Author ORCID Identifier

https://orcid.org/0000-0002-7031-2312

Date of Award

22-10-2024

Document Type

Thesis

School

School of Chemical & Biotechnology

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.Senthil Visaga Ambi

Second Advisor

Dr.T.Diraviyam

Keywords

Venom Toxins, Igy, Indian Big Four, Neutralization

Abstract

Envenomation resulting from snakebites is widely recognized as an alarming health risk in tropical and sub-tropical areas. The big four snakes including Naja naja, Bungarus caeruleus, Daboia russelli, Echis carinatus are responsible for most of the envenomation in India. The current therapy for snake envenomation is immunoglobulins, produced from serum or plasma of horses or sheep. To overcome the drawbacks of current antivenom, chicken egg yolk (IgY) antibodies have recently emerged as one of the most promising research avenues.

In this study, the efficacy of chicken egg yolk sourced antisnake venom (ASV) IgY against the big four venoms was evaluated by in-vivo and in-vitro experiments. Lethal dose determination studies in mice and chickens reveal that krait venom is more potent. The sub-lethal doses of venoms were immunized to the chickens and the titre was 1:64000 against all the venoms. On testing the scalability of IgY, water dilution method followed by tangential flow filtration and further purified by Ion-exchange chromatography would be suitable for large scale production of IgY.

IgY was found efficient in neutralizing the hemotoxic and pro-coagulant activities of venoms. Interestingly, IgY was able to inhibit the myotoxicity and nitric oxide production (inflammatory marker) in a dose-dependent manner. Further, study on the neutralization potency of IgY in mice had shown antivenom IgY raised against Bungarus caeruleus (0.028mg of venom/mL of ASV IgY) and Naja naja (0.22mg of venom/mL of ASV IgY) was very much congruent with the commercial antivenom IgG (Bungarus caeruleus - 0.035 mg/mL of ASV IgG; Naja naja - 0.28mg/mL of ASV IgG), while potency of IgY against Echis carinatus

(0.442mg of venom/mL of ASV IgY) was better than the commercial antivenom IgG (Echis carinatus - 0.095 mg of venom/mL of ASV IgG). Anti-Echis carinatus IgY was highly effective in neutralizing 2xLD50 dose of venom. However, the neutralization potency of IgY was less against Daboia russelii venom compared to other venoms. IgY exhibits pronounced inhibition against the edema-forming and haemorrhage activities induced by the venoms demonstrated in mice models.

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Graphical Abstract