Oral immunisation with Taishan Pinus massoniana pollen polysaccharide adjuvant with recombinant Lactococcus lactis-expressing Proteus mirabilis ompA confers optimal protection in mice.

BACKGROUND: Proteus mirabilis poses a critical burden on the breeding industry, but no efficient vaccine is available for animals.

METHOD: A recombinant Lactococcus lactis expressing the ompA of P. mirabilis was used to develop a vaccine. The mucosal and systemic immune responses of the recombinant vaccine were evaluated in mice after oral immunisation. The inhibition on P. mirabilis colonisation of vaccines was also determined. Moreover, Taishan Pinus massoniana pollen polysaccharides (TPPPS) were used as adjuvants to examine the immunomodulatory effects.

RESULTS: The pure recombinant L. lactis vaccine significantly induced the production of specific IgA and IgG, IL-2, IL-4, IFN-γ, and T lymphocyte proliferation, and the immunised mice exhibited significant resistance to P. mirabilis colonisation. Notably, the TPPPS adjuvant vaccines induced higher levels of immune responses than the pure L. lactis.

CONCLUSIONS: The L. lactis as a vaccine vehicle combined with TPPPS adjuvant provides a feasible method for preventing P. mirabilis infection.