Oral immunization with an attenuated Salmonella Gallinarum mutant as a fowl typhoid vaccine with a live adjuvant strain secreting the B subunit of Escherichia coliheat-labile enterotoxin

Abstract

BackgroundThe Salmonella Gallinarum (SG) lon/cpxR deletion mutant JOL916 was developed as a live vaccine candidate for fowl typhoid (FT), and a SG mutant secreting an Escherichia coli heat-labile enterotoxin B subunit (LTB), designated JOL1229, was recently constructed as an adjuvant strain for oral vaccination against FT. In this study, we evaluated the immunogenicity and protective properties of the SG mutant JOL916 and the LTB adjuvant strain JOL1229 in order to establish a prime and boost immunization strategy for each strain. In addition, we compared the increase in body weight, the immunogenicity, the egg production rates, and the bacteriological egg contamination of these strains with those of SG 9R, a widely used commercial vaccine.ResultsPlasma IgG, intestinal secretory IgA (sIgA), and cell-mediated responses were significantly induced after a boost inoculation with a mixture of JOL916 and JOL1229, and significant reductions in the mortality of chickens challenged with a wild-type SG strain were observed in the immunized groups. There were no significant differences in increases in body weight, cell-mediated immune responses, or systemic IgG responses between our vaccine mixture and the SG 9R vaccine groups. However, there was a significant elevation in intestinal sIgA in chickens immunized with our mixture at 3 weeks post-prime-immunization and at 3 weeks post-boost-immunization, while sIgA levels in SG 9R-immunized chickens were not significantly elevated compared to the control. In addition, the SG strain was not detected in the eggs of chickens immunized with our mixture.ConclusionOur results suggest that immunization with the LTB-adjuvant strain JOL1229 can significantly increase the immune response, and provide efficient protection against FT with no side effects on body weight, egg production, or egg contamination.

Recombinant-attenuated Salmonella Pullorum strain expressing the hemagglutinin-neuraminidase protein of Newcastle disease virus (NDV) protects chickens against NDV and Salmonella Pullorum challenge

“…Cell-mediated immune responses can be represented by the SI of lymphocytes by using a specific antigen [ 2 19 ]. Significant cell-mediated immune responses were shown by the peripheral blood lymphocyte proliferation assay in both the C79-13Δ crp Δ asd (pYA-HN) and NDV live vaccine groups to be greater than that of the control group at 21 days after immunization ( p < 0.05) ( Fig.…”

“…Over the past 30 years, research into attenuated Salmonella as an oral live vaccine vector to carry and express exogenous protective antigen genes of pathogens has become popular. It has been reported that using attenuated Salmonella to construct recombinant live vaccines not only has the ability to activate the body's immune system to resist Salmonella infection, but it also can significantly enhance the immune effect of the exogenous gene being carried [ 18 19 27 30 35 ]. In this study, the survival rates of the chicken challenged chicken with the C79-13 strain after immunization with C79-13Δ crp Δ asd (pYA-HN) or C79-13Δ crp Δ asd (pYA) were 100% ( Table 1 ).…”

Comparative evaluation of safety and efficacy of a live Salmonella gallinarum vaccine candidate secreting an adjuvant protein with SG9R in chickens

“…In our previous studies, we used live attenuated SG secreting LTB (JOL1229) as an adjuvant for JOL916 (Jeon et al, 2012(Jeon et al, , 2013. However, such adjuvant-vaccine compositions may be inconvenient to implement in the poultry industry due to uneconomical formulations.…”

<i>Salmonella </i>Serovars and Vaccination Effect on the Immune Responses of Male and Female Layers

“…Additionally, an oral vaccination with S. Gallinarum increases plasma IgG, intestinal secretory IgA and cell-mediated responses (Jeon et al, 2013). In study of immune responses, S. Enteritidis, S. Gallinarum and S. Pullorum stimulated expressions differently of cytokine and chemokine gene of cecal tonsil in newly hatched chicks and older chickens (Setta et al, 2012).…”