The development of IgY(ΔFc) antibody based neuro toxin antivenoms and the study on their neutralization efficacies

Abstract

Introduction. Immunotherapy for treatment of snake bites has been based on mammalian IgG. Recently, polyvalent ovine Fab has become available. However, papain, used in the Fab fragmentation process, is a human allergen. Avian eggs are a source of antibodies and a truncated version of IgY, IgY(ΔFc), is found in ducks. In this study, we induced duck antibodies by using detoxified cobra and krait venoms and then purified IgY(ΔFc) antibodies from the hyperimmune duck egg yolk. Methods. Ducks were used for immunization and their eggs were collected for antibody production. ICR strain female mice were used in the in vivo neutralization test. Monovalent antivenoms to Formosan cobra venom and Formosan multi-banded krait venom were raised and purified from hyper-immune duck egg yolk individually. The LD₅₀ of venoms were determined by subcutaneous injection of different venom doses into the mice. The survival/death ratios were recorded after 24 hours. Results. The antibody purified from egg yolk showed high titer response to its immunogen (cobra or krait venom) by an ELISA. Overall, the antibodies from duck eggs efficiently protected mice from envenomations. Discussion. The antivenoms purified from the egg yolk of ducks immunized with cobra venom and krait venom neutralized the lethal effects of these venoms with good efficacy in a mouse model. The antivenoms were effective in neutralizing lethality in mice injected at 4×LD₅₀ of venoms. Conclusions. These results indicate that antibodies derived from ducks can serve as a new source for the generation of antivenoms.

Keywords: :

• Duck IgY(ΔFc)
• Antivenom
• Neutralization
• Fab'
• Neurotoxin

Acknowledgments

The author acknowledges Center for Disease Control of Taiwan for providing cobra (Naja atra) venom.