title: Effectiveness of F18+Fimbrial Antigens Released by a Novel AutolyzedSalmonellaExpression System as a Vaccine Candidate against Lethal F18+STEC Infection.
abstract: Porcine edema disease (ED) caused by Shiga toxin 2e producingEscherichia coliexpressing F18ab+fimbriae (F18ab+STEC) frequently occurs in post-weaned piglets, resulting in a significant economic loss in swine industries worldwide. In the present study, we proposed an efficient prevention scheme against ED in which the attenuatedSalmonellaTyphimurium inactivated by theE-mediated cell lysis to deliver target antigens, FedF and FedA, which function in fimbrial-mediated adhesion and as a major subunit of F18ab+fimbriae, respectively. The co-expression of FedA and FedF protein with outer membrane protein A signal peptide was confirmed in the resultant strains JOL1460 and JOL1464 by immunoblot analysis. Immunization with the candidate strains in mice led to the significant generation of immunoglobulin (Ig) G, specific to both antigens and secretory IgA specific to FedF (P< 0.05). The titers of IgG isotypes, IgG1 and IgG2a, used as markers for T-helpers (Th)-2 and Th-1lymphocytes, respectively, also significantly increased in the immunized group (P< 0.05). The increase in CD3+CD4+T lymphocyte subpopulation andin vitroproliferative activity was observed inin vivostimulated splenocytes, which indicated the immunostimulatory effect of the candidate strains. Moreover, the immunized mice were completely protected from a lethal challenge against wild-type F18+STEC whereas 28% of mice died in the non-immunized group. This study demonstrated that the inactivatedSalmonellasystem could efficiently release FedF and FedA and induce robust immune responses specific to the target antigens, which is sufficient to protect the mice from the lethal challenge.
authors.affiliation: College of Veterinary Medicine, Chonbuk National University Iksan, South Korea.
authors.forename: Gayeon
authors.initials: G
authors.lastname: Won
authors.affiliation: College of Veterinary Medicine, Chonbuk National University Iksan, South Korea.
authors.forename: John H
authors.initials: JH
authors.lastname: Lee
keywords: F18 fimbriae; STEC; inactivated Salmonella delivery system; porcine edema disease