Characterization of a Novel Inactivated Salmonella enterica Serovar Enteritidis Vaccine Candidate Generated Using a Modified cI857/λ P_R/GeneEExpression System

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>A new strategy to develop an effective vaccine is essential to control food-borne<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Salmonella enterica</jats:named-content>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<jats:sub>R</jats:sub>/gene<jats:italic>E</jats:italic>expression system. In the present study, the pJHL99 lysis plasmid carrying the mutated lambda pR37-cI857 repressor and PhiX174 lysis gene<jats:italic>E</jats:italic>was constructed and transformed in<jats:italic>S</jats:italic>. Enteritidis to produce a BG. Temperature induction of the lysis gene cassette at 42°C revealed quantitative killing of<jats:italic>S</jats:italic>. Enteritidis. The<jats:italic>S</jats:italic>. 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 (<jats:italic>n</jats:italic>= 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<jats:sup>+</jats:sup>CD4<jats:sup>+</jats:sup>and CD3<jats:sup>+</jats:sup>CD8<jats:sup>+</jats:sup>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.</jats:p>

Characterization of aSalmonellaTyphimurium ghost carrying an adjuvant protein as a vaccine candidate for the protection of chickens against virulent challenge

“…As bacterial ghosts retain all of the surface immunogenic determinants of their living counterparts, they are capable of stimulating strong immune responses, and their vaccine potential has been demonstrated experimentally for the prevention of pathogenic Gram-negative bacterial infections of veterinary importance Marchart et al, 2003;Chaudhari et al, 2012;Jawale et al, 2012;Hu et al, 2013). Here, we used Salmonella Typhimurium ghosts carrying LTB for vaccination experiments in the chicken model.…”

“…Vaccination trials in the laboratory or food-producing animals have demonstrated the ability of bacterial ghost vaccines to stimulate strong induction of immune responses accompanied by significant protection against virulent challenge (Wang & Lu, 2009;Chaudhari et al, 2012;Jawale et al, 2012;Hu et al, 2013). In our experiments, we employed only a fixed time window for challenge and reisolation of the bacteria, and a high dose of virulent challenge strain was used.…”

“…Bacterial ghosts are generated by the controlled expression of the plasmid-encoded PhiX174 lysis gene E encoding the 91-amino-acid residue hydrophobic protein E. The induction of protein E-mediated lysis leads to the formation of transmembrane tunnel structures by fusing the inner and outer membranes of Gram-negative bacteria, which consequently leads to a loss of cytoplasmic contents (Witte et al, 1992). To date, several studies have demonstrated that bacterial ghosts generated from pathogenic bacteria are capable of protecting against fatal Gram-negative infections Jalava et al, 2002;Marchart et al, 2003;Chaudhari et al, 2012;Jawale et al, 2012;Hu et al, 2013). Since the natural conformation of outer membrane proteins present in bacteria, including fimbriae, lipopolysaccharide, and peptidoglycan structures, is not altered during the production of bacterial ghosts, these empty bacterial envelopes possess high immunogenicity (Jalava et al, 2002).…”

Preparation and Evaluation of Chemically Inactivated Salmonella Enteritidis Vaccine in Chickens

“…BGs from pathogenic bacteria were reported to be controlled and can protect against infectious diseases [13]. The mucosal immunizations with Escherichia coli ghosts were reported to induce protective immunity in an SPF chicken model [14]. Furthermore, the oral vaccination of Edwardsiella tarda ghosts induced higher protection against infection in mice [15].…”

Salmonellaghosts expressing enterotoxigenicEscherichia colik88ab, k88ac, k99, and fasa fimbrial antigens induce robust immune responses in a mouse model

“…The method of preparation of ghost cells makes them effective vaccine candidates; as chemical or physical inactivation is not required, the immunogenic determinants are not denatured . In this study, the ghostinduction plasmid, pJHLP99 carrying the phiX174 lysis gene E Jawale et al 2012) was used to produce Salmonella ghosts. In addition, the plasmid pMMP81 harbors the aspartate b-semialdehyde dehydrogenase (asd) gene (Hur & Lee 2011b) and the ompA signal sequence; the genes encoding the fimbrial antigens were cloned into plasmid pMMP81 for expression of the fimbrial antigens in the JOL1255 strain.…”