[Co-expression of CSFV T cell epitope E290 peptide and PPV VP2 protein in Lactobacillus casei and determination of specific antibodies in immunized mice].

Lactobacillus casei strain 393 was selected as an antigen delivery vehicle for the development of oral vaccine to express recombinant classical swine fever virus (CSFV) T cell epitope E290 peptide and porcine parvovirus (PPV) VP2 protein. The recombinant genes encoding CSFV T cell epitope E290 peptide and PPV VP2 protein, respectively, were cloned into the secretion expression vector pPG, and then the pPG-VP2-E290 was electrotransformed into L. casei 393 giving rise to recombinant strain pPG-VP2-E290/L. casei 393. The recombinant L. casei 393 was induced by 2% lactose in MRS and about 70kDa protein was detected with SDS-PAGE in induced recombinant strain and culture supernatants. The result of Western blot indicated that the expressed protein possessed the antigenic specificity same as the native virus protein. The indirect ELISA test also indicated that the interest protein was expressed and secreted from the recombinant strain. Specific anti-PPV VP2 secret immunoglobulin A (sIgA) antibody was detected by indirect ELISA in the feces, anti-PPV VP2 and anti-CSFV E290 peptide immunoglobulin G (IgG) antibody was detected by indirect ELISA in the serum of immunized mice after intragastric administration. The results indicated that the mice immunized with recombinant strain pPG-VP2-E290/L. casei 393 could produce clear antibody level, which establish important material basement for the development of lactic acid bacteria oral vaccine of recombinant CSFV and PPV.