Recombinant Lactococcus lactis co-expressing dendritic cell target peptide and E. tenella 3-1E protein: immune response and efficacy against homologous challenge

In the present study, recombinant L. lactis NZ9000 displaying anchored dendritic cell-targeting peptide (DCpep) and E. tenella 3-1E protein was constructed. Chickens were orally immunized with the recombinant lactococci for three times at 2-week intervals. After three immunizations, chickens were challenged with E. tenella sporulated oocyst, and the immune response and protective efficacy were evaluated. The finding from animal experiments showed recombinant lactococci expressing anchored DCpep-3-1E protein elicited higher levels of 3-1E specific serum IgG and secretory IgA (sIgA) in caecal lavage, higher proportions of CD4+ and CD8 alpha+ cells in peripheral blood, and higher mRNA expression levels of IL-2 and IFN-gamma in the spleen compared to 3-1E-expressing lactococci, and hence offered obvious protective efficacy against homologous challenge. The present work demonstrated that cell surface-displayed target protein and immune enhancers in lactococci may be a promising approach to enhance immunity and immune efficacy against pathogen infection.