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

FEDERICO DANIEL RUIZ MORENO; CONSTANZA MARIN; NICOLAS DANIEL DHO; MERCEDES PASCUAL; DANIEL ALLEMANDI; SANTIAGO PALMA; MARÍA C PISTORESI- PALENCIA; G MORON; BELKYS A. MALETTO

Buenos Aires

Congreso; LXVIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2020

SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI)

Previously, we demonstrated that the nanoformulation of OVAand CpG-ODN with a nanostructure formed by self-assembly of6-O-ascorbyl palmitate (Coa-ASC16) elicited immune responsesuperior to those induced by the soluble counterpart. Here, westudied the effects of various formulations of vaccine componentson antigen-specific memory response and on antigen persistenceat 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 roomtemperature (RT), with OVA and CpG-ODN solution heated and thencooled down to RT (OCø), with OVA solution heated and then cooleddown to RT plus CpG-ODN solution at RT (Oø/C), with OVA solutionat RT plus CpG-ODN solution heated and then cooled down to RT(O/Cø). Heating and cooling processes recreated the conditions ofthe nanoformulation preparation. On the 160th day of post-immunization(pi), mice were intraperitoneally challenged with OVA/CpGODNand sacrificed 7 days later. OVA-anti IgG titers (ELISA) andsplenocytes by flow cytometry were evaluated. When antigens atthe injection site were measured, the formulations were preparedusing fluorescent-dye labeled OVA and in vivo scanning of micewas performed on Odyssey®CLx. OCC induced IgG titers higherthan OCø and Oø/C at 145 day pi (p<0.001). Post challenged (day167), OCC IgG titers were comparable to OCø group and higher toOø/C group (p<0.01). O/Cø failed to generate OVA-specific IgG. At167 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) thanthe other formulations. In OCC group, the OVA fluorescence signalin 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 nanostructureimprove the memory response and induce antigen depotat the injection site.