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

FEDERICO, RUIZ MORENO; CONSTANZA, MARIN; NICOLAS, DHO; MARIA MERCEDES, PASCUAL; DANIEL A., ALLEMANDI; SANTIAGO D., PALMA; MARIA C, PISTORESI-PALENCIA; VICTOR G., MORÓN; BELKYS A., MALETTO

Congreso; REUNIÓN DE SOCIEDADES DE BIOCIENCIAS 2020. LXV REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC). LXVIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI). REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE FISIOLOGÍA (SAFIS); 2020

SOCIEDADES DE BIOCIENCIAS

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.