Efeito da suplementação com Hermetia illucens na resposta imune e proteção contra linfadenite caseosa em camundongos vacinados com rNanH

Abstract

Caseous lymphadenitis (CLA) is a chronic disease that affects sheep and goats worldwide and is caused by the gram-positive bacterium Corynebacterium pseudotuberculosis, characterized by the formation of abscesses in lymph nodes. Even established treatment methods are still considered ineffective and expensive, and although vaccination is the best strategy for preventing and controlling CLA, available commercial vaccines have low efficacy and adverse reactions, making it important to search for new targets and vaccine formulations that are safer and more economical. Along with vaccination, the diet based on Hermetia illucens presented several bioactive components with immunomodulatory capacity. The present study demonstrates the concentration of specific antibodies after vaccination with recombinant NanH protein in conjunction with a supplemented feed. For this, the rNanH protein was expressed in E. coli, purified, and characterized by Western blot. For in vivo experimentation 40 Balb/c mice were used, divided into 4 groups, in which group 1 (G1) and group 2 (G2) received 200 µL of saline solution while group 3 (G3) and group 4 (G4) received two doses of 200 µL containing 50 µg of rNanH and 7.5 µg of saponin as an adjuvant. G2 and G4 were under constant supplementation with feed. After 21 days of the second dose, the animals were challenged with the pathogenic strain of C. pseudotuberculosis MIC-6. Blood samples were collected for indirect ELISA. To automate statistical analysis, a software called CLARA was developed. G4 had high levels of IgG1 and a decrease in IgG2a when compared to G3. G3 and G4 survival rates were 80% and 70%, respectively, while G2 showed an increase in survival compared to G1. Even with a Th2-type induction, the supplemented feed appears to have contributed to an improvement in the innate immune response. For future perspectives, the production of pro-inflammatory cytokines and other immunomodulatory applications are expected to be analyzed.