A NANOSTRUCTURE OF ASCORBYL PALMITATE USED AS VACCINE PLATFORM IMPROVE ANTIGEN-SPECIFIC MEMORY RESPONSE AND RETAINS THE ANTIGEN AT THE INJECTION SITE

RUIZ MORENO, FEDERICO; MARÍN, CONSTANZA; DHO, NICOLÁS DANIEL; PASCUAL, MARÍA MERCEDES; ALLEMANDI, DANIEL A; PALMA, SANTIAGO D; PISTORESI, MARÍA CRISTINA; MORÓN, GABRIEL; MALETTO, BELKYS A

Congreso; Reunión Anual de Sociedades de Biociencias; 2020

SAI SAIC SAFIS

Previously, we demonstrated that the nanoformulation of OVA and CpG-ODN with a nanostructure formed by self-assembly of 6-O-ascorbyl palmitate (Coa-ASC16) elicited immune response superior to those induced by the soluble counterpart. Here, we studied the effects of various formulations of vaccine components on antigen-specific memory response and on antigen persistence at injection site. Mice were subcutaneously immunized with a single-dose of OVA and CpG-ODN nanoformulated with Coa-ASC16 (OCC), with OVA and CpG-ODN in solution (OC) prepared to room temperature (RT), with OVA and CpG-ODN solution heated and then cooled down to RT (OCø), with OVA solution heated and then cooled down to RT plus CpG-ODN solution at RT (Oø/C), with OVA solution at RT plus CpG-ODN solution heated and then cooled down to RT (O/Cø). Heating and cooling processes recreated the conditions of the nanoformulation preparation. On the 160th day of post-immunization (pi), mice were intraperitoneally challenged with OVA/CpG-ODN and sacrificed 7 days later. OVA-anti IgG titers (ELISA) and splenocytes by flow cytometry were evaluated. When antigens at the injection site were measured, the formulations were prepared using fluorescent-dye labeled OVA and in vivo scanning of mice was performed on Odyssey®CLx. OCC induced IgG titers higher than OCø and Oø/C at 145 day pi (p<0.001). Post challenged (day 167), OCC IgG titers were comparable to OCø group and higher to Oø/C group (p<0.01). O/Cø failed to generate OVA-specific IgG. At 167 days pi, OCC generated higher OVA-specific (CD3-F480- CD19+ IgM- IgD- IgG+ GL7- CD38+ OVA+) memory and germinal center (CD3- F480- CD19+ IgM- IgD- IgG+ GL7+ CD38- OVA+) B cells (p<0.05) than the other formulations. In OCC group, the OVA fluorescence signal in the injection site was higher than in the other groups since 0.3 (p<0.0001) until 12 days pi (p<0.01). Our results show that the nanostructure improve the memory response and induce antigen depot at the injection site