This study aimed to investigate whether bacterial ghosts (BGs), empty cell envelopes of a gram-negative bacterium, delivering envelope protein domain III (EDIII) of dengue virus (DENV) serotype 2 could induce protective immune responses against dengue infection. In this study, we constructed Salmonella Typhimurium BGs expressing and delivering EDIII (BG-EDIII) and evaluated these ghosts for their immunogenicity studies in C57BL/6 mice. Our results demonstrated that the mice vaccinated once orally with BG-EDIII followed by an intramuscular boosting with a recombinant EDIII protein elicited significantly higher humoral and cell-mediated immune responses compared to the BGs alone vaccinated group (p<0.001). Upon challenge with DENV2, significantly lower viral load and liver damage was observed in BG-EDIII vaccinated group than BGs alone control group (p<0.05). The outcomes of this study revealed the ability of BG- EDIII to stimulate immune response with no observable damage to the vital organs.

Abstract
INTRODUCTION
MATERIALS AND METHODS
    Ethics statement
    Animals, virus and cell lines
    Production of Salmonella typhimurium BGs expressingDENV2 EDIII domain
    Immunization and challenge studies in C57BL/6 mice
    Measurement of antibody titers, cross reactivity andavidity
    Antigen-specific T cell responses
    Statistical analyses
RESULTS
    Confirmation of EDIII protein expressed by BGs
    BG-EDIII vaccine induces efficient DENV2-specifichumoral and cell-mediated immune responses
    BG-EDIII vaccine inhibits DENV2 viremia l
DISCUSSION
CONCLUSION
ACKNOWLEDGEMENTS
DECLARATION OF INTEREST
REFERENCES

• Gayeon Won(College of Veterinary Medicine, Jeonbuk National University)
• Irshad Ahmed Hajam(College of Veterinary Medicine, Jeonbuk National University)
• Perumalraja Kirthika(College of Veterinary Medicine, Jeonbuk National University)
• Eunha Kim(College of Veterinary Medicine, Jeonbuk National University)
• John Hwa Lee(College of Veterinary Medicine, Jeonbuk National University) Corresponding Author