title: Characterization of a novel inactivated Salmonella enterica serovar Enteritidis vaccine candidate generated using a modified cI857/λ PR/gene E expression system.
abstract: A new strategy to develop an effective vaccine is essential to control food-borne Salmonella enterica serovar Enteritidis infections. Bacterial ghosts (BGs), which are nonliving, Gram-negative bacterial cell envelopes, are generated by expulsion of the cytoplasmic contents from bacterial cells through controlled expression using the modified cI857/λ P(R)/gene E expression system. In the present study, the pJHL99 lysis plasmid carrying the mutated lambda pR37-cI857 repressor and PhiX174 lysis gene E was constructed and transformed in S. Enteritidis to produce a BG. Temperature induction of the lysis gene cassette at 42°C revealed quantitative killing of S. Enteritidis. The S. Enteritidis ghost was characterized using scanning and transmission electron microscopy to visualize the transmembrane tunnel structure and loss of cytoplasmic materials, respectively. The efficacy of the BG as a vaccine candidate was evaluated in a chicken model using 60 10-day-old chickens, which were divided into four groups (n = 15), A, B, C, and D. Group A was designated as the nonimmunized control group, whereas the birds in groups B, C, and D were immunized via the intramuscular, subcutaneous, and oral routes, respectively. The chickens from all immunized groups showed significant increases in plasma IgG and intestinal secretory IgA levels. The lymphocyte proliferation response and CD3(+) CD4(+) and CD3(+) CD8(+) T cell subpopulations were also significantly increased in all immunized groups. The data indicate that both humoral and cell-mediated immune responses are robustly stimulated. Based on an examination of the protection efficacy measured by observations of gross lesions in the organs and bacterial recovery, the candidate vaccine can provide efficient protection against virulent challenge.
authors.affiliation: College of Veterinary Medicine, Chonbuk National University, Jeonju, Republic of Korea.
authors.forename: Chetan V
authors.initials: CV
authors.lastname: Jawale
authors.forename: Atul A
authors.initials: AA
authors.lastname: Chaudhari
authors.forename: Byung Woo
authors.initials: BW
authors.lastname: Jeon
authors.forename: Rahul M
authors.initials: RM
authors.lastname: Nandre
authors.forename: John Hwa
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002462:Cell Membrane / Q000276:immunology*; D002645:Chickens / Q000276:immunology / Q000382:microbiology; D004333:Drug Administration Routes / Q000662:veterinary; D005814:Genes, Viral; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008213:Lymphocyte Activation; D010957:Plasmids; D011201:Poultry Diseases / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D012481:Salmonella Infections, Animal / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D022562:Salmonella Vaccines / Q000276:immunology*; D012477:Salmonella enteritidis / Q000276:immunology*; D015164:Vaccines, Inactivated / Q000276:immunology; D014764:Viral Proteins / Q000235:genetics
chemical_list: D000907:Antibodies, Bacterial; C029555:E protein, bacteriophage X174; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D022562:Salmonella Vaccines; D015164:Vaccines, Inactivated; D014764:Viral Proteins