A Novel Recombinant BCG Vaccine Encoding Eimeria tenella Rhomboid and Chicken IL-2 Induces Protective Immunity Against Coccidiosis

A novel recombinant Bacille Calmette-Guerin (rBCG) vaccine co-expressed Eimeria tenefia rhomboid and cytokine chicken IL-2 (chIL-2) was constructed, and its efficacy against E. tenefia challenge was observed. The rhomboid gene of E. tenefia and chIL-2 gene were subcloned into integrative expression vector pMV361, producing vaccines rBCG pMV361-rho and pMV361-rho-112. Animal experiment via intranasal and subcutaneous route in chickens was carried out to evaluate the immune efficacy of the vaccines. The results indicated that these rBCG vaccines could obviously alleviate cacal lesions and oocyst output. Intranasal immunization with pMV361-rho and pMV361-rho-IL2 elicited better protective immunity against E. tenefla than subcutaneous immunization. Splenocytes from chickens immunized with either rBCG pMV361-rho and pMV361-rho-1L2 had increased CD4+ and CD8+ cell production. Our data indicate recombinant BCG is able to impart partial protection against E. tenefia challenge and co-expression of cytokine with antigen was an effective strategy to improve vaccine immunity.