CpG-ODN formulated with a nanostructure as adjuvant for anticrotalic serum production. Studies in mice

LUCIANO S. FUSCO; MARÍA M. PASCUAL; DAVID HERNANDEZ; MARÍA FERNANDA S. VALLECITO; MARÍA B. ARRIETA; MORON, GABRIEL; SANTIAGO PALMA; BELKYS MALETO; LAURA C. LEIVA

TOXICON

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2022 vol. 215 p. 28 - 36

0041-0101

Antivenom is the only safe and effective treatment to neutralize snake venom. Specificanti-venom used to treat snake bite is usually obtained from horses afterhyperimmunization with crude snake venom in combination with Freund’s Adjuvant.Freund´s complete and incomplete adjuvant can cause severe local and systemicacute and chronic inflammation, its potentially severe inflammatory effects have ledmany researchers to seek alternative immunological adjuvants. CpG-ODN formulatedin a 6-O-ascorbyl palmitate nanostructure (Coa-ASC16) was more efficient as adjuvantthan CpG ODN alone using ovalbumin (OVA) as an antigen model. Particularly,immunization of mice with OVA/CpG-ODN/Coa-ASC16 resulted in high OVA specificantibody titers and IFN-γ and IL-17 secretion compared to immunization withOVA/CpG-ODN. First of all, we estimated the effect of Coa-ASC16 nanostructurepreparation on venom activity. Additionally, in order to evaluate the immune responseinduced by this adjuvant strategy using Crotalus durissus terrificus ( C.d.terrificus)venom (CdtV), we determined the titer of antibodies (IgG, IgG1 and IgG2) and theirspecificity. Balb/c mice were subcutaneously immunizated on days 0, 15 and 30 withCdtV /CpG-ODN/Coa-ASC16 or CdtV /Freund’s Adyuvant (complete first andincomplete-booster) (dose/mice: CdtV: 10-15μg, CpG-ODN: 30 μg). On day 50 micewere sacrificed. In both immunized group mice, the antibody titers in plasma were high(1x10 5 ), with a similar IgG1/IgG2a ratio. The antibodies recognized phospholipase A2 and thrombine like protein a key toxins from C.d. terrificus venom components.Macroscopic and microscopic analysis at the site of injection of mice injected withFreund’s adjuvant showed local damage (with non-infectious abscesses) andhypertrophy of inguinal lymph nodes, whereas mice injected with CpG-ODN/CoaASC16 did not. Our preliminary results show that CpG ODN/Coa-ASC16 produces ahumoral response as strong and specific as Freund´s adjuvant, with minor or null localdeleterious effect, demonstrating the potentiality and advisability of this complex as anew adjuvant option for future immunizations to produce C.d.terrificus antivenom.