Immune response induced by new adjuvant strategy to produce crotalic antivenom

LUCIANO FUSCO , MARÍA MERCEDES PASCUAL, MARIA FERNANDA SANCHEZ VALLECILLO, ARRIETA MARIA BELEN , DAVID HERNÁNDEZ , SANTIAGO PALMA , BELKYS ANGELICA MALETTO, GABRIEL MORON, LAURA CRISTINA LEIVA

Mar del Plata

Congreso; Reunión Conjunta - Sociedad Argentina de Investigación Clínica (SAIC) - Sociedad Argentina de Inmunología (SAI) - Sociedad Argentina de Fisiología (SAFIS); 2018

SAI

Snake envenomation is a serious medical problem in tropical developing countries and antivenoms are the main treatment. Antisera are produced by immunization of horses with snake venom using complete Freund?s adjuvant and incomplete (booster) but it causes severe local reactions. A new adjuvant strategy is required to increase efficiency in antisera production under much less morbilty to immunized animals. CpG-ODN formulated in a 6-O-ascorbyl palmitate nanostructure (Coa-ASC16) was more efficient as adjuvant than CpG-ODN alone using ovalbumin (OVA) as an antigen model. Particularly, immunization of mice with OVA/CpG-ODN/Coa-ASC16 resulted in high OVA-specific antibody titers and IFN-γ and IL-17 secretion compared to immunization with OVA/CpG-ODN. In order to evaluate the immune response induced by this adjuvant strategy using Crotalus durissus terrificus (C.d.t) venom, we determined the titer of antibodies (IgG, IgG1 and IgG2) and their specificity. Balb/c mice were subcutaneously immunizated on days 0, 15 and 30 with C.d.t venom/CpG-ODN/Coa-ASC16 or C.d.t venom/Freund?s Adyuvant (complete first and incomplete-booster) (dose/mice: C.d.t venom: 10-15μg, CpG-ODN: 30 μg). On day 50 mice were sacrificed. In both immunized group mice, the antibody titers in plasma were high (1x105), with a similar IgG1/IgG2a ratio. The antibodies recognized phospholipase A2 and thrombine like protein but not all C.d.t venom components. Macroscopic and microscopic analysis at the site of injection of mice injected with Freund?s adjuvant showed local damage (with non-infectious abscesses) and hypertrophy of inguinal lymph nodes, whereas mice injected with CpG-ODN/Coa-ASC16 did not. Our results show that CpG-ODN/Coa-ASC16 produces a humoral response as strong and specific as Freund´sadjuvant, with minor or null local deleterious effect, demonstrating the potentiality and advisability of this complex as a new adjuvant option for future immunizations to produce C.d.t antivenom.