Clin Exp Vaccine Res.  2021 May;10(2):132-140. 10.7774/cevr.2021.10.2.132.

Outer membrane proteins of Salmonella typhimurium as an adjuvant in rabies vaccine

• Negm II
• Ragab YM
• Mohamed AF

• KMID: 2525800
• DOI: http://doi.org/10.7774/cevr.2021.10.2.132

Abstract

Purpose
The objective of the present study was to evaluate the immune-enhancing potential of Salmonella typhimurium outer membrane protein (OMP) and alum as adjuvants towards inactivated Vero cells rabies vaccine (FRV/K2).
Materials and Methods
Six groups of female Sprague Dawley albino rats (10/group) were used in the evaluation of immunogenicity and safety of vaccines and adjuvants. Total immunoglobulin G secreted interferon-gamma (IFN-γ), and the percentage of proliferated CD4+ and CD8+ T cells were measured. Biochemical analysis and histopathological examination were used to test safety profiles.
Results
OMP adjuvanted rabies vaccine (FRV/K2+OMP) (OMP combined locally prepared vaccine) induced significantly higher neutralizing antibodies on day 21 post-vaccination relative to free (FRV/K2) vaccine and alum adsorbed vaccine (FRV/K2+alum) (alum adsorbed locally prepared vaccine). (FRV/K2+OMP) induced a significantly higher level of IFN-γ on day 14 post-vaccination. CD8+ T cells were significantly higher post-vaccination with reference (RV), free (FRV/K2), and (FRV/K2+OMP) than (FRV/K2+alum). On the contrary, CD4+ T cells were significantly elevated post-vaccination with (FRV/K2+alum) at p<0.05. Biochemical analysis and histopathological examination revealed that OMP could be used safely as an adjuvant for the development of more effective rabies vaccines.
Conclusion
Outer membrane proteins adjuvanted rabies vaccines would be beneficial to induce rapid neutralizing antibodies and essential cytokines.

Keyword

Rabies; Outer membrane proteins; Adjuvant; Vaccine; Immune response