Oral vaccination with invasive Lactobacillus plantarum delivered nucleic acid vaccine co-expressing SS1 and murine interleukin-4 elicits protective immunity against Trichinella spiralis in BALB/c mice.

Trichinellosis is a foodborne zoonosis caused by Trichinella spiralis (T. spiralis) that not only causes considerable economic losses for the global pig breeding and food industries, but also seriously threats the health of human. Therefore, it is very necessary to develop an effective vaccine to prevent trichinellosis. In this study, the invasive Lactobacillus plantarum (L. plantarum) expressing fibronectin-binding protein A (FnBPA) was served as a live bacterial vector to deliver DNA to the host to produce a novel oral DNA vaccine. Co-expressing T. spiralis SS1 and murine interleukin-4 (mIL-4) of DNA vaccine were constructed and subsequently delivered to intestinal epithelial cells via invasive L. plantarum. At 10 days after the third immunization, the experimental mice were challenged with 350 T. spiralis infective larvae. The results found that the mice orally vaccinated with invasive L. plantarum harboring pValac-SS1/pSIP409-FnBPA not only stimulated the production of anti-SS1-specific IgG, Th1/Th2 cell cytokines, and secreted(s) IgA but also decreased worm burden and intestinal damage. However, the mice inoculated with invasive L. plantarum co-expressing SS1 and mIL-4 (pValac-SS1-IL-4/pSIP409-FnBPA) induced the highest protective immune response against T. spiralis infection. The DNA vaccine delivered by invasive L. plantarum provides a novel idea for the prevention of T. spiralis infection.

Lactobacillus plantarum surface-displayed ASFV (p54) with porcine IL-21 generally stimulates protective immune responses in mice.

African classical swine fever virus (ASFV) has spread seriously around the world and has dealt with a heavy blow to the pig breeding industry due to the lack of vaccines. In this study, we produced recombinant Lactobacillus plantarum (L. plantarum) expressing an ASFV p54 and porcine IL-21 (pIL-21) fusion protein and evaluated the immune effect of NC8-pSIP409-pgsA'-p54-pIL-21 in a mouse model. First, we verified that the ASFV p54 protein and p54-pIL-21 fusion protein were anchored on the surface of L. plantarum NC8 by flow cytometry, immunofluorescence and Western blotting. Then, the results were verified by flow cytometry, ELISA and MTT assays. Mouse-specific humoral immunity and mucosal and T cell-mediated immune responses were induced by recombinant L. plantarum. The results of feeding mice recombinant L. plantarum showed that the levels of serum IgG and mucosal secreted IgA (SIgA), the number of CD4 and CD8 T cells, and the expression of IFN-γ in CD4 and CD8 T cells increased significantly, and lymphocyte proliferation occurred under stimulation with the ASFV p54 protein. Our data lay a foundation for the development of oral vaccines against ASFV in the future.