Clin Exp Vaccine Res.  2016 Jul;5(2):148-158. 10.7774/cevr.2016.5.2.148.

Protective efficacy and immune responses by homologous prime-booster immunizations of a novel inactivated Salmonella Gallinarum vaccine candidate

• Won G
• Chaudhari
• Lee JH

• KMID: 2421562
• DOI: http://doi.org/10.7774/cevr.2016.5.2.148

Abstract

PURPOSE
Salmonella enterica serovar Gallinarum (SG) ghost vaccine candidate was recently constructed. In this study, we evaluated various prime-boost vaccination strategies using the candidate strain to optimize immunity and protection efficacy against fowl typhoid.
MATERIALS AND METHODS
The chickens were divided into five groups designated as group A (non-immunized control), group B (orally primed and boosted), group C (primed orally and boosted intramuscularly), group D (primed and boosted intramuscularly), and group E (primed intramuscularly and boosted orally). The chickens were primed with the SG ghost at 7 days of age and were subsequently boosted at the fifth week of age. Post-immunization, the plasma IgG and intestinal secretory IgA (sIgA) levels, and the SG antigen-specific lymphocyte stimulation were monitored at weekly interval and the birds were subsequently challenged with a virulent SG strain at the third week post-second immunization.
RESULTS
Chickens in group D showed an optimized protection with significantly increased plasma IgG, sIgA, and lymphocyte stimulation response compared to all groups. The presence of CD4+ and CD8+ T cells and monocyte/macrophage (M/M) in the spleen, and splenic expression of cytokines such as interferon γ (IFN-γ) and interleukin 6 (IL-6) in the immunized chickens were investigated. The prime immunization induced significantly higher splenic M/M population and mRNA levels of IFN-γ whereas the booster showed increases of splenic CD4+ and CD8+ T-cell population and IL-6 cytokine in mRNA levels.
CONCLUSION
Our results indicate that the prime immunization with the SG ghost vaccine induced Th1 type immune response and the booster elicited both Th1- and Th2-related immune responses.

Keyword

Salmonella; Ghost vaccine; Immunization scheme; Protection; Fowl typhoid

MeSH Terms

Birds
Chickens
Cytokines
Immunization*
Immunoglobulin A, Secretory
Immunoglobulin G
Interferons
Interleukin-6
Lymphocyte Activation
Plasma
RNA, Messenger
Salmonella enterica
Salmonella*
Serogroup
Spleen
T-Lymphocytes
Typhoid Fever
Vaccination
Cytokines
Immunoglobulin A, Secretory
Immunoglobulin G
Interferons
Interleukin-6
RNA, Messenger