Physiology, pathogenicity and immunogenicity oflonand/orcpxRdeleted mutants ofSalmonellaGallinarum as vaccine candidates for fowl typhoid

Abstract

To construct a novel live vaccine candidate for fowl typhoid (FT) caused by Salmonella Gallinarum (SG), the lon and cpxR genes that are related to host-pathogen interaction were deleted from a wild type SG using the allelic exchange method. The mutants were grown normally, as was the wild type. The biochemical properties of the mutants remained very similar to those of the wild-type, while JOL914 (Δlon) and JOL916 (ΔlonΔcpxR) were mucoid. Extracellular polysaccharide increased 30.6-, 1.3-, and 46.2-fold in JOL914, JOL915 (ΔcpxR), and JOL916, respectively. Dot-blot analysis demonstrated significant increases of FimA expression at 6.77-, 2.33-, and 3.90-fold for JOL914, JOL915, and JOL916, respectively. Internalizations of JOL914, JOL915, and JOL916, in chicken abdominal macrophages, were increased at 4.65-, 0.50-, and 2.72-fold, respectively. Virulences of JOL914, JOL915 and JOL916, analyzed by LD50 using 1-week-old chickens, were attenuated approximately at 101-, 101-, and > 103-fold, respectively. The oral inoculations of 2 × 107 cfu of the wild type, JOL914, JOL915 and JOL916 caused 55.6, 16.7, 22.2, and 0.0% mortality, respectively. Significantly moderate gross lesions of the liver and spleen were observed in the JOL916 group compared to the other groups. An induced immune response and significant peripheral mononuclear proliferation reaction were observed in the JOL916 group. At the protection against the wild type challenge, JOL916 offered 100% protection. Thus, the results of this study suggest that JOL916 among the mutants studied represented the safest and most effective live vaccine candidate against FT.

Downregulation of Chicken Interleukin-17 Receptor A during Eimeria Infection

“…This pathogen enters the small intestine and is carried to various organs, including the spleen and liver (46)(47)(48). Expression of chicken IL-17 transcript increases in the cecum during Salmonella enterica serovar Enteritidis infection (20,49).…”

Salmonella enterica Serovar Enteritidis Ghosts Carrying the Escherichia coli Heat-Labile Enterotoxin B Subunit Are Capable of Inducing Enhanced Protective Immune Responses

“…Titers of S. Enteritidis antigen-specific immunoglobulin G (IgG) and secretory immunoglobulin A (sIgA) antibodies, in addition to LTB-specific IgG titers, were determined by indirect ELISA following immunization. Plasma samples were obtained by centrifuging heparinized blood samples collected from the wing vein, whereas intestinal wash samples were collected using the pilocarpine-based intestinal lavage procedure, as previously described (20). To quantify S. Enteritidis-specific plasma IgG and intestinal sIgA titers, outer membrane protein (OMP) (extracted from S. Enteritidis strain JOL860 cells) was used as the coating antigen.…”

Pathogenic traits of Salmonella Montevideo in experimental infections in vivo and in vitro

“…Macrophage uptake of SM and reference strains was assessed as described earlier40 with minor modifications. The experiment was performed by infecting chicken primary intraperitoneal macrophages with a multiplicity of infection (MOI) of 10:1.…”