Corrigendum to “CpG-ODN formulated with a nanostructure as adjuvant for anticrotalic serum production. Studies in mice” [Toxicon 215 (2022) 28–36]

Abstract

Antivenom is the only safe and effective treatment to neutralize snake venom. Specific anti-venom used to treat snake bite is usually obtained from horses after

hyperimmunization with crude snake venom in combination with Freund’s Adjuvant. Freund’s complete and incomplete adjuvant can cause severe local and sys- temic acute and chronic inflammation, its potentially severe inflammatory effects have led many researchers to seek alternative immunological adjuvants. 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 im- munization with OVA/CpG-ODN. First of all, we estimated the effect of Coa-ASC16 nanostructure preparation on venom activity. Additionally, in order to evaluate

the immune response induced by this adjuvant strategy using Crotalus durissus terrificus (C. d. terrificus) venom (CdtV), 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 CdtV/CpG-ODN/Coa-ASC16 or CdtV/Freund’s Adyuvant (complete first and incomplete-booster) (dose/mice: CdtV: 6–10 μg, CpG-ODN: 30 μg). On day 45 mice were sacrificed. The neutralizing ability of serum from animals immunized with CdtV/CpG-ODN/Coa-ASC16 or CdtV/Freund’s adjuvant was tested against PLA2 activity and lethality. In both immunized group mice, the antibody titers in plasma were high (1 × 105

), with a similar IgG1/IgG2a ratio. The antibodies recognized phospholipase A2 and thrombin-like proteins, the main toxins from C. d. terrificus venom. 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’s adjuvant, with minor or null local deleterious effect, demonstrating the potentiality and

advisability of an alternative formulation as a new adjuvant option for future immunizations to produce C. d. terrificus antivenom.