A live attenuated Salmonella Enteritidis secreting detoxified heat labile toxin enhances mucosal immunity and confers protection against wild-type challenge in chickens.
A live attenuated Salmonella Enteritidis (SE) capable of constitutively secreting detoxified double mutant Escherichia coli heat labile toxin (dmLT) was developed. The biologically adjuvanted strain was generated via transformation of a highly immunogenic SE JOL1087 with a plasmid encoding dmLT gene cassette; the resultant strain was designated JOL1641. A balanced-lethal host-vector system stably maintained the plasmid via auxotrophic host complementation with a plasmid encoded aspartate semialdehyde dehydrogenase (asd) gene. Characterization by western blot assay revealed the dmLT subunit proteins in culture supernatants of JOL1641. For the investigation of adjuvanticity and protective efficacy, chickens were immunized via oral or intramuscular routes with PBS, JOL1087 and JOL1641. Birds immunized with JOL1641 showed significant (P ≤ 0.05) increases in intestinal SIgA production at the 1(st) and 2(nd) weeks post-immunization via oral and intramuscular routes, respectively. Interestingly, while both strains showed significant splenic protection via intramuscular immunization, JOL1641 outperformed JOL1087 upon oral immunization. Oral immunization of birds with JOL1641 significantly reduced splenic bacterial counts. The reduction in bacterial counts may be correlated with an adjuvant effect of dmLT that increases SIgA secretion in the intestines of immunized birds. The inclusion of detoxified dmLT in the strain did not cause adverse reactions to birds, nor did it extend the period of bacterial fecal shedding. In conclusion, we report here that dmLT could be biologically incorporated in the secretion system of a live attenuated Salmonella-based vaccine, and that this construction is safe and could enhance mucosal immunity, and protect immunized birds against wild-type challenge.
Department of Bioactive Material Sciences and Department of Veterinary Public Health, College of Veterinary Medicine, Chonbuk National University, Iksan Campus, Iksan, 570-752, Republic of Korea.
Jonathan
J
Lalsiamthara
Department of Bioactive Material Sciences and Department of Veterinary Public Health, College of Veterinary Medicine, Chonbuk National University, Iksan Campus, Iksan, 570-752, Republic of Korea.
Nitin Machindra
NM
Kamble
Department of Bioactive Material Sciences and Department of Veterinary Public Health, College of Veterinary Medicine, Chonbuk National University, Iksan Campus, Iksan, 570-752, Republic of Korea. johnhlee@jbnu.ac.kr.
John Hwa
JH
Lee
D000818:Animals; D001427:Bacterial Toxins / Q000276:immunology*; D002645:Chickens / Q000276:immunology / Q000382:microbiology; D004768:Enterotoxins / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000276:immunology*; D018928:Immunity, Mucosal / Q000276:immunology*; D008297:Male; 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 / Q000627:therapeutic use*; D012477:Salmonella enteritidis / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000276:immunology / Q000627:therapeutic use
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022562:Salmonella Vaccines; D014613:Vaccines, Attenuated; C027538:heat-labile enterotoxin, E coli