Construction and immunological evaluation of recombinant Lactobacillus plantarum expressing HN of Newcastle disease virus and DC- targeting peptide fusion protein

• We design a new fusion protein composed of NDV HN protein and a 12-mer DC cells targeting peptide (DCpep).
• Lactobacillus plantarum with an inducible vector pSIP409 is used to deliver the fusion protein to chicken.
• Results show that the inclusion of DCpep significantly increased the production of SIgA and CD4+ cells.

Newcastle disease virus (NDV) has been considered as one of the most severe threats to poultry industry. In this study, we constructed a series of food grade recombinant Lactobacillus plantarum (L. plantarum) strains (RLP) synthesizing either virus hemagglutinin–neuraminidase protein (HN) alone or HN fused with DC cells targeting peptides (DCpep), named RLP(pSIP409-HN) and RLP (pSIP409-HN-DCpep), respectively. The immune responses and protective efficacy were then evaluated in chickens. Results showed that the presence of DCpep in RLP (pSIP409-HN-DCpep) group significantly increased the production of secretory immunoglobulin A (SIgA) in intestines and the percentages of CD3+CD4+ T cells in spleen and peripheral blood leukocytes (P < 0.05) compared to chickens immunized with RLP (pSIP409-HN). In addition, the similar enhancement effects were also observed with regard to trachea SIgA, T lymphocytes proliferation and survival rates after NDV challenge, even without significant statics differences. The results demonstrated the possibility to take use of DCpep as an immune adjuvant in the design of NDV vaccine.