Co-administration of recombinant chicken IL-7 or chicken NK-lysin peptide 2 increases efficacy of Eimeria tenella elongation factor-1α in Eimeria maxima infected chicken

Abstract

Abstract This study was conducted to improve the efficacy of recombinant Eimeria tenella elongation factor-1α (EF-1α) antigen by co-administrating recombinant chicken IL-7 or chicken NK-lysin peptide 2 in Eimeria maxima-challenged chickens. On day 4, birds were administered with following five groups: (CON) control birds without Eimeria infection, (NC) sterile PBS solution plus adjuvant (ISA 78 VG), (COM 1) 100 μg of recombinant EF-1α plus ISA 78 VG, (COM 2) COM 1 component plus 1 μg of recombinant chIL-7, and (COM 3) COM 2 component plus 5 μg of cNK2 peptide. One week after, the boosting immunization were administrated with same concentration of components as the primary immunization. All birds except CON were orally inoculated with E. maxima (1.0 × 104 oocysts/bird) on day 19. Animal experiment demonstrated that the birds immunized with recombinant EF-1α showed greater serum anti EF-1α level, and co-administration of recombinant chIL-7 increased the level of IL-7 in serum. Vaccination of COM 2 mitigated intestinal lesion formation at 6 days post-infection (dpi) and increased body weight at 6 dpi and 9 dpi. Vaccination of COM 3 reduced fecal oocyst shedding compared with NC. E. maxima infection up-regulated expression level of jejunal proinflammatory cytokines (IL-β, IL-17F) and type I cytokines (IFN-γ and IL-10), and those expression levels were decreased by administration of COM 1, COM 2 or COM 3. Down-regulated expression of tight junction (TJ) protein (Jam2 and Occludin) by E. maxima challenge were increased by COM 2or COM 3, respectively. Overall animal experiment results demonstrated a potential effect that co-administration of recombinant IL-7 or cNK-2 peptide can increase the efficacy of recombinant EF-1α in E. maxima-infected chicken. Funding was partly supported by ARS CRIS 8042-32000-107-00D, NIFA SBIR 2015-33610-23499, and NIFA SBIR 2016-33610-25686.