Activated Charcoal Enhanced the Antigen-expression and Dendritic Cell Maturation of the Vaccine Using Listeria-platform

Background: Listeria monocytogenes (LM) has been used as a vaccine vector based upon its ability to induce a strong cell-mediated immune response. LM inactivated with -irradiation retains immunogenic properties and is an attractive platform for clinical use since it would have improved safety concerns compared to live vectors. Activated charcoal has been shown to enhance expression of LM proteins such as PrfA. Aim: To investigate the effect of various growth conditions supplemented with activated charcoal on recombinant antigen expression. Methods: We prepared -irradiated ovalbumin-expressing LM ( LM-OVA) after growth under various culture conditions. We cultured LM-OVA at various temperatures including 25C, 37C and 37C with activated charcoal and compared OVA expression by western blot analysis, dendritic cells maturation and OVA-specific T cells. Results: The OVA expression was highest in -irradiated LM-OVA grown with activated charcoal at 37C. Compared to other growth conditions, -irradiated LM-OVA grown with activated charcoal at 37C induce better DC maturation as well as production of the highest number of antigen-specific IFN-secreting T cells. Conclusion: The further study should be demonstrated the potential to alter growth conditions to enhance OVA expression resulting for vaccine vectors, thereby improving their safety and efficacy.