Immunogenicity and protective efficacy of orally administered recombinant Lactobacillus plantarum expressing VP2 protein against IBDV in chicken

Maqsood, I.; Shi, W.; Wang, L.; Wang, X.; Han, B.; Zhao, H.; Nadeem, A.M.; Moshin, B.S.; Saima, K.; Jamal, S.S.; Din, M.F.; Xu, Y.; Tang, L.; Li, Y.

AIM: To develop an effective oral vaccine against the very virulent infectious bursal disease virus (vvIBDV), we generated two recombinant Lactobacillus plantarum strains (pPG612‐VP2/LP and pPG612‐T7g10‐VP2/LP, which carried the T7g10 translational enhancer) that displayed the VP2 protein on the surface, and compared the humoral and cellular immune responses against vvIBDV in chickens. METHODS AND RESULTS: We genetically engineered the L. plantarum strains pPG612‐VP2/LP and pPG612‐T7g10‐VP2/LP constitutively expressing the VP2 protein of vvIBDV. We found that the T7g10 enhancer efficiently upregulates VP2 expression in pPG612‐T7g10‐VP2/LP. Orally administered, pPG612‐T7g10‐VP2/LP exhibited significant levels of protection (87·5%) against vvIBDV in chickens, indicating improved immunogenicity. Chickens in the pPG612‐T7g10‐VP2/LP group produced higher levels of interferons (IFN‐γ) and interleukins (IL‐2 and IL‐4) than those in the pPG612‐VP2/LP group. CD8+ and CD4+ lymphocyte counts indicated greater stimulation in the pPG612‐T7g10‐VP2/LP group (13·3 and 21·0% respectively) than in the pPG612‐VP2/LP group (10·4 and 14·0% respectively). Thus, pPG612‐T7g10‐VP2/LP could induce strong humoral and cellular immune responses against vvIBDV. CONCLUSIONS: The recombinant L. plantarum that expresses pPG612‐T7g10‐VP2 is a promising candidate for oral vaccine development against vvIBDV. SIGNIFICANCE AND IMPACT OF THE STUDY: The recombinant Lactobacillus delivery system provides a promising strategy for vaccine development against vvIBDV in chickens.