

Caseous lymphadenitis (CLA) is an infectious disease with worldwide incidence, and it mainly affects goats and sheep and its etiological agent is the bacterium Corynebacterium pseudotuberculosis. By causing the formation of abscesses in these animals' superficial lymph nodes and internal organs, it generates an economic impact on sheep and goat farming. Currently, commercial vaccines do not provide effective protection and still show many adverse effects. Taking this into consideration, using recombinant protein production technology to develop subunit vaccine formulations is presented as a suitable approach since it leads to greater safety levels. In addition, using antigens in an association can be another strategy when seeking better protection levels. Two important vaccine targets produced by the pathogen have already been characterized: the PLD and CP40 proteins. In addition, the rCP01850 protein has already been shown to stimulate the production of humoral response and is also useful for immunodiagnostics. In the present study, to evaluate the association of purified rPLD, rCP01850 and rCP40 proteins in a vaccine formulation, five groups containing 10 Balb/c mice were established as follows G1 - 0.9% saline solution, G2 - rPLD/Al(OH) 3 , G3 - rCP01850/ Al(OH) 3 , G4 - rCP40/ Al(OH) 3 , and G5 - rPLD, rCP01850 and rCP40/ Al(OH) 3 . All groups were immunized with two vaccine doses within a 21-day interval and challenged on day 42 with 10 4 CFU of the virulent MIC-6 strain of C. pseudotuberculosis. The protection rates after the challenge were 30% (G3), 80% (G2 and G4), and 100% (G5). All animals in the control group reached the endpoint. The multiple protein-associated vaccine formulation (G5) induced the production of total IgG, IgG 1, and IgG2a antibodies against rPLD, rCP01850 and rCP40 proteins, however, this production did not show statistical difference when compared with the individual groups (G2, G3 and G4). However, it should be considered that in G5 all animals survived the challenge with the virulent strain, which suggests that another type of immune response, possibly the cellular response, is involved in the survival of these animals. Thus, considering that in the G5 group, immunization resulted in total survival of these animals, the association of rPLD proteins, rCP01850 and rCP40, should be considered a promising strategy for CLA as well as being further evaluated more thoroughly.