NANOVACCINE PLATFORM CONTAINING TLR9 AGONIST IMPROVES GERMINAL CENTER RESPONSE.

FEDERICO, RUIZ MORENO; CONSTANZA, MARIN; ESPERANZA, FELICI; DANIEL A., ALLEMANDI; SANTIAGO D., PALMA; MARIA C, PISTORESI-PALENCIA; GABRIEL, MORÓN; BELKYS A. MALETTO

Congreso; eunión Anual de la Sociedad Argentina de Inmunología; 2021

We have previously reported that the nanoformulation of OVA and CpG-ODN with a nanostructure (Coa-ASC16) formed by self-assembly of 6-O-ascorbyl palmitate (ASC16) elicited an OVA-specific antibody response sustained for over 160 days and cellular immune response superior in magnitude and quality to those induced by vaccine components in solution. Here, we study the effect of various vaccine components formulations in the antigen-specific CD8+ T cells, germinal center B cells, and Tfh cells. We also evaluated the effect of ASC16 sterilization (gamma irradiation) on the immune response. Mice were subcutaneously immunized with a single dose of OVA and CpG-ODN nanoformulated with Coa-ASC16 (OCC), an OVA and CpG-ODN solution heated and then cooled down to RT (OCø), an OVA solution heated and then cooled down to RT plus a CpG-ODN solution at RT (øO/C), or with an OVA solution at RT plus a CpG-ODN solution heated and then cooled down to RT (O/øC). Heating and cooling processes recreated the conditions of the nanoformulation preparation. ELISA and flow cytometry techniques were used. In the group of mice immunized with OCC we found a response higher than the response elicited in the other groups of antigen-specific CD8+ T cells (CD3+ CD8+ SIINFEKL-Kb tetramer+) in blood 7-days post-immunization (p<0.0001), of Tfh cells (B220- CD3+ CD4+ CXCR5+) in the lymph node 10-days post-immunization (p<0.05), and of OVA-specific germinal center B cells (CD3- F480- CD19+ IgM- IgD- IgG+ GL7+ CD38- OVA+) in the lymph node 14-days post-immunization (6-days post-intraperitoneal challenge with OVA/CpG-ODN) (p<0.05). No changes were observed in the OVA-specific immune humoral and cellular response elicited by sterile ASC16 vs non-sterile ASC16. These data showed that the nanoformulation of vaccine components enhanced the germinal center response, which led to robust antibody responses. In addition, it was shown that the ASC-16 sterilization process does not affect performance.