Avian coccidiosis causes significant economic losses on the global poultry breeding industry. Exploration of new concept vaccines against coccidiosis has gradually become a research hotspot. In this study, an Enterococcus faecalis strain (MDXEF-1) showing excellent performance isolated from chicken intestinal tract was used as vector to delivery Eimeria target protein. The plasmid pTX8048-SP-DCpep-NAΔ3-1E-CWA harboring dendritic cell-targeting peptide (DCpep) fusion with E. tenellaNAΔ3-1E gene (3-1E protein coding gene without start codon ATG and terminator codon TAA) was electrotransformed into MDXEF-1 to generate recombinant bacteria MDXEF-1/pTX8048-SP-DCpep-NAΔ3-1E-CWA in which NAΔ3-1E protein was c... More
Avian coccidiosis causes significant economic losses on the global poultry breeding industry. Exploration of new concept vaccines against coccidiosis has gradually become a research hotspot. In this study, an Enterococcus faecalis strain (MDXEF-1) showing excellent performance isolated from chicken intestinal tract was used as vector to delivery Eimeria target protein. The plasmid pTX8048-SP-DCpep-NAΔ3-1E-CWA harboring dendritic cell-targeting peptide (DCpep) fusion with E. tenellaNAΔ3-1E gene (3-1E protein coding gene without start codon ATG and terminator codon TAA) was electrotransformed into MDXEF-1 to generate recombinant bacteria MDXEF-1/pTX8048-SP-DCpep-NAΔ3-1E-CWA in which NAΔ3-1E protein was covalently anchored to the surface of bacteria cells by cell wall anchor (CWA) sequence. The expression of target fusion protein DCpep-NAΔ3-1E-CWA was detected by Western blot. Each chicken was immunized three times at two-week intervals with live E. faecalis expressing DCpep-NAΔ3-1E fusion protein (DCpep-NAΔ3-1E group), live E. faecalis expressing NAΔ3-1E protein (NAΔ3-1E group), live E. faecalis containing empty vector only. The three immunized groups were then challenged with homologous E. tenella sporulated oocyst after immunizations, and the immune response and protective efficacy in each group were evaluated. The results showed that serum IgG levels, secretory IgA (sIgA) levels in cecal lavage, proportion of CD4+ and CD8α+ cells in peripheral blood, and mRNA expression levels of IL-2 and IFN-γ in spleen were significantly higher in chickens in DCpep-NAΔ3-1E group than in NAΔ3-1E group (P < 0.05). Oral immunization to chickens with live E. faecalis expressing DCpep-NAΔ3-1E offered more protective efficacy against homologous challenge including significant improved body weight gain (BWG), increased oocyst decrease ratio, reduced average lesion scores in cecum compared to chickens with live E. faecalis expressing NAΔ3-1E protein. These results suggest that recombinant E. faecalis expressing dendritic cell-targeting peptide fusion with E. tenella 3-1E protein could be a potential approach for prevention of Eimeria infection.
