Nanostructure-based platform for CpG-ODN promotes enhanced CD8+ T cell effector response to protein antigen and accelerates seroconversion

ANA LAURA CHIODETTI; MARÍA FERNANDA SÁNCHEZ VALLECILLO; MARÍA INÉS CRESPO; GABRIEL MORÓN; SANTIAGO PALMA; MARÍA CRISTINA PISTORESI; DANIEL ALLEMANDI; BELKYS ANGELICA MALETTO

Mar del Plata

Congreso; LXII Reunión Científica de la Sociedad Argentina de Inmunología; 2014

SAI

Previously, we have shown that immunostimulatory CpG-ODN formulated in a nanostructure of 6-O-ascorbyl palmitate (Coa-ASC16) has the capacity of enhancing a specific immune response in a more efficient manner than the CpG-ODN solution alone using OVA as an antigen model. In order to further evaluate the advantage of this formulation in the specific immune response, we analyses the kinetic of antibody response and the capacity to generate cytotoxic CD8+ T lymphocyte (CTL) response. Mice were s.c. immunized on day 0 with OVA/CpG-ODN/Coa-ASC16 formulation or OVA/CpG-ODN solution (dose/mice: OVA: 60μg, CpG-ODN: 75 μg) and plasma was obtained on days 8, 10, 13, 16, 19, 22, 35, 49 and 65 post immunization for OVA-specific IgG titers analysed by ELISA. On day 8, plasma from both groups was not reactive. At day 10 only OVA/CpG-ODN/Coa-ASC16 immunized mice elicited IgG response (2.1±0.2 vs not detected). After day 10 the OVA/CpG-ODN/Coa-ASC16 group presented higher IgG titles than OVA/CpG-ODN group (p<0.001). For CTL determination, an in vivo killing assay was performed. Mice were s.c. immunized on day 0, 7 and 14 with OVA/CpG-ODN/Coa-ASC16 or OVA/CpG-ODN (dose/mice: OVA: 60μg, CpG-ODN: 75μg). Mice immunized with OVA/CpG-ODN/Coa-ASC16 presented on day 21 a more effective specific lysis percentage than mice immunized with OVA/CpG-ODN (79±6 % vs 16±6 %, p<0.02). At the same time, IFN-γ was assayed by ELISA in supernatants of splenocytes from this immunized mice after reestimulation in vitro with 0.1 μg/ml of OVA257-264 during 72 h; the splenocytes from OVA/CpG-ODN/Coa-ASC16 mice secreted higher levels of IFN-γ than those from OVA/CpG-ODN mice (p<0.05). Our results show that this nanostructure-based vaccine platform accelerates specific antibody seroconversion and improves the efficiency of antigen-specific cytotoxic CD8+ T cell response demonstrating the potentiality of this strategy as a new adjuvant option for future vaccines.