The Veterinary quarterly 2017 03 20() 1-27 doi 10.1080/01652176.2017.1308040
In the pathogenicity of porcine edema disease, which is caused by the Escherichia coli-producing F18 and Shiga toxin, F18(+) fimbrial adhesins and Shiga toxin 2e (Stx2e) play pivotal roles in the colonization and enterotoxicity of this pathogen.
To develop a vaccine candidate against edema disease by combining three selected antigens of F18(+) Shiga toxin-producing Escherichia coli (STEC).
Genetically engineered Salmonella Typhimurium (ST) ghosts that express Stx2eB, FedF, and FedA were individually inserted in a ghost plasmid cassette (pJHL184), and the resultant plasmids were transformed into a Δasd Δlon ΔcpxR ST (JOL912). The individual expression of Stx2eB, FedF, and FedA with the outer membrane protein A signal peptide in JOL912 was validated by using an immunoblotting assay.
Immunization of the ghosts in BALB/c mice led to a significant increase in antigen-specific secretory IgA and serum IgG. Significantly marked elevation of the CD3(+)CD4(+) T cell subpopulation and lymphocyte proliferating activity in the primed splenocytes were also observed. Furthermore, mRNA of IL-4 and IFN-γ were highly upregulated in splenic T cells that were re-stimulated in vitro with individual purified antigens. Subsequently, the immunized mice showed significant protection efficacy against a lethal dose 50 of a virulent strain, resulting in approximately 85% and 92% survival rates in mice with a single- and double-dose immunization, respectively compared to only 40% of the non-immunized controls.
A mixture of the ghosts expressing these three antigens is a potential vaccine candidate for protection against the porcine edema disease.